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Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska, Elif Pehlivanoglu-Mantas, and Xiaojun Luo Analysis and Fate of Emerging Pollutants during Water Treatment Journal of Analytical Methods in Chemistry

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Page 1: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Guest Editors Fei Qi Guang-Guo Ying Kaimin Shih Jolanta Kumirska Elif Pehlivanoglu-Mantas and Xiaojun Luo

Analysis and Fate of Emerging Pollutants during Water Treatment

Journal of Analytical Methods in Chemistry

Analysis and Fate of Emerging Pollutantsduring Water Treatment

Journal of Analytical Methods in Chemistry

Analysis and Fate of Emerging Pollutantsduring Water Treatment

Guest Editors Fei Qi Guang-Guo Ying Kaimin ShihJolanta Kumirska Elif Pehlivanoglu-Mantas and Xiaojun Luo

Copyright copy 2013 Hindawi Publishing Corporation All rights reserved

This is a special issue published in ldquoJournal of Analytical Methods in Chemistryrdquo All articles are open access articles distributed underthe Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium providedthe original work is properly cited

Editorial Board

M Abdel-Rehim SwedenH Y Aboul Enein EgyptSilvana Andreescu USAA N Anthemidis GreeceA N Araujo PortugalR W Arndt SwitzerlandAna Cristi B Dias BrazilPierangelo Bonini ItalyArthur C Brown USAAntony C Calokerinos GreeceRicardo J Cassella BrazilXin-Sheng Chai ChinaO Chailapakul ThailandXingguo Chen ChinaC Collombel FranceW T Corns UKMiguel de la Guardia SpainIvonne Delgadillo PortugalE Dellacassa UruguayCevdet Demir TurkeyM Bonner Denton USAGregory W Diachenko USAM E Diaz-Garcia SpainDieter M Drexler USAJianxiu Du ChinaJenny Emneus DenmarkG Eppe BelgiumJosep Esteve-Romero SpainO Fatibello-Filho BrazilPaul S Francis AustraliaJuan F Garcia-Reyes SpainC Georgiou GreeceKate Grudpan ThailandR Haeckel Germany

Arafa I Hamed EgyptKaroly Heberger HungaryBernd Hitzmann GermanyChih-Ching Huang TaiwanI Isildak TurkeyJaroon Jakmunee ThailandXiue Jiang ChinaSelhan Karagoz TurkeyHiroyuki Kataoka JapanSkip Kingston USAChristos Kontoyannis GreeceR Kowalski PolandAnnamalai S Kumar IndiaIlkeun Lee USAJoe Liscouski USAEulogio J Llorent-Martinez SpainMercedes G Lopez MexicoMiren Lopez de Alda SpainLarisa Lvova ItalyJos Carlos Marques PortugalChristophe A Marquette FranceJean Louis Marty FranceSomenath Mitra USASerban C Moldoveanu USAMaria B Montenegro PortugalG A Nagana Gowda USAMilka Neshkova BulgariaB Nikolova-Damyanova BulgariaSune Nygaard DenmarkC K OrdquoSullivan SpainGangfeng Ouyang ChinaSibel A Ozkan TurkeyVeronica Pino SpainKrystyna Pyrzynska Poland

Jose B Quintana SpainMohammad A Rashid BangladeshD P S Rathore IndiaPablo Richter ChileFabio R P Rocha BrazilErwin Rosenberg AustriaGiuseppe Ruberto ItalyAntonio R Medina SpainBradley B Schneider CanadaGuoyue Shi ChinaJesus S Gandara SpainHana Sklenarova Czech RepublicN H Snow USAP B Stockwell UKF O Suliman OmanIt-Koon Tan SingaporeD G Themelis GreeceNilgun Tokman TurkeyNelson Torto South AfricaMarek Trojanowicz PolandParis Tzanavaras GreeceBengi Uslu TurkeyKrishna K Verma IndiaAdam Voelkel PolandFang Wang USAHai-Long Wu ChinaHui-Fen Wu TaiwanQingli Wu USAMengxia Xie ChinaRongda Xu USAXiu-Ping Yan ChinaLu Yang CanadaC Yin China

Contents

Analysis and Fate of Emerging Pollutants during Water Treatment Fei Qi Guang-Guo Ying Kaimin ShihJolanta Kumirska Elif Pehlivanoglu-Mantas and Xiaojun LuoVolume 2013 Article ID 256956 1 page

Occurrence and Removal Characteristics of Phthalate Esters from Typical Water Sources in NortheastChina Yu Liu Zhonglin Chen and Jimin ShenVolume 2013 Article ID 419349 8 pages

Simultaneous Determination of Hormonal Residues in Treated Waters Using Ultrahigh PerformanceLiquid Chromatography-Tandem Mass Spectrometry Rayco Guedes-Alonso Zoraida Sosa-Ferreraand Jose Juan Santana-RodrıguezVolume 2013 Article ID 210653 8 pages

Removal Efficiency and Mechanism of Sulfamethoxazole in Aqueous Solution by Bioflocculant MFXJie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei WeiVolume 2013 Article ID 568614 8 pages

Pyrite Passivation by Triethylenetetramine An Electrochemical Study Yun Liu Zhi Dang Yin Xuand Tianyuan XuVolume 2013 Article ID 387124 8 pages

A Green Preconcentration Method for Determination of Cobalt and Lead in Fresh Surface and WasteWater Samples Prior to Flame Atomic Absorption Spectrometry Naeemullah Tasneem Gul KaziFaheem Shah Hassan Imran Afridi Sumaira Khan Sadaf Sadia Arian and Kapil Dev BrahmanVolume 2012 Article ID 713862 8 pages

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 256956 1 pagehttpdxdoiorg1011552013256956

EditorialAnalysis and Fate of Emerging Pollutants duringWater Treatment

Fei Qi1 Guang-Guo Ying2 Kaimin Shih3 Jolanta Kumirska4

Elif Pehlivanoglu-Mantas5 and Xiaojun Luo2

1 Beijing Key Lab for Source Control Technology of Water Pollution College of Environmental Science and EngineeringBeijing Forestry University No 35 Qinghua East Road Beijing 100083 China

2 State Key Laboratory of Organic Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of SciencesGuangzhou 510640 China

3Department of Civil Engineering The University of Hong Kong Pokfulam Road Hong Kong4Department of Environmental Analysis Faculty of Chemistry University of Gdansk Sobieskiego 1819 80-952 Gdansk Poland5 Environmental Engineering Department Istanbul Technical University Ayazaga Campus Maslak 34469 Istanbul Turkey

Correspondence should be addressed to Fei Qi qifeibjfueducn

Received 23 April 2013 Accepted 23 April 2013

Copyright copy 2013 Fei Qi et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Emerging pollutants defined as compounds that are notcurrently covered by existing water-quality regulations allover the world have not been studied widely before and arethought to be potential threats to environmental ecosystemsand human health This special issue compiles 5 excitingpapers which are very meticulously performed researches

Generally emerging pollutants encompass a diversegroup of compounds including pharmaceuticals drugs ofabuse personal-care products (PCPs) steroids and hor-mones surfactants perfluorinated compounds (PFCs) flameretardants industrial additives and agents gasoline additivesnew disinfection byproducts (DBPs) nanomaterials and thetoxic minerals

The analysis methods occurrence and fate of hormonaland endocrine disruptors compounds (EDCs) were dis-cussed in two papers of this special issue R Guedes-Alonsoet al determine the hormonal residues in treated water byultrahigh performance liquid chromatography-tandem massspectrometry (UPLC-MS) and evaluate the efficiency ofthe conventional wastewater treatment for the removal ofhormonal compounds Moreover Y Liu et al study anotherkinds of PPCPs named as phthalate esters that is typicalkind of EDCs The occurrence in a surface water and theremoval efficiency in a traditional drinking water treatmentpalnt are studied According to results of the two papers

the occurrence and fate of hormonal and EDCs in water orwastewater treatment are very clear

J Xing et al report a new wastewater treatment technol-ogy bioflocculation for the removal of sulfamethoxazole thatis a typical pharmaceutical in wastewater The performanceand the reaction mechanism of the biodegradation of sul-famethoxazole by the bioflocculation are discussed in depthMoreover the optimum reaction condition is obtained

The heavy metal and toxic mineral are also importantpollutants in the environment especially in the mining areaTwo papers of this issue are focused on this K Naeemul-lah et al report a green preconcentration method for thedetermination of cobalt and lead in water Y Liu et al do anovel research on the electrochemical reaction of pyrite as asimulation of the natural environmental

By compiling this special issue we hope to enrich ourreaders and researchers on the analysis and fate of emergingpollutants during water treatment

Fei QiGuang-Guo Ying

Kaimin ShihJolanta Kumirska

Elif Pehlivanoglu-MantasXiaojun Luo

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 419349 8 pageshttpdxdoiorg1011552013419349

Research ArticleOccurrence and Removal Characteristics of Phthalate Estersfrom Typical Water Sources in Northeast China

Yu Liu Zhonglin Chen and Jimin Shen

State Key Laboratory of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Jimin Shen shenjiminhiteducn

Received 21 December 2012 Accepted 3 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Yu Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The presence of phthalate esters (PAEs) in the environment has gained a considerable attention due to their potential impactson public health This study reports the first data on the occurrence of 15 PAEs in the water near the Mopanshan Reservoirmdashthenew and important water source of Harbin city in Northeast China As drinking water is a major source for human exposureto PAEs the fate of target PAEs in the two waterworks (Mopanshan Waterworks and Seven Waterworks) was also analyzed Theresults demonstrated that the total concentrations of 15 PAEs in the water near the Mopanshan Reservoir were relatively moderateranging from 3558 to 92265 ngL with the mean value of 29431 ngL DBP and DEHP dominated the PAE concentrations whichranged from 525 to 44982 ngL and 1289 to 65709 ngL respectivelyThe occurrence and concentrations of these compoundswereheavily spatially dependent Meanwhile the results on the waterworks samples suggested no significant differences in PAE levelswith the input of the raw waters Without effective and stable removal of PAEs after the conventional drinking water treatment inthe waterworks (258 to 765) the risks posed by PAEs through drinking water ingestion were still existing which should bepaid special attention to the source control in theMopanshan Reservoir and some advanced treatment processes for drinking watersupplies

1 Introduction

Phthalate acid esters a class of chemical compounds mainlyused as plasticizers for polyvinyl chloride (PVC) or to alesser extent other resins in different industrial activities areubiquitous in the environment and have evoked interest inthe past decade due to endocrine disrupting effects and theirpotential impacts on public health [1ndash3]

Worldwide production of PAEs is approximately 6 mil-lion tons per year [4] As PAEs are not chemically boundto the polymeric matrix in soft plastics they can enter theenvironment by losses during manufacturing processes andby leaching or evaporating from final products [5]Thereforethe occurrence and fate of specific PAEs in natural waterenvironments have been observed and also there are a lot ofconsiderable controversies with respect to the safety of PAEsin water [5ndash10]

Six PAE compounds including dimethyl (DMP) diethyl(DEP) dibutyl (DBP) butylbenzyl (BBP) di(2-ethylhexyl)

(DEHP) and di-n-octyl phthalate (DNOP) are classifiedas priority pollutants by the US Environmental ProtectionAgency (EPA) Though the toxicity of PAEs to humans hasnot been well documented for some years the Ministry ofEnvironmental Protection in China has regulated phthalatesas environmental pollutants In addition the standard inChina concerning analytical controls on drinkingwaters doesnot specifically identify any PAEs as organic pollutant indexesto be determined by the new drinking water standard in 2007(Standard for drinking water quality GB5749-2006) whichwas forced to be monitored for the drinking water supplies in2012 Consequently official data about the presence of thesepollutants in the aquatic environment of some cities are notavailable

Harbin the capital of Heilongjiang Province is a typicallyold industrial base and economically developed city with apopulation of over 3million inNortheast China As the newlyenabledwater source forHarbin cityMopanshanwaterworkssupply the whole city with drinking water through long

2 Journal of Analytical Methods in Chemistry

China

HarbinMopanshan

Reservoir

LongfengshanReservoir

Figure 1 Spatial distribution of the 16 sampling sites near the Mopanshan Reservoir in Northeast China

distance transfer from the Mopanshan Reservoir To theauthorsrsquo knowledge the occurrence and fate of PAEs in thewater near this area and its relative waterworks have notpreviously been examined

The objectives of this study were (i) to determine theoccurrence of PAEs and clarify the fate and distribution ofthe pollutants in the water source (ii) to examine the twowaterworks where traditional drinking water treatment stepwas evaluated on the PAEs removal efficiencies and (iii) toevaluate the potential for adverse effects of PAEs on humanhealth Therefore the investigation of PAEs in the water canprovide a valuable record of contamination in Harbin city

2 Materials and Methods

21 Chemical Fifteen PAEs standard mixture includingdimethyl phthalate diethyl phthalate diisobutyl phthalatedi-n-butyl phthalate di(4-methyl-2-pentyl) phthalate di(2-ethoxyethyl) phthalate di-n-amyl phthalate di-n-hexylphthalate butyl benzyl phthalate di(hexyl-2-ethylhexyl)phthalate di(2-n-butoxyethyl) phthalate dicyclohexyl phthal-ate di(2-ethylhexyl) phthalate di-n-nonyl phthalate di-n-octylphthalate at 1000 120583gmL each and surrogate standardsconsisting of diisophenyl phthalate di-n-phenyl phthal-ate and di-n-benzyl phthalate in a mixture solution of500120583gmL each were supplied by AccuStandard Inc Asthe internal standard benzyl benzoate was also purchasedfrom AccuStandard Inc All solvents (acetone hexane anddichloromethane) used were HPLC-grade and were pur-chased from J T Baker Co (USA) Anhydrous sodiumsulfate (Tianjin Chengguang Chemical Reagent Co China)was cleaned at 600∘C for 6 h and then kept in a desiccatorbefore use

22 Sample Collection and Preparation Harbin the capitalof Heilongjiang province in China imports nearly all of itsdrinking water from two sources the Mopanshan Reservoir

Raw water Coagulation sedimentation Filtration Tank

Sampling site Sampling site

Figure 2 Schematic diagram of the waterworks

(long-distance transport project) and the Songhua River (oldwater source)

Water samples from the Mopanshan Reservoir andMopanshan waterwork were collected in 2008 The locationsof the sampling sites near the Mopanshan Reservoir are pre-sented in Figure 1 as a comparison sampling from anotherHarbin water supplymdashSeven waterworks with water sourcefrom the SonghuaRiverwas performed in 2011 In eachwater-works with considering the hydraulic retention time threesets of raw water samples (influent) were taken and thenthe final finished waters (effluent) after the whole treatmentprocess were carried out for the collectionsThe flow diagramof the waterworks is shown in Figure 2

Samples were collected using 20 L glass jars from 05mbelow the water surface During the whole sampling processthe global position system was used to locate the samplingstations (details in Table 1) All samples were transferred tothe laboratory directly after sampling and stored at 4∘C priorto extraction within 2 d

Water samples were filtered under vacuum through glassfiber filters (07 120583mpore sizes) Prior to extraction each sam-ple was spiked with surrogate standards The water sampleswere extracted based on a classical liquid phase extractionmethod (USEPA method 8061) with slight modificationsBriefly 1 L of water samples was placed in a separating funneland extracted by means of mechanical shaking with 150mLdichloromethane and then with filtration on sodium sulfate(about 20 g) the organic extracts were concentrated usinga rotary evaporator The exchange of solvent was done byreplacing dichloromethane with hexane Finally they were

Journal of Analytical Methods in Chemistry 3

Table 1 Detailed descriptions of the sampling locations

Number Sampling site Name Latitude Longitude1 Lalin Jinsan Bridge Mangniu River E127∘0210158405310158401015840 N45∘510158404510158401015840

2 Xingsheng Town Gaojiatun Lalin River E127∘0610158401110158401015840 N44∘5110158405710158401015840

3 Dujia Town Shuguang Lalin River E127∘1010158404410158401015840 N44∘4810158404110158401015840

4 Shanhe Town Taipingchuan Lalin River E127∘1810158403610158401015840 N44∘4310158405010158401015840

5 Xiaoyang Town Qichuankou Lalin River E127∘2310158405410158401015840 N44∘3910158404610158401015840

6 Shahezi Town Mopanshan Reservoir E127∘3810158405910158401015840 N44∘2410158401710158401015840

7 Shahezi Town Gali Lalin River E127∘3510158401710158401015840 N44∘3110158405610158401015840

8 Chonghe Town Changcuizi Mangniu River E127∘4610158403610158401015840 N44∘3510158404610158401015840

9 Chonghe Town Xingguo Mangniu River E127∘3510158401710158401015840 N44∘3110158405710158401015840

10 Longfeng Town Mangniu River E127∘3510158401910158401015840 N44∘4310158404810158401015840

11 Changpu Town Zhonghua Mangniu River E127∘1610158403010158401015840 N45∘110158404210158401015840

12 Erhe Town Shuanghe Mangniu River E127∘1810158403210158401015840 N45∘410158402810158401015840

13 Zhiguang Town Songjiajie Mangniu River E127∘341015840310158401015840 N45∘110158402010158401015840

14 Zhiguang Town Wuxing Mangniu River E127∘2910158402010158401015840 N45∘010158404310158401015840

15 Changpu Town Xingzhuang Mangniu River E127∘1010158404210158401015840 N45∘410158403610158401015840

16 Yingchang Town Xingguang Lalin River E126∘551015840810158401015840 N45∘91015840010158401015840

reduced to 05mL under gentle nitrogen flow The internalstandard was added to the sample prior to instrumentalanalysis

23 Chemical Analysis The extracted compounds weredetermined by gas chromatography coupled to mass spec-trometer analysis as described in other publications [1112] Briefly extracted samples were injected into an Agilent6890 Series GC equipped with a DB-35MS capillary column(Agilent 30m times 025mm id 025120583m film thickness) andan Agilent 5973 MS detector operating in the selective ionmonitoring mode The column temperature was initially setat 70∘C for 1min then ramped at 10∘Cmin to 300∘C andheld constant for 10min The transfer line and the ion sourcetemperature were maintained at 280 and 250∘C respectivelyHelium was used as the carrier gas at a flow rate of 1mLminThe extracts (20 120583L) were injected in splitless mode with aninlet temperature of 300∘C

24 Quality Assurance and Quality Control All glasswarewas properly cleaned with acetone and dichloromethanebefore use Laboratory reagent and instrumental blanks wereanalyzed with each batch of samples to check for possiblecontamination and interferences Only small levels of PAEswere found in procedural blanks in some batches andthe background subtraction was appropriately performed inthe quantification of concentration in the water samplesCalibration curves were obtained from at least 3 replicateanalyses of each standard solution The surrogate standardswere added to all the samples to monitor matrix effectsRecoveries of PAEs ranged from 62 to 112 in the spikedwater and the surrogate recoveries were 751 plusmn 127 fordiisophenyl phthalate 723 plusmn 143 for di-n-phenyl phtha-late and 1026 plusmn 104 for di-n-benzyl phthalate in thewater samples The determination limits ranged from 6 to30 ngL A midpoint calibration check standard was injected

as a check for instrumental drift in sensitivity after every10 samples and a pure solvent (methanol) was injected as acheck for carryover of PAEs from sample to sample All theconcentrations were not corrected for the recoveries of thesurrogate standards

3 Results and Discussion

31 PAEs in Water Source The PAEs in the waters fromthe sampling sites near the Mopanshan Reservoir wereinvestigated and the results are presented in Table 2 Thesum15

PAEs concentrations ranged from 3558 to 92265 ngLwith the geometric mean value of 29431 ngL Among the15 PAEs detected in the waters DIBP DBP and DEHP weremeasured in all the samples with the average concentrationsbeing 1966 8014 and 17741 ngL respectively The threePAE congeners are important and popular addictives inmany industrial products including flexible PVC materialsand household products suggesting the main source of PAEcontaminants in the water [13] The correlations of the con-centration of DEHP DBP and DIBP with the concentrationsof total PAEs in the water samples are shown in Figure 3and a relatively significant correlation between sum

15

PAEs andDEHP concentration was found suggesting the importantpart played by DEHP in total concentrations of PAEs inthe water bodies near the Mopanshan Reservoir In otherwords the contribution of DEHP to total PAEs was higherthan that of other PAE congeners in the water samples Inaddition DMP DEP and DNOP with the mean value of140 284 and 541 ngL respectively only detected at somesampling sites and have also attracted much attention asthe priority pollutants by the China National EnvironmentalMonitoring Center On the contrary the concentrations of6 PAEs (DMEP BMPP BBP DBEP DCHP and DNP) werebelow detection limits in all the water samples near theMopanshan Reservoir which is easily explained in terms ofmuch lower quantities of present use in China

4 Journal of Analytical Methods in Chemistry

0 2000 4000 6000 80000

2000

4000

6000

Con

cent

ratio

ns (n

gL)

DEHP

119903 = 0885 119875 lt 001

sum15PAEs (ngL)

(a)

0 2000 4000 6000 80000

2000

4000

Con

cent

ratio

ns (n

gL)

sum15PAEs (ngL)

DBP

119903 = 0812 119875 lt 001

(b)

1000

500

0

0 2000 4000 6000 8000sum15PAEs (ngL)

DIBP

Con

cent

ratio

ns (n

gL)

119903 = 0724 119875 lt 001

(c)

Figure 3 Correlations of the concentration of the major PAEs (DEHP DBP and DIBP) with the concentrations of total PAEs in the watersamples

Table 2 Concentrations of 15 PAEs in water samples near the Mopanshan Reservoir

PAEs Abbreviation Water (ngL)Range Mean Frequency

Dimethyl phthalate DMP ndndash424 140 816Diethyl phthalate DEP ndndash550 284 1516Diisobutyl phthalate DIBP 400ndash6588 1966 1616Dibutyl phthalate DBP 525ndash44982 8014 1616bis(2-methoxyethyl)phthalate DMEP nd nd 016bis(4-methyl-2-pentyl)phthalate BMPP nd nd 016bis(2-ethoxyethyl)phthalate DEEP ndndash546 128 516Dipentyl phthalate DPP ndndash925 455 1016Dihexyl phthalate DHXP ndndash651 162 516Benzyl butyl phthalate BBP nd nd 016bis(2-n-butoxyethyl)phthalate DBEP nd nd 016Dicyclohexyl phthalate DCHP nd nd 016bis(2-ethylhexyl)phthalate DEHP 1289ndash65709 17741 1616Di-n-octyl phthalate DNOP ndndash4482 541 516Dinonyl phthalate DNP nd nd 016sum15

PAEs 3558ndash92265 29431 mdash

The distribution of 15 PAEs (sum15

PAEs) studied and6 US EPA priority PAEs (sum

6

PAEs including DMP DEPDIBP DBP DEHP and DNOP) in the waters from differentsampling sites are shown in Figure 4 There was an obviousvariation in the total sum

15

PAEs concentrations in water sam-ples near the Mopanshan Reservoir the concentrations ofsum6

PAEs from the same sampling sites varied from 2690 to90860 ngL with an average of 28686 ngL the distributionspectra of which observed for all the sampling sites weresimilar tosum

15

PAEsThe highest levels of PAEs contaminationwere seen on the sampling site 3 followed by some relativelyheavily polluted sites (site 16 13 9 10 and 11) indicating thatthese sites served as important PAE sources and the spatialdistribution of PAEs was site specific The levels in the watersexamined varied over a wide range especially in theMangniu

River near theMopanshan Reservoir (in some case overmorethan one order of magnitude) In general it should be notedthat there might be a relation of PAEs levels with the input oflocal waste such as sewage water food packaging and scrapmaterial near the sampling point which were found duringthe sampling period

32 PAE Congener Profiles in the Water Different PAE pat-terns may indicate different sources of PAEs Measurementof the individual PAE composition is helpful to track thecontaminant source and demonstrate the transport and fateof these compounds in water [11] The relative contributionsof the 9 detectable PAE congeners to thesum

15

PAEs concentra-tions in the water are presented in Figure 5 It is clear thatDEHP was the most abundant in the water samples with

Journal of Analytical Methods in Chemistry 5

0

500

1000

1500

4000

6000

8000

10000

Con

cent

ratio

ns (n

gL)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

sum15PAEssum6PAEs

Figure 4 Spatial distributions of the 16 sampling sites near theMopanshan Reservoir

the exception of site 2 3 and 11 contributions ranging from331 to 963 followed byDBP ranging from 21 to 363The results are consistent with the above data for overallanalysis that DBP and DEHP are the dominant componentsof the PAEs distribution pattern in each sampling site whichreflected the different pattern of plastic contaminant inputduring the sampling period Similarly DIBP and DBP areused in epoxy resins or special adhesive formulations withthe different proportions of these two PAE congeners whichwere also the important indicator of the information pollutedby PAEs for the sampling locations Although the limitedsample number draws only limited conclusions there is stillreason to note that a leaching from the plastic materials intothe runoff water is possible and that water runoff from thecontaminated water is a burden pathway from differentsources of PAEs [14]

33 Comparison with Other Water Bodies Comparison withthe total PAEs concentrations is nevertheless very limited dueto the different analysis compounds However the individualPAE namely DBP and DEHP is by far the most abundantin other researches and it is possible to make a camparisonwith our findings In this case the results of DBP and DEHPconcentrations published in literatures for kinds of waterbodies are presented together in Table 3

The DEHP and DBP concentrations of the present studyshowed to some extent lower concentration levels than thosereported in the other water bodies in China In comparisonthe results were comparable or similar to those from theexaminations described in other foreign countries For exam-ple as shown in Table 3 the DEHP concentrations were sim-ilar to the surface waters from the Netherlands and Italydescribed in the literature Meanwhile these concentrationsin this study were quite lower than the Yangtze River andSecond Songhua River in China

0

20

40

60

80

100

DEEP DPP DHXP DEHP DNOP DBP

DIBP DEP DMP

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

Com

posit

ion

()

Figure 5 PAE composition of thewater samples in 16 sampling sites

In conclusion as compared to the results of other studiesthe waters near the Mopanshan Reservoir were moderatelypolluted by PAEs Therefore there is a definite need to set upa properly planned and systematic approach to water controlnear the Mopanshan Reservoir

34 PAE Levels in the Waterworks The Mopanshan Water-works (MPSW) equipped essentially with the water sourceof the Mopanshan Reservoir has been investigated in orderto assess the fate of the PAEs during the drinking watertreatment process For comparison a sampling campaign forthe determination of PAEs levels in the Seven Waterworks(SW waterworks with the old water source of the SonghuaRiver) was carried out Both waterworks operate coagulationsedimentation and followed by filtration treatment processwhich are typical traditional drinking water treatment

The measured concentrations in the raw and finishedwater of the two investigated waterworks are shown inFigure 6 Six out of fifteen PAEs were detected in the fin-ished water from the two waterworks The detected PAEswere DMP DEP DIBP DBP DEHP and DNOP and theother investigated phthalates are of minor importance withconcentrations all below the limit of detection As showin Figure 6 the measured concentrations of the analyzedPAEs in the finished water of the two waterworks variedstronglyThemost important compound in the finishedwaterwas DEHP with the mean concentration of 34737 and40592 ngL for the MPSW and SW respectively suggestingthe highest relative composition of total PAE concentrationsin the drinking water

For the raw water from the different water sources DMPand DIBP concentrations in the MPSW were much lowerthan the ones in the SW and the concentrations of DEPDBP DEHP andDEHPwere relatively comparable in the two

6 Journal of Analytical Methods in Chemistry

Table 3 Comparison of the concentrations of DEHP and DBP in the water bodies (ngL)

Location DEHP DBP ReferenceRange Median Mean Range Median Mean

Surface water Germany 330ndash97800 2270 mdash 120ndash8800 500 mdash [14]Surface water the Netherlands ndndash5000 320 mdash 66ndash3100 250 mdash [15]Seine River estuary France 160ndash314 mdash mdash 67ndash319 mdash mdash [16]Tama River Japan 13ndash3600 mdash mdash 8ndash540 mdash mdash [17]Velino River Italy ndndash6400 mdash mdash ndndash44300 mdash mdash [2]Surface water Taiwan ndndash18500 mdash 9300 1000ndash13500 mdash 4900 [18]Surface water Jiangsu China 556ndash156707 mdash mdash 16ndash58575 mdash mdash [19]Yangtze River mainstream China 3900ndash54730 mdash mdash ndndash35650 mdash mdash [20]Middle and lower Yellow River China 347ndash31800 mdash mdash ndndash26000 mdash mdash [21]Second Songhua River China ndndash1752650 370020 mdash ndndash5616800 mdash 717240 [22]Urban lakes Guangzhou China 87ndash630 170 240 940ndash3600 1990 2030 [11]Xiangjiang River China 620ndash15230 mdash mdash mdash mdash mdash [23]This study 1289ndash65709 6710 17741 525ndash44982 1103 8014

0

500

1000

100001200014000

0

20

40

60

80

100

Raw waterFinished waterRemoval

Rem

oval

()

Con

cent

ratio

ns (n

gL)

DMP DEP DIBP DBP DEHP DNOP

(a)

Raw waterFinished waterRemoval

0

500

1000

1500

2000

100001200014000

0

20

40

60

80

100C

once

ntra

tions

(ng

L)

Rem

oval

()

DMP DEP DIBP DBP DEHP DNOP

(b)

Figure 6 PAEs detected in the water samples from the MPSW (a) and SW (b)

waterworks The removal of PAEs by these two waterworksranged from 258 to 765 which varied significantly with-out stable removal efficienciesThe lower removal efficienciesfor DMP and DNOP were observed in the SW with theremoval less than 30 For both the waterworks no soundremoval efficiencies were obtained for the PAEs indicatingthat the traditional drinking water treatment cannot showgood performance to eliminate these micro pollutants whichhas nothing to do with the type of the water source

Traditional drinking water treatment focuses on dealingwith the particles and colloids in terms of physical processesMany studies of the environmental fates of PAEs have demon-strated that oxidation or microbial action is the principalmechanism for their removal in the aquatic systems [24ndash26]Therefore the treatment process should be the combinationswith the key techniques for removing PAEs from the waterOn the other hand since the removal efficiencies of PAEs by

these advance drinking water treatments in waterworks hasnot been systematically studied to date further research inthis direction would seem to be required

35 Exposure Assessment of PAEs in Water To evaluate thepotential and adverse effects of PAEs quality guidelines forsurface water and drinking water standard were used Theresults indicated that the mean concentrations of DBP andDEHP at levels were well below the reference doses (RfD)regarded as unsafe by the EPA for the surface water Thelevels were not also above the RfD recommended by China(Environmental Quality Standard for SurfaceWater of ChinaGB3838-2002) On the other hand the amounts of DEHPpresent in public water supplies should be lower than thedrinkingwater standard (0006mgL for EPA and 0008mgLfor China) According to the results the concentrations of

Journal of Analytical Methods in Chemistry 7

DEHP in drinkingwater samples from theMPSWwere lowerthan the limited value

PAEs are also considered to be endocrine disruptingchemicals (EDCs) whose effects may not appear until long-term exposure According to the results PAEs were detectedin the drinking water constantly ingested in daily life indi-cating that drinking water is an important source of humanexposure to PAEs contaminants Assuming a daily waterconsumption rate of 2 L and an average body weight of 60 kgfor adults the average daily intake of DEHP DBP and DIBPby way of drinking water from MPSW was calculated to be1158 1352 and 81 ngkgd respectively In comparison thevalues of SW with the water source of the Songhua Riverwere relatively higher with the calculated results of 1353140 and 155 ngkgd for DEHP DBP and DIBP respectivelyIn this study the estimated daily intake levels of DEHPfrom the drinking water were quite lower than the RfDof 20000 ngkgd released by the EPA However some ofPAEs are partly metabolised in the organism and futureexperiments should be focused on determining the potentialeffects of the metabolites [27]

Currently treated water from the Songhua River is fornonpotable uses and MPSW is the exclusive waterworks runfor the water supply of Harbin city However populationgrowth and drought cycle are limited by the availability of rawwater from theMopanshan Reservoir Tomeet the increasingdemand local and regional water authorities have begun acampaign of second water supply project from the SonghuaRiver again which needs the protection of the Songhua Riverand advanced water treatment for the source

4 Conclusions

This study provided the first detailed data on the contami-nation status of 15 PAEs in the water near the MopanshanReservoir The concentration range of 15 PAEs in the sampleswas from 3558 to 92265 ngL with the mean value of29431 ngL DEHP andDBPwere themain pollutants among15 PAEs accounting for the main watershed pollution Theoccurrence and distribution of PAEs from different samplingsites in the water source varied largely suggesting that thespatial distribution of PAEs was site specific In additionthe monitoring of PAEs in the waterworks also showed thatPAEs can be detected in the drinking water and certaintoxicological risks to drinking water consumers were foundThese results reported here contribute to an understandingof how PAE contaminants are distributed in the new watersource and the waterworks in Harbin city as well as forminga basis for further modeling risk assessment and selection ofdrinking water treatment technology

In conclusion the results implied that no urgent reme-diation measures were required with respect to PAEs in thewaters However the ecological and health effects of thesesubstances through drinkingwater at the relatively lower con-centrations still need further notice in light of their possiblebiological magnifications Therefore the long-term sourcecontrol in the water and adding advanced treatment processfor drinking water supplies should be given special attentionin this area

Acknowledgments

This work was supported by the National Natural ScienceFoundation of China (1077029) the Funds for CreativeResearch Groups of China (Grant no 51121062) the NationalNatural Science Foundation of China (51078105) and theOpen Project of the State Key Laboratory of Urban WaterResource and Environment Harbin Institute of Technology(no QA201019)

References

[1] M Nikonorow H Mazur and H Piekacz ldquoEffect of orallyadministered plasticizers and polyvinyl chloride stabilizers inthe ratrdquo Toxicology and Applied Pharmacology vol 26 no 2 pp253ndash259 1973

[2] M Vitali M Guidotti G Macilenti and C Cremisini ldquoPhtha-late esters in freshwaters asmarkers of contamination sourcesmdasha site study in ItalyrdquoEnvironment International vol 23 no 3 pp337ndash347 1997

[3] G Latini C de Felice G Presta et al ldquoIn utero exposure todi-(2-ethylhexyl)phthalate and duration of human pregnancyrdquoEnvironmental Health Perspectives vol 111 no 14 pp 1783ndash17852003

[4] C E Mackintosh J A Maldonado M G Ikonomou and F AP C Gobas ldquoSorption of phthalate esters and PCBs in a marineecosystemrdquo Environmental Science and Technology vol 40 no11 pp 3481ndash3488 2006

[5] M Clara G Windhofer W Hartl et al ldquoOccurrence of phtha-lates in surface runoff untreated and treated wastewater andfate during wastewater treatmentrdquo Chemosphere vol 78 no 9pp 1078ndash1084 2010

[6] M M Abdel Daiem J Rivera-Utrilla R Ocampo-Perez J DMendez-Dıaz andM Sanchez-Polo ldquoEnvironmental impact ofphthalic acid esters and their removal fromwater and sedimentsby different technologiesmdasha reviewrdquo Journal of EnvironmentalManagement vol 109 pp 164ndash178 2012

[7] L Chen Y Zhao L Li B Chen and Y Zhang ldquoExposureassessment of phthalates in non-occupational populations inChinardquo Science of the Total Environment vol 427-428 pp 60ndash69 2012

[8] M J Teil M Blanchard andM Chevreuil ldquoAtmospheric fate ofphthalate esters in an urban area (Paris-France)rdquo Science of theTotal Environment vol 354 no 2-3 pp 212ndash223 2006

[9] P Roslev K Vorkamp J Aarup K Frederiksen and P HNielsen ldquoDegradation of phthalate esters in an activated sludgewastewater treatment plantrdquo Water Research vol 41 no 5 pp969ndash976 2007

[10] J Gasperi S Garnaud V Rocher and R Moilleron ldquoPrioritypollutants in wastewater and combined sewer overflowrdquo Scienceof the Total Environment vol 407 no 1 pp 263ndash272 2008

[11] F Zeng K Cui Z Xie et al ldquoOccurrence of phthalate estersin water and sediment of urban lakes in a subtropical cityGuangzhou South Chinardquo Environment International vol 34no 3 pp 372ndash380 2008

[12] F Zeng K Cui Z Xie et al ldquoPhthalate esters (PAEs) emergingorganic contaminants in agricultural soils in peri-urban areasaround Guangzhou Chinardquo Environmental Pollution vol 156no 2 pp 425ndash434 2008

[13] G Wildbrett ldquoDiffusion of phthalic acid esters from PVC milktubingrdquo Environmental Health Perspectives vol 3 pp 29ndash351973

8 Journal of Analytical Methods in Chemistry

[14] H Fromme T Kuchler T Otto K Pilz J Muller and AWenzel ldquoOccurrence of phthalates and bisphenol A and F inthe environmentrdquoWater Research vol 36 no 6 pp 1429ndash14382002

[15] A D Vethaak J Lahr S M Schrap et al ldquoAn integrated assess-ment of estrogenic contamination and biological effects in theaquatic environment ofTheNetherlandsrdquoChemosphere vol 59no 4 pp 511ndash524 2005

[16] C Dargnat M Blanchard M Chevreuil andM J Teil ldquoOccur-rence of phthalate esters in the Seine River estuary (France)rdquoHydrological Processes vol 23 no 8 pp 1192ndash1201 2009

[17] T Suzuki K Yaguchi S Suzuki and T Suga ldquoMonitoring ofphthalic acid monoesters in river water by solid-phase extrac-tion and GC-MS determinationrdquo Environmental Science andTechnology vol 35 no 18 pp 3757ndash3763 2001

[18] S Y Yuan C Liu C S Liao and B V Chang ldquoOccurrenceand microbial degradation of phthalate esters in Taiwan riversedimentsrdquo Chemosphere vol 49 no 10 pp 1295ndash1299 2002

[19] B Li C Qu and J Bi ldquoIdentification of trace organic pollutantsin drinking water and the associated human health risks inJiangsu Province Chinardquo Bulletin of Environmental Contami-nation and Toxicology pp 1ndash5 2012

[20] F Wang X Xia and Y Sha ldquoDistribution of phthalic acidesters in Wuhan section of the Yangtze River Chinardquo Journalof Hazardous Materials vol 154 no 1ndash3 pp 317ndash324 2008

[21] Y J Sha X H Xia and X Q Xiao ldquoDistribution characters ofphthalic acid ester in the waters middle and lower reaches ofthe Yellow Riverrdquo China Environmental Science vol 26 no 1pp 120ndash124 2006

[22] J Lu L-B Hao C-Z Wang W Li R-J Bai and D YanldquoDistribution characteristics of phthalic acid esters in middleand lower reaches of no 2 Songhua Riverrdquo EnvironmentalScience amp Technology vol 12 article 014 2007

[23] X J Zhu and Y Y Qiu ldquoMeasuring the phthalates of xiangjiangriver using liquid-liquid extraction gas chromatographyrdquoAdvanced Materials Research vol 301 pp 752ndash755 2011

[24] B L Yuan X Z Li and N Graham ldquoAqueous oxida-tion of dimethyl phthalate in a Fe(VI)-TiO

2

-UV reaction sys-temrdquoWater Research vol 42 no 6-7 pp 1413ndash1420 2008

[25] Z Yunrui ZWanpeng L FudongW Jianbing and Y ShaoxialdquoCatalytic activity of RuAl2O3 for ozonation of dimethylphthalate in aqueous solutionrdquo Chemosphere vol 66 no 1 pp145ndash150 2007

[26] H N Gavala U Yenal and B K Ahring ldquoThermal andenzymatic pretreatment of sludge containing phthalate estersprior tomesophilic anaerobic digestionrdquoBiotechnology and Bio-engineering vol 85 no 5 pp 561ndash567 2004

[27] Y Guo Q Wu and K Kannan ldquoPhthalate metabolites in urinefrom China and implications for human exposuresrdquo Environ-ment International vol 37 no 5 pp 893ndash898 2011

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 210653 8 pageshttpdxdoiorg1011552013210653

Research ArticleSimultaneous Determination of Hormonal Residuesin Treated Waters Using Ultrahigh Performance LiquidChromatography-Tandem Mass Spectrometry

Rayco Guedes-Alonso Zoraida Sosa-Ferrera and Joseacute Juan Santana-Rodriacuteguez

Departamento de Quımica Universidad de Las Palmas de Gran Canaria 35017 Las Palmas de Gran Canaria Spain

Correspondence should be addressed to Jose Juan Santana-Rodrıguez jsantanadquiulpgces

Received 28 December 2012 Accepted 7 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Rayco Guedes-Alonso et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

In the last years hormone consumption has increased exponentially Because of that hormone compounds are considered emergingpollutants since several studies have determinted their presence in water influents and effluents of wastewater treatment plants(WWTPs) In this study a quantitative method for the simultaneous determination of oestrogens (estrone 17120573-estradiol estriol17120572-ethinylestradiol and diethylstilbestrol) androgens (testosterone) and progestogens (norgestrel andmegestrol acetate) has beendeveloped to determine these compounds in wastewater samples Due to the very low concentrations of target compounds in theenvironment a solid phase extraction procedure has been optimized and developed to extract and preconcentrate the analytesDetermination and quantification were performed by ultrahigh performance liquid chromatography-tandem mass spectrometry(UHPLC-MSMS) The method developed presents satisfactory limits of detection (between 015 and 935 ngsdotLminus1) good recoveries(between 73 and 90 for the most of compounds) and low relative standard deviations (under 84) Samples from influents andeffluents of two wastewater treatment plants of Gran Canaria (Spain) were analyzed using the proposed method finding severalhormones with concentrations ranged from 5 to 300 ngsdotLminus1

1 Introduction

In general it is supposed that more than 100000 differentchemical compounds can be introduced in the Environmentmany of them in very small quantity However a lot of thesecompounds are not included as pollutants in the legislationAlthough these compounds named emerging pollutants arenot regulated as pollutants they probably will be in the futurebecause of their potential negative effect in the ecosystem For20 years many articles have reported the presence of theseldquonew compoundsrdquo in wastewater [1 2]

The emerging pollutant origin is mainly anthropogenicconsidering that the majority of these compounds are bio-logically active substances that are synthesized to use themin agriculture industry and medicine The main source ofthese emerging pollutants is the residual urbanwaters and thewastewater treatment plants effluents because many of these

WWTPs are not designed or optimized to treat this kind ofcompounds [3]

Hormones are one of the most potent endocrine disrupt-ing compounds as well as are considered also as emergingpollutants Hormones can be differentiated in oestrogensandrogens and progestogens Some of them have limits intheir use but not a specific legislation [4]

The main characteristic of these pollutants is that it isnot necessary to remain in the environment to cause negativeeffects in view of the fact that their constant introduction init offsets their removal or degradation [5]

The steroid hormones help controlling the metabolisminflammations immunological functions water and salt bal-ance sexual development and the capacity of withstandingillnesses [6] The term steroid can be used for naturalhormones produced by the body as well as for artificiallyproduced medicines that increase the natural steroid effect

2 Journal of Analytical Methods in Chemistry

In the last 50 years the natural and synthetic hormoneworldwide consumption has grown as much as in humanmedicine as in cattle farming and they become the mostprescribed medicines [7]

A significant quantity of consumed oestrogens leaves theorganism through excretions For example 17120573-estradiol (E2)is oxidized rapidly becoming an estrone (E1) that can turninto estriol afterwards (E3) Besides the 17120572-ethinyl estradiol(EE) is excreted as conjugated [8]

With regard to emission sources in the first place arethe wastewater treatment plants (WWTPs) [9] and secon-darily cattle waste such as those leachates from dung anduncontrolled dumping [10] Several studies made in theWWTPs have reported that the treatment plants are capableof eliminating around 60 of hormones [11ndash13]

The identification of hormone residues in environmentis of special interest because knowledge of these compoundsis a requirement to take measures in order to regulate andminimize their environmental impact

However measurement of hormone residues is a verydifficult task not only due to the difficulty in measuringvery low concentration but also due to a very complexityof the samples Therefore use of mass spectrometer (MS)as detector coupled with chromatography techniques hasbecome a powerful method for the analysis of these typesof compounds at trace levels [14ndash17] Consequently LC-MSMS is the principally chosen technique One of the mainadvantages of LC-MSMS is its ability to analyze hormoneswithout derivatization (necessary in GC) or the need ofhydrolyze the conjugated form

Due to low level concentration of these compounds inenvironmental water it is necessary to apply an extractionand preconcentration method prior to LC analysis The mostused technique of extraction and preconcentration methodfor liquid samples is the solid phase extraction (SPE) [18ndash20]

The objective of this study is to develop a rapid and simpleprocedure of extraction preconcentration and determina-tion of four steroid oestrogens (estrone (E1) 17120573-estradiol(E2) estriol (E3) and 17120572-ethinylestradiol (EE)) one non-steroidal oestrogen the diethylstilbestrol (DES) one andro-gen the testosterone (TES) and two synthetic progestogensnorgestrel (NOR) and megestrol acetate (MGA) (Table 1)based on solid phase extraction and ultrahigh performanceliquid chromatography-tandem mass spectrometry (SPE-UHPLC-MSMS) The developed method was applied tothe identification and quantification of these compoundsin wastewater samples obtained from the influents andeffluents of two wastewater treatment plants (WWTPs) ofGran Canaria (Spain) They presented different methodsof wastewater treatments WWTP 1 presented a traditionalmethod based on activated sludge while WWTP 2 used amembrane bioreactor technique

2 Materials and Methods

21 Reagents All of the hormonal compounds usedwere pur-chased from Sigma-Aldrich (Madrid Spain) Stock solutionscontaining 1000mgsdotLminus1 of each analyte were prepared by

dissolving the compound inmethanol and the solutionswerestored in glass-stoppered bottles at 4∘C prior to use Workingaqueous standard solutions were prepared daily Ultrapurewater was provided by a Milli-Q system (Millipore BedfordMA USA) HPLC-grade methanol LC-MS methanol andLC-MS water as well as the ammonia and the ammoniumacetate used to adjust the pH of the mobile phases wereobtained from Panreac Quımica (Barcelona Spain)

22 Sample Collection Water samples were collected fromthe effluents of twowastewater treatment plants located in thenorthern area of Gran Canaria in May and August of 2012WWTP 1 used a conventional activated sludge treatmentsystem while WWTP 2 employed a membrane bioreactortreatment system The samples were collected in 2 L amberglass bottles that were rinsed beforehand with methanol andultrapurewater Samples were purified through filtrationwithfibreglass filters and then with 065 120583m membrane filters(Millipore Ireland) The samples were stored in the dark at4∘C and extracted within 48 hours

23 Instrumentation For the SPE optimization the instru-ment used was an ultrahigh performance liquid chromatog-raphy with fluorescence detector (UHPLC-FD) system con-sisting of an ACQUITYQuaternary Solvent Manager (QSM)used to load samples and wash and recondition the analyticalcolumn an autosampler a column manager and a fluores-cence detector with excitation and emission wavelengths of280 and 310 nm respectively all fromWaters (Madrid Spain)

The analysis of wastewater samples was performed ina UHPLC-MSMS system from Waters (Madrid Spain)similar to the described above with a 2777 autosamplerequipped with a 25120583L syringe and a tray to hold 2mLvials and an ACQUITY tandem triple quadrupole (TQD)mass spectrometer with an electrospray ionization (ESI)interface All Waters components (Madrid Spain) werecontrolled using the MassLynx Mass Spectrometry SoftwareElectrospray ionisation parameters were fixed as followsthe capillary voltage was 3 kV in positive mode and minus2 kVin negative mode the source temperature was 150∘C thedesolvation temperature was 500∘C and the desolvation gasflow rate was 1000 Lhr Nitrogen was used as the desolvationgas and argon was employed as the collision gas

The detailed MSMS detection parameters for each hor-monal compound are presented in Table 2 and were opti-mised by the direct injection of a 1mgsdotLminus1 standard solutionof each analyte into the detector at a flow rate of 10 120583Lsdotminminus1

24 Chromatographic Conditions For the SPE optimizationthe analytical column was a 50mm times 21mm ACQUITYUHPLCBEHWaters C

18columnwith a particle size of 17120583m

(Waters Chromatography Barcelona Spain) operating at atemperature of 30∘C Analytes separation was carried outemploying the following gradient starting at 55 45 (vv)water methanol for 1 minute During 3 minutes it changedto 50 50 (vv) and stayed for 25 minutes more Finally cameback to initial conditions in 1 minute and stayed for 15

Journal of Analytical Methods in Chemistry 3

Table 1 List of hormonal compounds pKa values chemical structure and retention times

Compound pKa [21] Structure 119905119877

(min)

E3 Estriol 103

HO

OH

OH

H H

H096

E2 17120573-estradiol 103

HO

OH

H H

H218

EE 17120572-ethinylestradiol 103

HO

HO

H H

H223

E1 Estrone 103

HO

O

H

H H220

DES Diethylstilbestrol 102

HO

OH

235

TES Testosterone 151

OH

OH H

H240

MGA Megestrol acetate

O

O

O

OH

H

H306

NOR Levonorgestrel 131

OH

O

H

H

H

H263

minutes Therefore the analysis took 9 minutes at a flow of05mLsdotminminus1

For the analysis of real samples aUHPLC-MSMS systemwas used The analytical column was the same and themobile phase was water and methanol adjusted with a bufferconsisting in 01 vv ammonia and 15mM of ammoniumacetate The analysis was performed in gradient mode at aflow rate of 03mLsdotminminus1The gradient started at 50 50 (vv)mixture of water methanol which changed to 25 75 (vv) in3 minutes and returned to 50 50 in 1 minute more Finallythe gradient stayed calibrating for another 15 minutes moreThe sample volume injected was 5120583L

3 Results and Discussion

31 Optimization of Solid-Phase Extraction (SPE) There area number of parameters that affect SPE procedure such as

type of sorbent pH ionic strength sample and desorptionvolumes and wash step To optimize these parameters itused Milli-Q water spiked with a solution of fluorescenceoestrogens (estriol 17120573-estradiol and 17120572-ethinylestradiol)to obtain a final concentration of 250120583gsdotLminus1

The first parameter to optimize is the choice of sorbentsince it controls the selectivity affinity and capacity overanalytes In this study the SPE cartridges used were OASISHLB SepPak C

18(both from Waters Madrid Spain) and

BondElut ENV (fromAgilent Madrid Spain) Keeping otherparameters fixed (ionic strength of 0 sample volume of100mL) the cartridges were studied at three different pHs(5 8 and 11) From the results obtained it can be observedthat the better signals are found for SepPak C

18cartridge

(Figure 1)After choosing the optimum cartridge we used an initial

experimental design of 23 to study the influence of pH ionic

4 Journal of Analytical Methods in Chemistry

Table 2 Mass spectrometer parameters for the determination of target analytes

Compound Precursor ion(mz)

Capillary voltage(Ion mode)

Quantification ionmz(collision potential V)

Quantification ionmz(collision potential V)

E3 2872 minus65V (ESI minus) 1710 (37) 1452 (39)E2 2712 minus65V (ESI minus) 1451 (40) 1831 (31)EE 2952 minus60V (ESI minus) 1450 (37) 1589 (33)E1 2692 minus65V (ESI minus) 1450 (36) 1430 (48)DES 2671 minus50V (ESI minus) 2371 (29) 2511 (25)TES 2892 38V (ESI +) 1870 (18) 1040 (21)MGA 3855 30V (ESI +) 2673 (15) 2242 (30)NOR 3132 38V (ESI +) 1090 (26) 2451 (18)

0

500

1000

1500

2000

2500

E3 E2 EE

Peak

area

Cartridge optimizationOASIS HLB pH = 5

OASIS HLB pH = 8

OASIS HLB pH = 11SepPak C18 pH = 5

SepPak C18 pH = 8

SepPak C18 pH = 11BondElut ENV pH = 5

BondElut ENV pH = 8

BondElut ENV pH =11

Figure 1 Optimization of SPE cartridges

strength and sample volume over extraction process Theexperimental design was obtained using Statgraphics Plussoftware 51 and the statistics study was done with IBM SPSSStatistics 19 We assessed two levels and three parameters pH(3 and 8) ionic strength (0 and 30 of NaCl) and samplevolume (50 and 250mL) to obtain the influence of eachparameter and the variable correlation to each other In thisstudy it is observed that the ionic strength and sample volumehad the major influence on the recoveries of the analytesFor that a 32 factorial design to optimize these two variablesat three levels per parameter (0 15 and 30 of NaCl forionic strength and 50 100 y 250mL for sample volume) wasused Figure 2 shows the response surface obtained for theestriol and 17120572-ethinylestradiol The results obtained showedthat an increment of the ionic strength did not producean increase in the response area of the compound and theoptimum volume was 250mL Because of that a solutionwithout salt addition and 250mL of sample volume waschosen Finally the desorption volume (1mLofmethanol and2mL of methanol in one and two steps) and wash-step (5mL

ofMilli-Q water and 5mL ofMilli-Q water with 5 and 10 ofmethanol vv) were assayed to complete the optimization ofthe SPE process The optimum values were 2mL of methanolin one step and 5mL of Milli-Q water without methanolrespectively

In accordance with the obtained results the optimumconditions for SPE procedure were SepPak C

18cartridge

250mL of sample at pH = 8 and 0 of NaCl desorptionwith 2mL of methanol in one step and wash step with5mL of Milli-Q water In these conditions we achieved apreconcentration factor of 125 In Figure 3 a chromatogramwith the optimum conditions is shown where the peaksof all compounds in their corresponding transitions can beobserved

32 Analytical Parameters Because of the SPE optimizationthat was done only with fluorescent compounds (estriol 17120573-estradiol and 17120572-ethinylestradiol) it was necessary to studythe recoveries of all the hormonal compounds using theoptimized SPE-UHPLC-MSMSmethod All the compoundsunder study showed good recoveries over 73 except thediethylstilbestrol with a recovery of 507

A calibration curve was used for the quantification ofthe analytes by diluting the stock solution of each analyteinto the samples to concentrations ranging between 1 and100 120583gsdotLminus1 Analysis was conducted by UHPLC-MSMS andlinear calibration plots for each analyte (1199032 gt 099) wereobtained based on their chromatographic peak areas

The limit of detection (LOD) and the limit of quantifi-cation (LOQ) for each compound were calculated from thesignal-to-noise ratio of each individual peak The LOD wasdefined as the lowest concentration that gave a signal-to-noiseratio that was greater than 3 The LOQ was defined as thelowest concentration that gave a signal to noise ratio that wasgreater than 10The LODs ranged from015 to 935 ngsdotLminus1 andthe LOQs ranged from 049 to 3118 ngsdotLminus1

The performance and reliability of the process werestudied by determining the repeatability of the quantificationresults for all target analytes under the described conditionsusing six samples (119899 = 6) The relative standard deviations(RSDs) were lower than 84 in all cases indicating a

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 2: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Analysis and Fate of Emerging Pollutantsduring Water Treatment

Journal of Analytical Methods in Chemistry

Analysis and Fate of Emerging Pollutantsduring Water Treatment

Guest Editors Fei Qi Guang-Guo Ying Kaimin ShihJolanta Kumirska Elif Pehlivanoglu-Mantas and Xiaojun Luo

Copyright copy 2013 Hindawi Publishing Corporation All rights reserved

This is a special issue published in ldquoJournal of Analytical Methods in Chemistryrdquo All articles are open access articles distributed underthe Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium providedthe original work is properly cited

Editorial Board

M Abdel-Rehim SwedenH Y Aboul Enein EgyptSilvana Andreescu USAA N Anthemidis GreeceA N Araujo PortugalR W Arndt SwitzerlandAna Cristi B Dias BrazilPierangelo Bonini ItalyArthur C Brown USAAntony C Calokerinos GreeceRicardo J Cassella BrazilXin-Sheng Chai ChinaO Chailapakul ThailandXingguo Chen ChinaC Collombel FranceW T Corns UKMiguel de la Guardia SpainIvonne Delgadillo PortugalE Dellacassa UruguayCevdet Demir TurkeyM Bonner Denton USAGregory W Diachenko USAM E Diaz-Garcia SpainDieter M Drexler USAJianxiu Du ChinaJenny Emneus DenmarkG Eppe BelgiumJosep Esteve-Romero SpainO Fatibello-Filho BrazilPaul S Francis AustraliaJuan F Garcia-Reyes SpainC Georgiou GreeceKate Grudpan ThailandR Haeckel Germany

Arafa I Hamed EgyptKaroly Heberger HungaryBernd Hitzmann GermanyChih-Ching Huang TaiwanI Isildak TurkeyJaroon Jakmunee ThailandXiue Jiang ChinaSelhan Karagoz TurkeyHiroyuki Kataoka JapanSkip Kingston USAChristos Kontoyannis GreeceR Kowalski PolandAnnamalai S Kumar IndiaIlkeun Lee USAJoe Liscouski USAEulogio J Llorent-Martinez SpainMercedes G Lopez MexicoMiren Lopez de Alda SpainLarisa Lvova ItalyJos Carlos Marques PortugalChristophe A Marquette FranceJean Louis Marty FranceSomenath Mitra USASerban C Moldoveanu USAMaria B Montenegro PortugalG A Nagana Gowda USAMilka Neshkova BulgariaB Nikolova-Damyanova BulgariaSune Nygaard DenmarkC K OrdquoSullivan SpainGangfeng Ouyang ChinaSibel A Ozkan TurkeyVeronica Pino SpainKrystyna Pyrzynska Poland

Jose B Quintana SpainMohammad A Rashid BangladeshD P S Rathore IndiaPablo Richter ChileFabio R P Rocha BrazilErwin Rosenberg AustriaGiuseppe Ruberto ItalyAntonio R Medina SpainBradley B Schneider CanadaGuoyue Shi ChinaJesus S Gandara SpainHana Sklenarova Czech RepublicN H Snow USAP B Stockwell UKF O Suliman OmanIt-Koon Tan SingaporeD G Themelis GreeceNilgun Tokman TurkeyNelson Torto South AfricaMarek Trojanowicz PolandParis Tzanavaras GreeceBengi Uslu TurkeyKrishna K Verma IndiaAdam Voelkel PolandFang Wang USAHai-Long Wu ChinaHui-Fen Wu TaiwanQingli Wu USAMengxia Xie ChinaRongda Xu USAXiu-Ping Yan ChinaLu Yang CanadaC Yin China

Contents

Analysis and Fate of Emerging Pollutants during Water Treatment Fei Qi Guang-Guo Ying Kaimin ShihJolanta Kumirska Elif Pehlivanoglu-Mantas and Xiaojun LuoVolume 2013 Article ID 256956 1 page

Occurrence and Removal Characteristics of Phthalate Esters from Typical Water Sources in NortheastChina Yu Liu Zhonglin Chen and Jimin ShenVolume 2013 Article ID 419349 8 pages

Simultaneous Determination of Hormonal Residues in Treated Waters Using Ultrahigh PerformanceLiquid Chromatography-Tandem Mass Spectrometry Rayco Guedes-Alonso Zoraida Sosa-Ferreraand Jose Juan Santana-RodrıguezVolume 2013 Article ID 210653 8 pages

Removal Efficiency and Mechanism of Sulfamethoxazole in Aqueous Solution by Bioflocculant MFXJie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei WeiVolume 2013 Article ID 568614 8 pages

Pyrite Passivation by Triethylenetetramine An Electrochemical Study Yun Liu Zhi Dang Yin Xuand Tianyuan XuVolume 2013 Article ID 387124 8 pages

A Green Preconcentration Method for Determination of Cobalt and Lead in Fresh Surface and WasteWater Samples Prior to Flame Atomic Absorption Spectrometry Naeemullah Tasneem Gul KaziFaheem Shah Hassan Imran Afridi Sumaira Khan Sadaf Sadia Arian and Kapil Dev BrahmanVolume 2012 Article ID 713862 8 pages

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 256956 1 pagehttpdxdoiorg1011552013256956

EditorialAnalysis and Fate of Emerging Pollutants duringWater Treatment

Fei Qi1 Guang-Guo Ying2 Kaimin Shih3 Jolanta Kumirska4

Elif Pehlivanoglu-Mantas5 and Xiaojun Luo2

1 Beijing Key Lab for Source Control Technology of Water Pollution College of Environmental Science and EngineeringBeijing Forestry University No 35 Qinghua East Road Beijing 100083 China

2 State Key Laboratory of Organic Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of SciencesGuangzhou 510640 China

3Department of Civil Engineering The University of Hong Kong Pokfulam Road Hong Kong4Department of Environmental Analysis Faculty of Chemistry University of Gdansk Sobieskiego 1819 80-952 Gdansk Poland5 Environmental Engineering Department Istanbul Technical University Ayazaga Campus Maslak 34469 Istanbul Turkey

Correspondence should be addressed to Fei Qi qifeibjfueducn

Received 23 April 2013 Accepted 23 April 2013

Copyright copy 2013 Fei Qi et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Emerging pollutants defined as compounds that are notcurrently covered by existing water-quality regulations allover the world have not been studied widely before and arethought to be potential threats to environmental ecosystemsand human health This special issue compiles 5 excitingpapers which are very meticulously performed researches

Generally emerging pollutants encompass a diversegroup of compounds including pharmaceuticals drugs ofabuse personal-care products (PCPs) steroids and hor-mones surfactants perfluorinated compounds (PFCs) flameretardants industrial additives and agents gasoline additivesnew disinfection byproducts (DBPs) nanomaterials and thetoxic minerals

The analysis methods occurrence and fate of hormonaland endocrine disruptors compounds (EDCs) were dis-cussed in two papers of this special issue R Guedes-Alonsoet al determine the hormonal residues in treated water byultrahigh performance liquid chromatography-tandem massspectrometry (UPLC-MS) and evaluate the efficiency ofthe conventional wastewater treatment for the removal ofhormonal compounds Moreover Y Liu et al study anotherkinds of PPCPs named as phthalate esters that is typicalkind of EDCs The occurrence in a surface water and theremoval efficiency in a traditional drinking water treatmentpalnt are studied According to results of the two papers

the occurrence and fate of hormonal and EDCs in water orwastewater treatment are very clear

J Xing et al report a new wastewater treatment technol-ogy bioflocculation for the removal of sulfamethoxazole thatis a typical pharmaceutical in wastewater The performanceand the reaction mechanism of the biodegradation of sul-famethoxazole by the bioflocculation are discussed in depthMoreover the optimum reaction condition is obtained

The heavy metal and toxic mineral are also importantpollutants in the environment especially in the mining areaTwo papers of this issue are focused on this K Naeemul-lah et al report a green preconcentration method for thedetermination of cobalt and lead in water Y Liu et al do anovel research on the electrochemical reaction of pyrite as asimulation of the natural environmental

By compiling this special issue we hope to enrich ourreaders and researchers on the analysis and fate of emergingpollutants during water treatment

Fei QiGuang-Guo Ying

Kaimin ShihJolanta Kumirska

Elif Pehlivanoglu-MantasXiaojun Luo

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 419349 8 pageshttpdxdoiorg1011552013419349

Research ArticleOccurrence and Removal Characteristics of Phthalate Estersfrom Typical Water Sources in Northeast China

Yu Liu Zhonglin Chen and Jimin Shen

State Key Laboratory of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Jimin Shen shenjiminhiteducn

Received 21 December 2012 Accepted 3 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Yu Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The presence of phthalate esters (PAEs) in the environment has gained a considerable attention due to their potential impactson public health This study reports the first data on the occurrence of 15 PAEs in the water near the Mopanshan Reservoirmdashthenew and important water source of Harbin city in Northeast China As drinking water is a major source for human exposureto PAEs the fate of target PAEs in the two waterworks (Mopanshan Waterworks and Seven Waterworks) was also analyzed Theresults demonstrated that the total concentrations of 15 PAEs in the water near the Mopanshan Reservoir were relatively moderateranging from 3558 to 92265 ngL with the mean value of 29431 ngL DBP and DEHP dominated the PAE concentrations whichranged from 525 to 44982 ngL and 1289 to 65709 ngL respectivelyThe occurrence and concentrations of these compoundswereheavily spatially dependent Meanwhile the results on the waterworks samples suggested no significant differences in PAE levelswith the input of the raw waters Without effective and stable removal of PAEs after the conventional drinking water treatment inthe waterworks (258 to 765) the risks posed by PAEs through drinking water ingestion were still existing which should bepaid special attention to the source control in theMopanshan Reservoir and some advanced treatment processes for drinking watersupplies

1 Introduction

Phthalate acid esters a class of chemical compounds mainlyused as plasticizers for polyvinyl chloride (PVC) or to alesser extent other resins in different industrial activities areubiquitous in the environment and have evoked interest inthe past decade due to endocrine disrupting effects and theirpotential impacts on public health [1ndash3]

Worldwide production of PAEs is approximately 6 mil-lion tons per year [4] As PAEs are not chemically boundto the polymeric matrix in soft plastics they can enter theenvironment by losses during manufacturing processes andby leaching or evaporating from final products [5]Thereforethe occurrence and fate of specific PAEs in natural waterenvironments have been observed and also there are a lot ofconsiderable controversies with respect to the safety of PAEsin water [5ndash10]

Six PAE compounds including dimethyl (DMP) diethyl(DEP) dibutyl (DBP) butylbenzyl (BBP) di(2-ethylhexyl)

(DEHP) and di-n-octyl phthalate (DNOP) are classifiedas priority pollutants by the US Environmental ProtectionAgency (EPA) Though the toxicity of PAEs to humans hasnot been well documented for some years the Ministry ofEnvironmental Protection in China has regulated phthalatesas environmental pollutants In addition the standard inChina concerning analytical controls on drinkingwaters doesnot specifically identify any PAEs as organic pollutant indexesto be determined by the new drinking water standard in 2007(Standard for drinking water quality GB5749-2006) whichwas forced to be monitored for the drinking water supplies in2012 Consequently official data about the presence of thesepollutants in the aquatic environment of some cities are notavailable

Harbin the capital of Heilongjiang Province is a typicallyold industrial base and economically developed city with apopulation of over 3million inNortheast China As the newlyenabledwater source forHarbin cityMopanshanwaterworkssupply the whole city with drinking water through long

2 Journal of Analytical Methods in Chemistry

China

HarbinMopanshan

Reservoir

LongfengshanReservoir

Figure 1 Spatial distribution of the 16 sampling sites near the Mopanshan Reservoir in Northeast China

distance transfer from the Mopanshan Reservoir To theauthorsrsquo knowledge the occurrence and fate of PAEs in thewater near this area and its relative waterworks have notpreviously been examined

The objectives of this study were (i) to determine theoccurrence of PAEs and clarify the fate and distribution ofthe pollutants in the water source (ii) to examine the twowaterworks where traditional drinking water treatment stepwas evaluated on the PAEs removal efficiencies and (iii) toevaluate the potential for adverse effects of PAEs on humanhealth Therefore the investigation of PAEs in the water canprovide a valuable record of contamination in Harbin city

2 Materials and Methods

21 Chemical Fifteen PAEs standard mixture includingdimethyl phthalate diethyl phthalate diisobutyl phthalatedi-n-butyl phthalate di(4-methyl-2-pentyl) phthalate di(2-ethoxyethyl) phthalate di-n-amyl phthalate di-n-hexylphthalate butyl benzyl phthalate di(hexyl-2-ethylhexyl)phthalate di(2-n-butoxyethyl) phthalate dicyclohexyl phthal-ate di(2-ethylhexyl) phthalate di-n-nonyl phthalate di-n-octylphthalate at 1000 120583gmL each and surrogate standardsconsisting of diisophenyl phthalate di-n-phenyl phthal-ate and di-n-benzyl phthalate in a mixture solution of500120583gmL each were supplied by AccuStandard Inc Asthe internal standard benzyl benzoate was also purchasedfrom AccuStandard Inc All solvents (acetone hexane anddichloromethane) used were HPLC-grade and were pur-chased from J T Baker Co (USA) Anhydrous sodiumsulfate (Tianjin Chengguang Chemical Reagent Co China)was cleaned at 600∘C for 6 h and then kept in a desiccatorbefore use

22 Sample Collection and Preparation Harbin the capitalof Heilongjiang province in China imports nearly all of itsdrinking water from two sources the Mopanshan Reservoir

Raw water Coagulation sedimentation Filtration Tank

Sampling site Sampling site

Figure 2 Schematic diagram of the waterworks

(long-distance transport project) and the Songhua River (oldwater source)

Water samples from the Mopanshan Reservoir andMopanshan waterwork were collected in 2008 The locationsof the sampling sites near the Mopanshan Reservoir are pre-sented in Figure 1 as a comparison sampling from anotherHarbin water supplymdashSeven waterworks with water sourcefrom the SonghuaRiverwas performed in 2011 In eachwater-works with considering the hydraulic retention time threesets of raw water samples (influent) were taken and thenthe final finished waters (effluent) after the whole treatmentprocess were carried out for the collectionsThe flow diagramof the waterworks is shown in Figure 2

Samples were collected using 20 L glass jars from 05mbelow the water surface During the whole sampling processthe global position system was used to locate the samplingstations (details in Table 1) All samples were transferred tothe laboratory directly after sampling and stored at 4∘C priorto extraction within 2 d

Water samples were filtered under vacuum through glassfiber filters (07 120583mpore sizes) Prior to extraction each sam-ple was spiked with surrogate standards The water sampleswere extracted based on a classical liquid phase extractionmethod (USEPA method 8061) with slight modificationsBriefly 1 L of water samples was placed in a separating funneland extracted by means of mechanical shaking with 150mLdichloromethane and then with filtration on sodium sulfate(about 20 g) the organic extracts were concentrated usinga rotary evaporator The exchange of solvent was done byreplacing dichloromethane with hexane Finally they were

Journal of Analytical Methods in Chemistry 3

Table 1 Detailed descriptions of the sampling locations

Number Sampling site Name Latitude Longitude1 Lalin Jinsan Bridge Mangniu River E127∘0210158405310158401015840 N45∘510158404510158401015840

2 Xingsheng Town Gaojiatun Lalin River E127∘0610158401110158401015840 N44∘5110158405710158401015840

3 Dujia Town Shuguang Lalin River E127∘1010158404410158401015840 N44∘4810158404110158401015840

4 Shanhe Town Taipingchuan Lalin River E127∘1810158403610158401015840 N44∘4310158405010158401015840

5 Xiaoyang Town Qichuankou Lalin River E127∘2310158405410158401015840 N44∘3910158404610158401015840

6 Shahezi Town Mopanshan Reservoir E127∘3810158405910158401015840 N44∘2410158401710158401015840

7 Shahezi Town Gali Lalin River E127∘3510158401710158401015840 N44∘3110158405610158401015840

8 Chonghe Town Changcuizi Mangniu River E127∘4610158403610158401015840 N44∘3510158404610158401015840

9 Chonghe Town Xingguo Mangniu River E127∘3510158401710158401015840 N44∘3110158405710158401015840

10 Longfeng Town Mangniu River E127∘3510158401910158401015840 N44∘4310158404810158401015840

11 Changpu Town Zhonghua Mangniu River E127∘1610158403010158401015840 N45∘110158404210158401015840

12 Erhe Town Shuanghe Mangniu River E127∘1810158403210158401015840 N45∘410158402810158401015840

13 Zhiguang Town Songjiajie Mangniu River E127∘341015840310158401015840 N45∘110158402010158401015840

14 Zhiguang Town Wuxing Mangniu River E127∘2910158402010158401015840 N45∘010158404310158401015840

15 Changpu Town Xingzhuang Mangniu River E127∘1010158404210158401015840 N45∘410158403610158401015840

16 Yingchang Town Xingguang Lalin River E126∘551015840810158401015840 N45∘91015840010158401015840

reduced to 05mL under gentle nitrogen flow The internalstandard was added to the sample prior to instrumentalanalysis

23 Chemical Analysis The extracted compounds weredetermined by gas chromatography coupled to mass spec-trometer analysis as described in other publications [1112] Briefly extracted samples were injected into an Agilent6890 Series GC equipped with a DB-35MS capillary column(Agilent 30m times 025mm id 025120583m film thickness) andan Agilent 5973 MS detector operating in the selective ionmonitoring mode The column temperature was initially setat 70∘C for 1min then ramped at 10∘Cmin to 300∘C andheld constant for 10min The transfer line and the ion sourcetemperature were maintained at 280 and 250∘C respectivelyHelium was used as the carrier gas at a flow rate of 1mLminThe extracts (20 120583L) were injected in splitless mode with aninlet temperature of 300∘C

24 Quality Assurance and Quality Control All glasswarewas properly cleaned with acetone and dichloromethanebefore use Laboratory reagent and instrumental blanks wereanalyzed with each batch of samples to check for possiblecontamination and interferences Only small levels of PAEswere found in procedural blanks in some batches andthe background subtraction was appropriately performed inthe quantification of concentration in the water samplesCalibration curves were obtained from at least 3 replicateanalyses of each standard solution The surrogate standardswere added to all the samples to monitor matrix effectsRecoveries of PAEs ranged from 62 to 112 in the spikedwater and the surrogate recoveries were 751 plusmn 127 fordiisophenyl phthalate 723 plusmn 143 for di-n-phenyl phtha-late and 1026 plusmn 104 for di-n-benzyl phthalate in thewater samples The determination limits ranged from 6 to30 ngL A midpoint calibration check standard was injected

as a check for instrumental drift in sensitivity after every10 samples and a pure solvent (methanol) was injected as acheck for carryover of PAEs from sample to sample All theconcentrations were not corrected for the recoveries of thesurrogate standards

3 Results and Discussion

31 PAEs in Water Source The PAEs in the waters fromthe sampling sites near the Mopanshan Reservoir wereinvestigated and the results are presented in Table 2 Thesum15

PAEs concentrations ranged from 3558 to 92265 ngLwith the geometric mean value of 29431 ngL Among the15 PAEs detected in the waters DIBP DBP and DEHP weremeasured in all the samples with the average concentrationsbeing 1966 8014 and 17741 ngL respectively The threePAE congeners are important and popular addictives inmany industrial products including flexible PVC materialsand household products suggesting the main source of PAEcontaminants in the water [13] The correlations of the con-centration of DEHP DBP and DIBP with the concentrationsof total PAEs in the water samples are shown in Figure 3and a relatively significant correlation between sum

15

PAEs andDEHP concentration was found suggesting the importantpart played by DEHP in total concentrations of PAEs inthe water bodies near the Mopanshan Reservoir In otherwords the contribution of DEHP to total PAEs was higherthan that of other PAE congeners in the water samples Inaddition DMP DEP and DNOP with the mean value of140 284 and 541 ngL respectively only detected at somesampling sites and have also attracted much attention asthe priority pollutants by the China National EnvironmentalMonitoring Center On the contrary the concentrations of6 PAEs (DMEP BMPP BBP DBEP DCHP and DNP) werebelow detection limits in all the water samples near theMopanshan Reservoir which is easily explained in terms ofmuch lower quantities of present use in China

4 Journal of Analytical Methods in Chemistry

0 2000 4000 6000 80000

2000

4000

6000

Con

cent

ratio

ns (n

gL)

DEHP

119903 = 0885 119875 lt 001

sum15PAEs (ngL)

(a)

0 2000 4000 6000 80000

2000

4000

Con

cent

ratio

ns (n

gL)

sum15PAEs (ngL)

DBP

119903 = 0812 119875 lt 001

(b)

1000

500

0

0 2000 4000 6000 8000sum15PAEs (ngL)

DIBP

Con

cent

ratio

ns (n

gL)

119903 = 0724 119875 lt 001

(c)

Figure 3 Correlations of the concentration of the major PAEs (DEHP DBP and DIBP) with the concentrations of total PAEs in the watersamples

Table 2 Concentrations of 15 PAEs in water samples near the Mopanshan Reservoir

PAEs Abbreviation Water (ngL)Range Mean Frequency

Dimethyl phthalate DMP ndndash424 140 816Diethyl phthalate DEP ndndash550 284 1516Diisobutyl phthalate DIBP 400ndash6588 1966 1616Dibutyl phthalate DBP 525ndash44982 8014 1616bis(2-methoxyethyl)phthalate DMEP nd nd 016bis(4-methyl-2-pentyl)phthalate BMPP nd nd 016bis(2-ethoxyethyl)phthalate DEEP ndndash546 128 516Dipentyl phthalate DPP ndndash925 455 1016Dihexyl phthalate DHXP ndndash651 162 516Benzyl butyl phthalate BBP nd nd 016bis(2-n-butoxyethyl)phthalate DBEP nd nd 016Dicyclohexyl phthalate DCHP nd nd 016bis(2-ethylhexyl)phthalate DEHP 1289ndash65709 17741 1616Di-n-octyl phthalate DNOP ndndash4482 541 516Dinonyl phthalate DNP nd nd 016sum15

PAEs 3558ndash92265 29431 mdash

The distribution of 15 PAEs (sum15

PAEs) studied and6 US EPA priority PAEs (sum

6

PAEs including DMP DEPDIBP DBP DEHP and DNOP) in the waters from differentsampling sites are shown in Figure 4 There was an obviousvariation in the total sum

15

PAEs concentrations in water sam-ples near the Mopanshan Reservoir the concentrations ofsum6

PAEs from the same sampling sites varied from 2690 to90860 ngL with an average of 28686 ngL the distributionspectra of which observed for all the sampling sites weresimilar tosum

15

PAEsThe highest levels of PAEs contaminationwere seen on the sampling site 3 followed by some relativelyheavily polluted sites (site 16 13 9 10 and 11) indicating thatthese sites served as important PAE sources and the spatialdistribution of PAEs was site specific The levels in the watersexamined varied over a wide range especially in theMangniu

River near theMopanshan Reservoir (in some case overmorethan one order of magnitude) In general it should be notedthat there might be a relation of PAEs levels with the input oflocal waste such as sewage water food packaging and scrapmaterial near the sampling point which were found duringthe sampling period

32 PAE Congener Profiles in the Water Different PAE pat-terns may indicate different sources of PAEs Measurementof the individual PAE composition is helpful to track thecontaminant source and demonstrate the transport and fateof these compounds in water [11] The relative contributionsof the 9 detectable PAE congeners to thesum

15

PAEs concentra-tions in the water are presented in Figure 5 It is clear thatDEHP was the most abundant in the water samples with

Journal of Analytical Methods in Chemistry 5

0

500

1000

1500

4000

6000

8000

10000

Con

cent

ratio

ns (n

gL)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

sum15PAEssum6PAEs

Figure 4 Spatial distributions of the 16 sampling sites near theMopanshan Reservoir

the exception of site 2 3 and 11 contributions ranging from331 to 963 followed byDBP ranging from 21 to 363The results are consistent with the above data for overallanalysis that DBP and DEHP are the dominant componentsof the PAEs distribution pattern in each sampling site whichreflected the different pattern of plastic contaminant inputduring the sampling period Similarly DIBP and DBP areused in epoxy resins or special adhesive formulations withthe different proportions of these two PAE congeners whichwere also the important indicator of the information pollutedby PAEs for the sampling locations Although the limitedsample number draws only limited conclusions there is stillreason to note that a leaching from the plastic materials intothe runoff water is possible and that water runoff from thecontaminated water is a burden pathway from differentsources of PAEs [14]

33 Comparison with Other Water Bodies Comparison withthe total PAEs concentrations is nevertheless very limited dueto the different analysis compounds However the individualPAE namely DBP and DEHP is by far the most abundantin other researches and it is possible to make a camparisonwith our findings In this case the results of DBP and DEHPconcentrations published in literatures for kinds of waterbodies are presented together in Table 3

The DEHP and DBP concentrations of the present studyshowed to some extent lower concentration levels than thosereported in the other water bodies in China In comparisonthe results were comparable or similar to those from theexaminations described in other foreign countries For exam-ple as shown in Table 3 the DEHP concentrations were sim-ilar to the surface waters from the Netherlands and Italydescribed in the literature Meanwhile these concentrationsin this study were quite lower than the Yangtze River andSecond Songhua River in China

0

20

40

60

80

100

DEEP DPP DHXP DEHP DNOP DBP

DIBP DEP DMP

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

Com

posit

ion

()

Figure 5 PAE composition of thewater samples in 16 sampling sites

In conclusion as compared to the results of other studiesthe waters near the Mopanshan Reservoir were moderatelypolluted by PAEs Therefore there is a definite need to set upa properly planned and systematic approach to water controlnear the Mopanshan Reservoir

34 PAE Levels in the Waterworks The Mopanshan Water-works (MPSW) equipped essentially with the water sourceof the Mopanshan Reservoir has been investigated in orderto assess the fate of the PAEs during the drinking watertreatment process For comparison a sampling campaign forthe determination of PAEs levels in the Seven Waterworks(SW waterworks with the old water source of the SonghuaRiver) was carried out Both waterworks operate coagulationsedimentation and followed by filtration treatment processwhich are typical traditional drinking water treatment

The measured concentrations in the raw and finishedwater of the two investigated waterworks are shown inFigure 6 Six out of fifteen PAEs were detected in the fin-ished water from the two waterworks The detected PAEswere DMP DEP DIBP DBP DEHP and DNOP and theother investigated phthalates are of minor importance withconcentrations all below the limit of detection As showin Figure 6 the measured concentrations of the analyzedPAEs in the finished water of the two waterworks variedstronglyThemost important compound in the finishedwaterwas DEHP with the mean concentration of 34737 and40592 ngL for the MPSW and SW respectively suggestingthe highest relative composition of total PAE concentrationsin the drinking water

For the raw water from the different water sources DMPand DIBP concentrations in the MPSW were much lowerthan the ones in the SW and the concentrations of DEPDBP DEHP andDEHPwere relatively comparable in the two

6 Journal of Analytical Methods in Chemistry

Table 3 Comparison of the concentrations of DEHP and DBP in the water bodies (ngL)

Location DEHP DBP ReferenceRange Median Mean Range Median Mean

Surface water Germany 330ndash97800 2270 mdash 120ndash8800 500 mdash [14]Surface water the Netherlands ndndash5000 320 mdash 66ndash3100 250 mdash [15]Seine River estuary France 160ndash314 mdash mdash 67ndash319 mdash mdash [16]Tama River Japan 13ndash3600 mdash mdash 8ndash540 mdash mdash [17]Velino River Italy ndndash6400 mdash mdash ndndash44300 mdash mdash [2]Surface water Taiwan ndndash18500 mdash 9300 1000ndash13500 mdash 4900 [18]Surface water Jiangsu China 556ndash156707 mdash mdash 16ndash58575 mdash mdash [19]Yangtze River mainstream China 3900ndash54730 mdash mdash ndndash35650 mdash mdash [20]Middle and lower Yellow River China 347ndash31800 mdash mdash ndndash26000 mdash mdash [21]Second Songhua River China ndndash1752650 370020 mdash ndndash5616800 mdash 717240 [22]Urban lakes Guangzhou China 87ndash630 170 240 940ndash3600 1990 2030 [11]Xiangjiang River China 620ndash15230 mdash mdash mdash mdash mdash [23]This study 1289ndash65709 6710 17741 525ndash44982 1103 8014

0

500

1000

100001200014000

0

20

40

60

80

100

Raw waterFinished waterRemoval

Rem

oval

()

Con

cent

ratio

ns (n

gL)

DMP DEP DIBP DBP DEHP DNOP

(a)

Raw waterFinished waterRemoval

0

500

1000

1500

2000

100001200014000

0

20

40

60

80

100C

once

ntra

tions

(ng

L)

Rem

oval

()

DMP DEP DIBP DBP DEHP DNOP

(b)

Figure 6 PAEs detected in the water samples from the MPSW (a) and SW (b)

waterworks The removal of PAEs by these two waterworksranged from 258 to 765 which varied significantly with-out stable removal efficienciesThe lower removal efficienciesfor DMP and DNOP were observed in the SW with theremoval less than 30 For both the waterworks no soundremoval efficiencies were obtained for the PAEs indicatingthat the traditional drinking water treatment cannot showgood performance to eliminate these micro pollutants whichhas nothing to do with the type of the water source

Traditional drinking water treatment focuses on dealingwith the particles and colloids in terms of physical processesMany studies of the environmental fates of PAEs have demon-strated that oxidation or microbial action is the principalmechanism for their removal in the aquatic systems [24ndash26]Therefore the treatment process should be the combinationswith the key techniques for removing PAEs from the waterOn the other hand since the removal efficiencies of PAEs by

these advance drinking water treatments in waterworks hasnot been systematically studied to date further research inthis direction would seem to be required

35 Exposure Assessment of PAEs in Water To evaluate thepotential and adverse effects of PAEs quality guidelines forsurface water and drinking water standard were used Theresults indicated that the mean concentrations of DBP andDEHP at levels were well below the reference doses (RfD)regarded as unsafe by the EPA for the surface water Thelevels were not also above the RfD recommended by China(Environmental Quality Standard for SurfaceWater of ChinaGB3838-2002) On the other hand the amounts of DEHPpresent in public water supplies should be lower than thedrinkingwater standard (0006mgL for EPA and 0008mgLfor China) According to the results the concentrations of

Journal of Analytical Methods in Chemistry 7

DEHP in drinkingwater samples from theMPSWwere lowerthan the limited value

PAEs are also considered to be endocrine disruptingchemicals (EDCs) whose effects may not appear until long-term exposure According to the results PAEs were detectedin the drinking water constantly ingested in daily life indi-cating that drinking water is an important source of humanexposure to PAEs contaminants Assuming a daily waterconsumption rate of 2 L and an average body weight of 60 kgfor adults the average daily intake of DEHP DBP and DIBPby way of drinking water from MPSW was calculated to be1158 1352 and 81 ngkgd respectively In comparison thevalues of SW with the water source of the Songhua Riverwere relatively higher with the calculated results of 1353140 and 155 ngkgd for DEHP DBP and DIBP respectivelyIn this study the estimated daily intake levels of DEHPfrom the drinking water were quite lower than the RfDof 20000 ngkgd released by the EPA However some ofPAEs are partly metabolised in the organism and futureexperiments should be focused on determining the potentialeffects of the metabolites [27]

Currently treated water from the Songhua River is fornonpotable uses and MPSW is the exclusive waterworks runfor the water supply of Harbin city However populationgrowth and drought cycle are limited by the availability of rawwater from theMopanshan Reservoir Tomeet the increasingdemand local and regional water authorities have begun acampaign of second water supply project from the SonghuaRiver again which needs the protection of the Songhua Riverand advanced water treatment for the source

4 Conclusions

This study provided the first detailed data on the contami-nation status of 15 PAEs in the water near the MopanshanReservoir The concentration range of 15 PAEs in the sampleswas from 3558 to 92265 ngL with the mean value of29431 ngL DEHP andDBPwere themain pollutants among15 PAEs accounting for the main watershed pollution Theoccurrence and distribution of PAEs from different samplingsites in the water source varied largely suggesting that thespatial distribution of PAEs was site specific In additionthe monitoring of PAEs in the waterworks also showed thatPAEs can be detected in the drinking water and certaintoxicological risks to drinking water consumers were foundThese results reported here contribute to an understandingof how PAE contaminants are distributed in the new watersource and the waterworks in Harbin city as well as forminga basis for further modeling risk assessment and selection ofdrinking water treatment technology

In conclusion the results implied that no urgent reme-diation measures were required with respect to PAEs in thewaters However the ecological and health effects of thesesubstances through drinkingwater at the relatively lower con-centrations still need further notice in light of their possiblebiological magnifications Therefore the long-term sourcecontrol in the water and adding advanced treatment processfor drinking water supplies should be given special attentionin this area

Acknowledgments

This work was supported by the National Natural ScienceFoundation of China (1077029) the Funds for CreativeResearch Groups of China (Grant no 51121062) the NationalNatural Science Foundation of China (51078105) and theOpen Project of the State Key Laboratory of Urban WaterResource and Environment Harbin Institute of Technology(no QA201019)

References

[1] M Nikonorow H Mazur and H Piekacz ldquoEffect of orallyadministered plasticizers and polyvinyl chloride stabilizers inthe ratrdquo Toxicology and Applied Pharmacology vol 26 no 2 pp253ndash259 1973

[2] M Vitali M Guidotti G Macilenti and C Cremisini ldquoPhtha-late esters in freshwaters asmarkers of contamination sourcesmdasha site study in ItalyrdquoEnvironment International vol 23 no 3 pp337ndash347 1997

[3] G Latini C de Felice G Presta et al ldquoIn utero exposure todi-(2-ethylhexyl)phthalate and duration of human pregnancyrdquoEnvironmental Health Perspectives vol 111 no 14 pp 1783ndash17852003

[4] C E Mackintosh J A Maldonado M G Ikonomou and F AP C Gobas ldquoSorption of phthalate esters and PCBs in a marineecosystemrdquo Environmental Science and Technology vol 40 no11 pp 3481ndash3488 2006

[5] M Clara G Windhofer W Hartl et al ldquoOccurrence of phtha-lates in surface runoff untreated and treated wastewater andfate during wastewater treatmentrdquo Chemosphere vol 78 no 9pp 1078ndash1084 2010

[6] M M Abdel Daiem J Rivera-Utrilla R Ocampo-Perez J DMendez-Dıaz andM Sanchez-Polo ldquoEnvironmental impact ofphthalic acid esters and their removal fromwater and sedimentsby different technologiesmdasha reviewrdquo Journal of EnvironmentalManagement vol 109 pp 164ndash178 2012

[7] L Chen Y Zhao L Li B Chen and Y Zhang ldquoExposureassessment of phthalates in non-occupational populations inChinardquo Science of the Total Environment vol 427-428 pp 60ndash69 2012

[8] M J Teil M Blanchard andM Chevreuil ldquoAtmospheric fate ofphthalate esters in an urban area (Paris-France)rdquo Science of theTotal Environment vol 354 no 2-3 pp 212ndash223 2006

[9] P Roslev K Vorkamp J Aarup K Frederiksen and P HNielsen ldquoDegradation of phthalate esters in an activated sludgewastewater treatment plantrdquo Water Research vol 41 no 5 pp969ndash976 2007

[10] J Gasperi S Garnaud V Rocher and R Moilleron ldquoPrioritypollutants in wastewater and combined sewer overflowrdquo Scienceof the Total Environment vol 407 no 1 pp 263ndash272 2008

[11] F Zeng K Cui Z Xie et al ldquoOccurrence of phthalate estersin water and sediment of urban lakes in a subtropical cityGuangzhou South Chinardquo Environment International vol 34no 3 pp 372ndash380 2008

[12] F Zeng K Cui Z Xie et al ldquoPhthalate esters (PAEs) emergingorganic contaminants in agricultural soils in peri-urban areasaround Guangzhou Chinardquo Environmental Pollution vol 156no 2 pp 425ndash434 2008

[13] G Wildbrett ldquoDiffusion of phthalic acid esters from PVC milktubingrdquo Environmental Health Perspectives vol 3 pp 29ndash351973

8 Journal of Analytical Methods in Chemistry

[14] H Fromme T Kuchler T Otto K Pilz J Muller and AWenzel ldquoOccurrence of phthalates and bisphenol A and F inthe environmentrdquoWater Research vol 36 no 6 pp 1429ndash14382002

[15] A D Vethaak J Lahr S M Schrap et al ldquoAn integrated assess-ment of estrogenic contamination and biological effects in theaquatic environment ofTheNetherlandsrdquoChemosphere vol 59no 4 pp 511ndash524 2005

[16] C Dargnat M Blanchard M Chevreuil andM J Teil ldquoOccur-rence of phthalate esters in the Seine River estuary (France)rdquoHydrological Processes vol 23 no 8 pp 1192ndash1201 2009

[17] T Suzuki K Yaguchi S Suzuki and T Suga ldquoMonitoring ofphthalic acid monoesters in river water by solid-phase extrac-tion and GC-MS determinationrdquo Environmental Science andTechnology vol 35 no 18 pp 3757ndash3763 2001

[18] S Y Yuan C Liu C S Liao and B V Chang ldquoOccurrenceand microbial degradation of phthalate esters in Taiwan riversedimentsrdquo Chemosphere vol 49 no 10 pp 1295ndash1299 2002

[19] B Li C Qu and J Bi ldquoIdentification of trace organic pollutantsin drinking water and the associated human health risks inJiangsu Province Chinardquo Bulletin of Environmental Contami-nation and Toxicology pp 1ndash5 2012

[20] F Wang X Xia and Y Sha ldquoDistribution of phthalic acidesters in Wuhan section of the Yangtze River Chinardquo Journalof Hazardous Materials vol 154 no 1ndash3 pp 317ndash324 2008

[21] Y J Sha X H Xia and X Q Xiao ldquoDistribution characters ofphthalic acid ester in the waters middle and lower reaches ofthe Yellow Riverrdquo China Environmental Science vol 26 no 1pp 120ndash124 2006

[22] J Lu L-B Hao C-Z Wang W Li R-J Bai and D YanldquoDistribution characteristics of phthalic acid esters in middleand lower reaches of no 2 Songhua Riverrdquo EnvironmentalScience amp Technology vol 12 article 014 2007

[23] X J Zhu and Y Y Qiu ldquoMeasuring the phthalates of xiangjiangriver using liquid-liquid extraction gas chromatographyrdquoAdvanced Materials Research vol 301 pp 752ndash755 2011

[24] B L Yuan X Z Li and N Graham ldquoAqueous oxida-tion of dimethyl phthalate in a Fe(VI)-TiO

2

-UV reaction sys-temrdquoWater Research vol 42 no 6-7 pp 1413ndash1420 2008

[25] Z Yunrui ZWanpeng L FudongW Jianbing and Y ShaoxialdquoCatalytic activity of RuAl2O3 for ozonation of dimethylphthalate in aqueous solutionrdquo Chemosphere vol 66 no 1 pp145ndash150 2007

[26] H N Gavala U Yenal and B K Ahring ldquoThermal andenzymatic pretreatment of sludge containing phthalate estersprior tomesophilic anaerobic digestionrdquoBiotechnology and Bio-engineering vol 85 no 5 pp 561ndash567 2004

[27] Y Guo Q Wu and K Kannan ldquoPhthalate metabolites in urinefrom China and implications for human exposuresrdquo Environ-ment International vol 37 no 5 pp 893ndash898 2011

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 210653 8 pageshttpdxdoiorg1011552013210653

Research ArticleSimultaneous Determination of Hormonal Residuesin Treated Waters Using Ultrahigh Performance LiquidChromatography-Tandem Mass Spectrometry

Rayco Guedes-Alonso Zoraida Sosa-Ferrera and Joseacute Juan Santana-Rodriacuteguez

Departamento de Quımica Universidad de Las Palmas de Gran Canaria 35017 Las Palmas de Gran Canaria Spain

Correspondence should be addressed to Jose Juan Santana-Rodrıguez jsantanadquiulpgces

Received 28 December 2012 Accepted 7 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Rayco Guedes-Alonso et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

In the last years hormone consumption has increased exponentially Because of that hormone compounds are considered emergingpollutants since several studies have determinted their presence in water influents and effluents of wastewater treatment plants(WWTPs) In this study a quantitative method for the simultaneous determination of oestrogens (estrone 17120573-estradiol estriol17120572-ethinylestradiol and diethylstilbestrol) androgens (testosterone) and progestogens (norgestrel andmegestrol acetate) has beendeveloped to determine these compounds in wastewater samples Due to the very low concentrations of target compounds in theenvironment a solid phase extraction procedure has been optimized and developed to extract and preconcentrate the analytesDetermination and quantification were performed by ultrahigh performance liquid chromatography-tandem mass spectrometry(UHPLC-MSMS) The method developed presents satisfactory limits of detection (between 015 and 935 ngsdotLminus1) good recoveries(between 73 and 90 for the most of compounds) and low relative standard deviations (under 84) Samples from influents andeffluents of two wastewater treatment plants of Gran Canaria (Spain) were analyzed using the proposed method finding severalhormones with concentrations ranged from 5 to 300 ngsdotLminus1

1 Introduction

In general it is supposed that more than 100000 differentchemical compounds can be introduced in the Environmentmany of them in very small quantity However a lot of thesecompounds are not included as pollutants in the legislationAlthough these compounds named emerging pollutants arenot regulated as pollutants they probably will be in the futurebecause of their potential negative effect in the ecosystem For20 years many articles have reported the presence of theseldquonew compoundsrdquo in wastewater [1 2]

The emerging pollutant origin is mainly anthropogenicconsidering that the majority of these compounds are bio-logically active substances that are synthesized to use themin agriculture industry and medicine The main source ofthese emerging pollutants is the residual urbanwaters and thewastewater treatment plants effluents because many of these

WWTPs are not designed or optimized to treat this kind ofcompounds [3]

Hormones are one of the most potent endocrine disrupt-ing compounds as well as are considered also as emergingpollutants Hormones can be differentiated in oestrogensandrogens and progestogens Some of them have limits intheir use but not a specific legislation [4]

The main characteristic of these pollutants is that it isnot necessary to remain in the environment to cause negativeeffects in view of the fact that their constant introduction init offsets their removal or degradation [5]

The steroid hormones help controlling the metabolisminflammations immunological functions water and salt bal-ance sexual development and the capacity of withstandingillnesses [6] The term steroid can be used for naturalhormones produced by the body as well as for artificiallyproduced medicines that increase the natural steroid effect

2 Journal of Analytical Methods in Chemistry

In the last 50 years the natural and synthetic hormoneworldwide consumption has grown as much as in humanmedicine as in cattle farming and they become the mostprescribed medicines [7]

A significant quantity of consumed oestrogens leaves theorganism through excretions For example 17120573-estradiol (E2)is oxidized rapidly becoming an estrone (E1) that can turninto estriol afterwards (E3) Besides the 17120572-ethinyl estradiol(EE) is excreted as conjugated [8]

With regard to emission sources in the first place arethe wastewater treatment plants (WWTPs) [9] and secon-darily cattle waste such as those leachates from dung anduncontrolled dumping [10] Several studies made in theWWTPs have reported that the treatment plants are capableof eliminating around 60 of hormones [11ndash13]

The identification of hormone residues in environmentis of special interest because knowledge of these compoundsis a requirement to take measures in order to regulate andminimize their environmental impact

However measurement of hormone residues is a verydifficult task not only due to the difficulty in measuringvery low concentration but also due to a very complexityof the samples Therefore use of mass spectrometer (MS)as detector coupled with chromatography techniques hasbecome a powerful method for the analysis of these typesof compounds at trace levels [14ndash17] Consequently LC-MSMS is the principally chosen technique One of the mainadvantages of LC-MSMS is its ability to analyze hormoneswithout derivatization (necessary in GC) or the need ofhydrolyze the conjugated form

Due to low level concentration of these compounds inenvironmental water it is necessary to apply an extractionand preconcentration method prior to LC analysis The mostused technique of extraction and preconcentration methodfor liquid samples is the solid phase extraction (SPE) [18ndash20]

The objective of this study is to develop a rapid and simpleprocedure of extraction preconcentration and determina-tion of four steroid oestrogens (estrone (E1) 17120573-estradiol(E2) estriol (E3) and 17120572-ethinylestradiol (EE)) one non-steroidal oestrogen the diethylstilbestrol (DES) one andro-gen the testosterone (TES) and two synthetic progestogensnorgestrel (NOR) and megestrol acetate (MGA) (Table 1)based on solid phase extraction and ultrahigh performanceliquid chromatography-tandem mass spectrometry (SPE-UHPLC-MSMS) The developed method was applied tothe identification and quantification of these compoundsin wastewater samples obtained from the influents andeffluents of two wastewater treatment plants (WWTPs) ofGran Canaria (Spain) They presented different methodsof wastewater treatments WWTP 1 presented a traditionalmethod based on activated sludge while WWTP 2 used amembrane bioreactor technique

2 Materials and Methods

21 Reagents All of the hormonal compounds usedwere pur-chased from Sigma-Aldrich (Madrid Spain) Stock solutionscontaining 1000mgsdotLminus1 of each analyte were prepared by

dissolving the compound inmethanol and the solutionswerestored in glass-stoppered bottles at 4∘C prior to use Workingaqueous standard solutions were prepared daily Ultrapurewater was provided by a Milli-Q system (Millipore BedfordMA USA) HPLC-grade methanol LC-MS methanol andLC-MS water as well as the ammonia and the ammoniumacetate used to adjust the pH of the mobile phases wereobtained from Panreac Quımica (Barcelona Spain)

22 Sample Collection Water samples were collected fromthe effluents of twowastewater treatment plants located in thenorthern area of Gran Canaria in May and August of 2012WWTP 1 used a conventional activated sludge treatmentsystem while WWTP 2 employed a membrane bioreactortreatment system The samples were collected in 2 L amberglass bottles that were rinsed beforehand with methanol andultrapurewater Samples were purified through filtrationwithfibreglass filters and then with 065 120583m membrane filters(Millipore Ireland) The samples were stored in the dark at4∘C and extracted within 48 hours

23 Instrumentation For the SPE optimization the instru-ment used was an ultrahigh performance liquid chromatog-raphy with fluorescence detector (UHPLC-FD) system con-sisting of an ACQUITYQuaternary Solvent Manager (QSM)used to load samples and wash and recondition the analyticalcolumn an autosampler a column manager and a fluores-cence detector with excitation and emission wavelengths of280 and 310 nm respectively all fromWaters (Madrid Spain)

The analysis of wastewater samples was performed ina UHPLC-MSMS system from Waters (Madrid Spain)similar to the described above with a 2777 autosamplerequipped with a 25120583L syringe and a tray to hold 2mLvials and an ACQUITY tandem triple quadrupole (TQD)mass spectrometer with an electrospray ionization (ESI)interface All Waters components (Madrid Spain) werecontrolled using the MassLynx Mass Spectrometry SoftwareElectrospray ionisation parameters were fixed as followsthe capillary voltage was 3 kV in positive mode and minus2 kVin negative mode the source temperature was 150∘C thedesolvation temperature was 500∘C and the desolvation gasflow rate was 1000 Lhr Nitrogen was used as the desolvationgas and argon was employed as the collision gas

The detailed MSMS detection parameters for each hor-monal compound are presented in Table 2 and were opti-mised by the direct injection of a 1mgsdotLminus1 standard solutionof each analyte into the detector at a flow rate of 10 120583Lsdotminminus1

24 Chromatographic Conditions For the SPE optimizationthe analytical column was a 50mm times 21mm ACQUITYUHPLCBEHWaters C

18columnwith a particle size of 17120583m

(Waters Chromatography Barcelona Spain) operating at atemperature of 30∘C Analytes separation was carried outemploying the following gradient starting at 55 45 (vv)water methanol for 1 minute During 3 minutes it changedto 50 50 (vv) and stayed for 25 minutes more Finally cameback to initial conditions in 1 minute and stayed for 15

Journal of Analytical Methods in Chemistry 3

Table 1 List of hormonal compounds pKa values chemical structure and retention times

Compound pKa [21] Structure 119905119877

(min)

E3 Estriol 103

HO

OH

OH

H H

H096

E2 17120573-estradiol 103

HO

OH

H H

H218

EE 17120572-ethinylestradiol 103

HO

HO

H H

H223

E1 Estrone 103

HO

O

H

H H220

DES Diethylstilbestrol 102

HO

OH

235

TES Testosterone 151

OH

OH H

H240

MGA Megestrol acetate

O

O

O

OH

H

H306

NOR Levonorgestrel 131

OH

O

H

H

H

H263

minutes Therefore the analysis took 9 minutes at a flow of05mLsdotminminus1

For the analysis of real samples aUHPLC-MSMS systemwas used The analytical column was the same and themobile phase was water and methanol adjusted with a bufferconsisting in 01 vv ammonia and 15mM of ammoniumacetate The analysis was performed in gradient mode at aflow rate of 03mLsdotminminus1The gradient started at 50 50 (vv)mixture of water methanol which changed to 25 75 (vv) in3 minutes and returned to 50 50 in 1 minute more Finallythe gradient stayed calibrating for another 15 minutes moreThe sample volume injected was 5120583L

3 Results and Discussion

31 Optimization of Solid-Phase Extraction (SPE) There area number of parameters that affect SPE procedure such as

type of sorbent pH ionic strength sample and desorptionvolumes and wash step To optimize these parameters itused Milli-Q water spiked with a solution of fluorescenceoestrogens (estriol 17120573-estradiol and 17120572-ethinylestradiol)to obtain a final concentration of 250120583gsdotLminus1

The first parameter to optimize is the choice of sorbentsince it controls the selectivity affinity and capacity overanalytes In this study the SPE cartridges used were OASISHLB SepPak C

18(both from Waters Madrid Spain) and

BondElut ENV (fromAgilent Madrid Spain) Keeping otherparameters fixed (ionic strength of 0 sample volume of100mL) the cartridges were studied at three different pHs(5 8 and 11) From the results obtained it can be observedthat the better signals are found for SepPak C

18cartridge

(Figure 1)After choosing the optimum cartridge we used an initial

experimental design of 23 to study the influence of pH ionic

4 Journal of Analytical Methods in Chemistry

Table 2 Mass spectrometer parameters for the determination of target analytes

Compound Precursor ion(mz)

Capillary voltage(Ion mode)

Quantification ionmz(collision potential V)

Quantification ionmz(collision potential V)

E3 2872 minus65V (ESI minus) 1710 (37) 1452 (39)E2 2712 minus65V (ESI minus) 1451 (40) 1831 (31)EE 2952 minus60V (ESI minus) 1450 (37) 1589 (33)E1 2692 minus65V (ESI minus) 1450 (36) 1430 (48)DES 2671 minus50V (ESI minus) 2371 (29) 2511 (25)TES 2892 38V (ESI +) 1870 (18) 1040 (21)MGA 3855 30V (ESI +) 2673 (15) 2242 (30)NOR 3132 38V (ESI +) 1090 (26) 2451 (18)

0

500

1000

1500

2000

2500

E3 E2 EE

Peak

area

Cartridge optimizationOASIS HLB pH = 5

OASIS HLB pH = 8

OASIS HLB pH = 11SepPak C18 pH = 5

SepPak C18 pH = 8

SepPak C18 pH = 11BondElut ENV pH = 5

BondElut ENV pH = 8

BondElut ENV pH =11

Figure 1 Optimization of SPE cartridges

strength and sample volume over extraction process Theexperimental design was obtained using Statgraphics Plussoftware 51 and the statistics study was done with IBM SPSSStatistics 19 We assessed two levels and three parameters pH(3 and 8) ionic strength (0 and 30 of NaCl) and samplevolume (50 and 250mL) to obtain the influence of eachparameter and the variable correlation to each other In thisstudy it is observed that the ionic strength and sample volumehad the major influence on the recoveries of the analytesFor that a 32 factorial design to optimize these two variablesat three levels per parameter (0 15 and 30 of NaCl forionic strength and 50 100 y 250mL for sample volume) wasused Figure 2 shows the response surface obtained for theestriol and 17120572-ethinylestradiol The results obtained showedthat an increment of the ionic strength did not producean increase in the response area of the compound and theoptimum volume was 250mL Because of that a solutionwithout salt addition and 250mL of sample volume waschosen Finally the desorption volume (1mLofmethanol and2mL of methanol in one and two steps) and wash-step (5mL

ofMilli-Q water and 5mL ofMilli-Q water with 5 and 10 ofmethanol vv) were assayed to complete the optimization ofthe SPE process The optimum values were 2mL of methanolin one step and 5mL of Milli-Q water without methanolrespectively

In accordance with the obtained results the optimumconditions for SPE procedure were SepPak C

18cartridge

250mL of sample at pH = 8 and 0 of NaCl desorptionwith 2mL of methanol in one step and wash step with5mL of Milli-Q water In these conditions we achieved apreconcentration factor of 125 In Figure 3 a chromatogramwith the optimum conditions is shown where the peaksof all compounds in their corresponding transitions can beobserved

32 Analytical Parameters Because of the SPE optimizationthat was done only with fluorescent compounds (estriol 17120573-estradiol and 17120572-ethinylestradiol) it was necessary to studythe recoveries of all the hormonal compounds using theoptimized SPE-UHPLC-MSMSmethod All the compoundsunder study showed good recoveries over 73 except thediethylstilbestrol with a recovery of 507

A calibration curve was used for the quantification ofthe analytes by diluting the stock solution of each analyteinto the samples to concentrations ranging between 1 and100 120583gsdotLminus1 Analysis was conducted by UHPLC-MSMS andlinear calibration plots for each analyte (1199032 gt 099) wereobtained based on their chromatographic peak areas

The limit of detection (LOD) and the limit of quantifi-cation (LOQ) for each compound were calculated from thesignal-to-noise ratio of each individual peak The LOD wasdefined as the lowest concentration that gave a signal-to-noiseratio that was greater than 3 The LOQ was defined as thelowest concentration that gave a signal to noise ratio that wasgreater than 10The LODs ranged from015 to 935 ngsdotLminus1 andthe LOQs ranged from 049 to 3118 ngsdotLminus1

The performance and reliability of the process werestudied by determining the repeatability of the quantificationresults for all target analytes under the described conditionsusing six samples (119899 = 6) The relative standard deviations(RSDs) were lower than 84 in all cases indicating a

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 3: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Journal of Analytical Methods in Chemistry

Analysis and Fate of Emerging Pollutantsduring Water Treatment

Guest Editors Fei Qi Guang-Guo Ying Kaimin ShihJolanta Kumirska Elif Pehlivanoglu-Mantas and Xiaojun Luo

Copyright copy 2013 Hindawi Publishing Corporation All rights reserved

This is a special issue published in ldquoJournal of Analytical Methods in Chemistryrdquo All articles are open access articles distributed underthe Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium providedthe original work is properly cited

Editorial Board

M Abdel-Rehim SwedenH Y Aboul Enein EgyptSilvana Andreescu USAA N Anthemidis GreeceA N Araujo PortugalR W Arndt SwitzerlandAna Cristi B Dias BrazilPierangelo Bonini ItalyArthur C Brown USAAntony C Calokerinos GreeceRicardo J Cassella BrazilXin-Sheng Chai ChinaO Chailapakul ThailandXingguo Chen ChinaC Collombel FranceW T Corns UKMiguel de la Guardia SpainIvonne Delgadillo PortugalE Dellacassa UruguayCevdet Demir TurkeyM Bonner Denton USAGregory W Diachenko USAM E Diaz-Garcia SpainDieter M Drexler USAJianxiu Du ChinaJenny Emneus DenmarkG Eppe BelgiumJosep Esteve-Romero SpainO Fatibello-Filho BrazilPaul S Francis AustraliaJuan F Garcia-Reyes SpainC Georgiou GreeceKate Grudpan ThailandR Haeckel Germany

Arafa I Hamed EgyptKaroly Heberger HungaryBernd Hitzmann GermanyChih-Ching Huang TaiwanI Isildak TurkeyJaroon Jakmunee ThailandXiue Jiang ChinaSelhan Karagoz TurkeyHiroyuki Kataoka JapanSkip Kingston USAChristos Kontoyannis GreeceR Kowalski PolandAnnamalai S Kumar IndiaIlkeun Lee USAJoe Liscouski USAEulogio J Llorent-Martinez SpainMercedes G Lopez MexicoMiren Lopez de Alda SpainLarisa Lvova ItalyJos Carlos Marques PortugalChristophe A Marquette FranceJean Louis Marty FranceSomenath Mitra USASerban C Moldoveanu USAMaria B Montenegro PortugalG A Nagana Gowda USAMilka Neshkova BulgariaB Nikolova-Damyanova BulgariaSune Nygaard DenmarkC K OrdquoSullivan SpainGangfeng Ouyang ChinaSibel A Ozkan TurkeyVeronica Pino SpainKrystyna Pyrzynska Poland

Jose B Quintana SpainMohammad A Rashid BangladeshD P S Rathore IndiaPablo Richter ChileFabio R P Rocha BrazilErwin Rosenberg AustriaGiuseppe Ruberto ItalyAntonio R Medina SpainBradley B Schneider CanadaGuoyue Shi ChinaJesus S Gandara SpainHana Sklenarova Czech RepublicN H Snow USAP B Stockwell UKF O Suliman OmanIt-Koon Tan SingaporeD G Themelis GreeceNilgun Tokman TurkeyNelson Torto South AfricaMarek Trojanowicz PolandParis Tzanavaras GreeceBengi Uslu TurkeyKrishna K Verma IndiaAdam Voelkel PolandFang Wang USAHai-Long Wu ChinaHui-Fen Wu TaiwanQingli Wu USAMengxia Xie ChinaRongda Xu USAXiu-Ping Yan ChinaLu Yang CanadaC Yin China

Contents

Analysis and Fate of Emerging Pollutants during Water Treatment Fei Qi Guang-Guo Ying Kaimin ShihJolanta Kumirska Elif Pehlivanoglu-Mantas and Xiaojun LuoVolume 2013 Article ID 256956 1 page

Occurrence and Removal Characteristics of Phthalate Esters from Typical Water Sources in NortheastChina Yu Liu Zhonglin Chen and Jimin ShenVolume 2013 Article ID 419349 8 pages

Simultaneous Determination of Hormonal Residues in Treated Waters Using Ultrahigh PerformanceLiquid Chromatography-Tandem Mass Spectrometry Rayco Guedes-Alonso Zoraida Sosa-Ferreraand Jose Juan Santana-RodrıguezVolume 2013 Article ID 210653 8 pages

Removal Efficiency and Mechanism of Sulfamethoxazole in Aqueous Solution by Bioflocculant MFXJie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei WeiVolume 2013 Article ID 568614 8 pages

Pyrite Passivation by Triethylenetetramine An Electrochemical Study Yun Liu Zhi Dang Yin Xuand Tianyuan XuVolume 2013 Article ID 387124 8 pages

A Green Preconcentration Method for Determination of Cobalt and Lead in Fresh Surface and WasteWater Samples Prior to Flame Atomic Absorption Spectrometry Naeemullah Tasneem Gul KaziFaheem Shah Hassan Imran Afridi Sumaira Khan Sadaf Sadia Arian and Kapil Dev BrahmanVolume 2012 Article ID 713862 8 pages

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 256956 1 pagehttpdxdoiorg1011552013256956

EditorialAnalysis and Fate of Emerging Pollutants duringWater Treatment

Fei Qi1 Guang-Guo Ying2 Kaimin Shih3 Jolanta Kumirska4

Elif Pehlivanoglu-Mantas5 and Xiaojun Luo2

1 Beijing Key Lab for Source Control Technology of Water Pollution College of Environmental Science and EngineeringBeijing Forestry University No 35 Qinghua East Road Beijing 100083 China

2 State Key Laboratory of Organic Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of SciencesGuangzhou 510640 China

3Department of Civil Engineering The University of Hong Kong Pokfulam Road Hong Kong4Department of Environmental Analysis Faculty of Chemistry University of Gdansk Sobieskiego 1819 80-952 Gdansk Poland5 Environmental Engineering Department Istanbul Technical University Ayazaga Campus Maslak 34469 Istanbul Turkey

Correspondence should be addressed to Fei Qi qifeibjfueducn

Received 23 April 2013 Accepted 23 April 2013

Copyright copy 2013 Fei Qi et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Emerging pollutants defined as compounds that are notcurrently covered by existing water-quality regulations allover the world have not been studied widely before and arethought to be potential threats to environmental ecosystemsand human health This special issue compiles 5 excitingpapers which are very meticulously performed researches

Generally emerging pollutants encompass a diversegroup of compounds including pharmaceuticals drugs ofabuse personal-care products (PCPs) steroids and hor-mones surfactants perfluorinated compounds (PFCs) flameretardants industrial additives and agents gasoline additivesnew disinfection byproducts (DBPs) nanomaterials and thetoxic minerals

The analysis methods occurrence and fate of hormonaland endocrine disruptors compounds (EDCs) were dis-cussed in two papers of this special issue R Guedes-Alonsoet al determine the hormonal residues in treated water byultrahigh performance liquid chromatography-tandem massspectrometry (UPLC-MS) and evaluate the efficiency ofthe conventional wastewater treatment for the removal ofhormonal compounds Moreover Y Liu et al study anotherkinds of PPCPs named as phthalate esters that is typicalkind of EDCs The occurrence in a surface water and theremoval efficiency in a traditional drinking water treatmentpalnt are studied According to results of the two papers

the occurrence and fate of hormonal and EDCs in water orwastewater treatment are very clear

J Xing et al report a new wastewater treatment technol-ogy bioflocculation for the removal of sulfamethoxazole thatis a typical pharmaceutical in wastewater The performanceand the reaction mechanism of the biodegradation of sul-famethoxazole by the bioflocculation are discussed in depthMoreover the optimum reaction condition is obtained

The heavy metal and toxic mineral are also importantpollutants in the environment especially in the mining areaTwo papers of this issue are focused on this K Naeemul-lah et al report a green preconcentration method for thedetermination of cobalt and lead in water Y Liu et al do anovel research on the electrochemical reaction of pyrite as asimulation of the natural environmental

By compiling this special issue we hope to enrich ourreaders and researchers on the analysis and fate of emergingpollutants during water treatment

Fei QiGuang-Guo Ying

Kaimin ShihJolanta Kumirska

Elif Pehlivanoglu-MantasXiaojun Luo

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 419349 8 pageshttpdxdoiorg1011552013419349

Research ArticleOccurrence and Removal Characteristics of Phthalate Estersfrom Typical Water Sources in Northeast China

Yu Liu Zhonglin Chen and Jimin Shen

State Key Laboratory of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Jimin Shen shenjiminhiteducn

Received 21 December 2012 Accepted 3 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Yu Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The presence of phthalate esters (PAEs) in the environment has gained a considerable attention due to their potential impactson public health This study reports the first data on the occurrence of 15 PAEs in the water near the Mopanshan Reservoirmdashthenew and important water source of Harbin city in Northeast China As drinking water is a major source for human exposureto PAEs the fate of target PAEs in the two waterworks (Mopanshan Waterworks and Seven Waterworks) was also analyzed Theresults demonstrated that the total concentrations of 15 PAEs in the water near the Mopanshan Reservoir were relatively moderateranging from 3558 to 92265 ngL with the mean value of 29431 ngL DBP and DEHP dominated the PAE concentrations whichranged from 525 to 44982 ngL and 1289 to 65709 ngL respectivelyThe occurrence and concentrations of these compoundswereheavily spatially dependent Meanwhile the results on the waterworks samples suggested no significant differences in PAE levelswith the input of the raw waters Without effective and stable removal of PAEs after the conventional drinking water treatment inthe waterworks (258 to 765) the risks posed by PAEs through drinking water ingestion were still existing which should bepaid special attention to the source control in theMopanshan Reservoir and some advanced treatment processes for drinking watersupplies

1 Introduction

Phthalate acid esters a class of chemical compounds mainlyused as plasticizers for polyvinyl chloride (PVC) or to alesser extent other resins in different industrial activities areubiquitous in the environment and have evoked interest inthe past decade due to endocrine disrupting effects and theirpotential impacts on public health [1ndash3]

Worldwide production of PAEs is approximately 6 mil-lion tons per year [4] As PAEs are not chemically boundto the polymeric matrix in soft plastics they can enter theenvironment by losses during manufacturing processes andby leaching or evaporating from final products [5]Thereforethe occurrence and fate of specific PAEs in natural waterenvironments have been observed and also there are a lot ofconsiderable controversies with respect to the safety of PAEsin water [5ndash10]

Six PAE compounds including dimethyl (DMP) diethyl(DEP) dibutyl (DBP) butylbenzyl (BBP) di(2-ethylhexyl)

(DEHP) and di-n-octyl phthalate (DNOP) are classifiedas priority pollutants by the US Environmental ProtectionAgency (EPA) Though the toxicity of PAEs to humans hasnot been well documented for some years the Ministry ofEnvironmental Protection in China has regulated phthalatesas environmental pollutants In addition the standard inChina concerning analytical controls on drinkingwaters doesnot specifically identify any PAEs as organic pollutant indexesto be determined by the new drinking water standard in 2007(Standard for drinking water quality GB5749-2006) whichwas forced to be monitored for the drinking water supplies in2012 Consequently official data about the presence of thesepollutants in the aquatic environment of some cities are notavailable

Harbin the capital of Heilongjiang Province is a typicallyold industrial base and economically developed city with apopulation of over 3million inNortheast China As the newlyenabledwater source forHarbin cityMopanshanwaterworkssupply the whole city with drinking water through long

2 Journal of Analytical Methods in Chemistry

China

HarbinMopanshan

Reservoir

LongfengshanReservoir

Figure 1 Spatial distribution of the 16 sampling sites near the Mopanshan Reservoir in Northeast China

distance transfer from the Mopanshan Reservoir To theauthorsrsquo knowledge the occurrence and fate of PAEs in thewater near this area and its relative waterworks have notpreviously been examined

The objectives of this study were (i) to determine theoccurrence of PAEs and clarify the fate and distribution ofthe pollutants in the water source (ii) to examine the twowaterworks where traditional drinking water treatment stepwas evaluated on the PAEs removal efficiencies and (iii) toevaluate the potential for adverse effects of PAEs on humanhealth Therefore the investigation of PAEs in the water canprovide a valuable record of contamination in Harbin city

2 Materials and Methods

21 Chemical Fifteen PAEs standard mixture includingdimethyl phthalate diethyl phthalate diisobutyl phthalatedi-n-butyl phthalate di(4-methyl-2-pentyl) phthalate di(2-ethoxyethyl) phthalate di-n-amyl phthalate di-n-hexylphthalate butyl benzyl phthalate di(hexyl-2-ethylhexyl)phthalate di(2-n-butoxyethyl) phthalate dicyclohexyl phthal-ate di(2-ethylhexyl) phthalate di-n-nonyl phthalate di-n-octylphthalate at 1000 120583gmL each and surrogate standardsconsisting of diisophenyl phthalate di-n-phenyl phthal-ate and di-n-benzyl phthalate in a mixture solution of500120583gmL each were supplied by AccuStandard Inc Asthe internal standard benzyl benzoate was also purchasedfrom AccuStandard Inc All solvents (acetone hexane anddichloromethane) used were HPLC-grade and were pur-chased from J T Baker Co (USA) Anhydrous sodiumsulfate (Tianjin Chengguang Chemical Reagent Co China)was cleaned at 600∘C for 6 h and then kept in a desiccatorbefore use

22 Sample Collection and Preparation Harbin the capitalof Heilongjiang province in China imports nearly all of itsdrinking water from two sources the Mopanshan Reservoir

Raw water Coagulation sedimentation Filtration Tank

Sampling site Sampling site

Figure 2 Schematic diagram of the waterworks

(long-distance transport project) and the Songhua River (oldwater source)

Water samples from the Mopanshan Reservoir andMopanshan waterwork were collected in 2008 The locationsof the sampling sites near the Mopanshan Reservoir are pre-sented in Figure 1 as a comparison sampling from anotherHarbin water supplymdashSeven waterworks with water sourcefrom the SonghuaRiverwas performed in 2011 In eachwater-works with considering the hydraulic retention time threesets of raw water samples (influent) were taken and thenthe final finished waters (effluent) after the whole treatmentprocess were carried out for the collectionsThe flow diagramof the waterworks is shown in Figure 2

Samples were collected using 20 L glass jars from 05mbelow the water surface During the whole sampling processthe global position system was used to locate the samplingstations (details in Table 1) All samples were transferred tothe laboratory directly after sampling and stored at 4∘C priorto extraction within 2 d

Water samples were filtered under vacuum through glassfiber filters (07 120583mpore sizes) Prior to extraction each sam-ple was spiked with surrogate standards The water sampleswere extracted based on a classical liquid phase extractionmethod (USEPA method 8061) with slight modificationsBriefly 1 L of water samples was placed in a separating funneland extracted by means of mechanical shaking with 150mLdichloromethane and then with filtration on sodium sulfate(about 20 g) the organic extracts were concentrated usinga rotary evaporator The exchange of solvent was done byreplacing dichloromethane with hexane Finally they were

Journal of Analytical Methods in Chemistry 3

Table 1 Detailed descriptions of the sampling locations

Number Sampling site Name Latitude Longitude1 Lalin Jinsan Bridge Mangniu River E127∘0210158405310158401015840 N45∘510158404510158401015840

2 Xingsheng Town Gaojiatun Lalin River E127∘0610158401110158401015840 N44∘5110158405710158401015840

3 Dujia Town Shuguang Lalin River E127∘1010158404410158401015840 N44∘4810158404110158401015840

4 Shanhe Town Taipingchuan Lalin River E127∘1810158403610158401015840 N44∘4310158405010158401015840

5 Xiaoyang Town Qichuankou Lalin River E127∘2310158405410158401015840 N44∘3910158404610158401015840

6 Shahezi Town Mopanshan Reservoir E127∘3810158405910158401015840 N44∘2410158401710158401015840

7 Shahezi Town Gali Lalin River E127∘3510158401710158401015840 N44∘3110158405610158401015840

8 Chonghe Town Changcuizi Mangniu River E127∘4610158403610158401015840 N44∘3510158404610158401015840

9 Chonghe Town Xingguo Mangniu River E127∘3510158401710158401015840 N44∘3110158405710158401015840

10 Longfeng Town Mangniu River E127∘3510158401910158401015840 N44∘4310158404810158401015840

11 Changpu Town Zhonghua Mangniu River E127∘1610158403010158401015840 N45∘110158404210158401015840

12 Erhe Town Shuanghe Mangniu River E127∘1810158403210158401015840 N45∘410158402810158401015840

13 Zhiguang Town Songjiajie Mangniu River E127∘341015840310158401015840 N45∘110158402010158401015840

14 Zhiguang Town Wuxing Mangniu River E127∘2910158402010158401015840 N45∘010158404310158401015840

15 Changpu Town Xingzhuang Mangniu River E127∘1010158404210158401015840 N45∘410158403610158401015840

16 Yingchang Town Xingguang Lalin River E126∘551015840810158401015840 N45∘91015840010158401015840

reduced to 05mL under gentle nitrogen flow The internalstandard was added to the sample prior to instrumentalanalysis

23 Chemical Analysis The extracted compounds weredetermined by gas chromatography coupled to mass spec-trometer analysis as described in other publications [1112] Briefly extracted samples were injected into an Agilent6890 Series GC equipped with a DB-35MS capillary column(Agilent 30m times 025mm id 025120583m film thickness) andan Agilent 5973 MS detector operating in the selective ionmonitoring mode The column temperature was initially setat 70∘C for 1min then ramped at 10∘Cmin to 300∘C andheld constant for 10min The transfer line and the ion sourcetemperature were maintained at 280 and 250∘C respectivelyHelium was used as the carrier gas at a flow rate of 1mLminThe extracts (20 120583L) were injected in splitless mode with aninlet temperature of 300∘C

24 Quality Assurance and Quality Control All glasswarewas properly cleaned with acetone and dichloromethanebefore use Laboratory reagent and instrumental blanks wereanalyzed with each batch of samples to check for possiblecontamination and interferences Only small levels of PAEswere found in procedural blanks in some batches andthe background subtraction was appropriately performed inthe quantification of concentration in the water samplesCalibration curves were obtained from at least 3 replicateanalyses of each standard solution The surrogate standardswere added to all the samples to monitor matrix effectsRecoveries of PAEs ranged from 62 to 112 in the spikedwater and the surrogate recoveries were 751 plusmn 127 fordiisophenyl phthalate 723 plusmn 143 for di-n-phenyl phtha-late and 1026 plusmn 104 for di-n-benzyl phthalate in thewater samples The determination limits ranged from 6 to30 ngL A midpoint calibration check standard was injected

as a check for instrumental drift in sensitivity after every10 samples and a pure solvent (methanol) was injected as acheck for carryover of PAEs from sample to sample All theconcentrations were not corrected for the recoveries of thesurrogate standards

3 Results and Discussion

31 PAEs in Water Source The PAEs in the waters fromthe sampling sites near the Mopanshan Reservoir wereinvestigated and the results are presented in Table 2 Thesum15

PAEs concentrations ranged from 3558 to 92265 ngLwith the geometric mean value of 29431 ngL Among the15 PAEs detected in the waters DIBP DBP and DEHP weremeasured in all the samples with the average concentrationsbeing 1966 8014 and 17741 ngL respectively The threePAE congeners are important and popular addictives inmany industrial products including flexible PVC materialsand household products suggesting the main source of PAEcontaminants in the water [13] The correlations of the con-centration of DEHP DBP and DIBP with the concentrationsof total PAEs in the water samples are shown in Figure 3and a relatively significant correlation between sum

15

PAEs andDEHP concentration was found suggesting the importantpart played by DEHP in total concentrations of PAEs inthe water bodies near the Mopanshan Reservoir In otherwords the contribution of DEHP to total PAEs was higherthan that of other PAE congeners in the water samples Inaddition DMP DEP and DNOP with the mean value of140 284 and 541 ngL respectively only detected at somesampling sites and have also attracted much attention asthe priority pollutants by the China National EnvironmentalMonitoring Center On the contrary the concentrations of6 PAEs (DMEP BMPP BBP DBEP DCHP and DNP) werebelow detection limits in all the water samples near theMopanshan Reservoir which is easily explained in terms ofmuch lower quantities of present use in China

4 Journal of Analytical Methods in Chemistry

0 2000 4000 6000 80000

2000

4000

6000

Con

cent

ratio

ns (n

gL)

DEHP

119903 = 0885 119875 lt 001

sum15PAEs (ngL)

(a)

0 2000 4000 6000 80000

2000

4000

Con

cent

ratio

ns (n

gL)

sum15PAEs (ngL)

DBP

119903 = 0812 119875 lt 001

(b)

1000

500

0

0 2000 4000 6000 8000sum15PAEs (ngL)

DIBP

Con

cent

ratio

ns (n

gL)

119903 = 0724 119875 lt 001

(c)

Figure 3 Correlations of the concentration of the major PAEs (DEHP DBP and DIBP) with the concentrations of total PAEs in the watersamples

Table 2 Concentrations of 15 PAEs in water samples near the Mopanshan Reservoir

PAEs Abbreviation Water (ngL)Range Mean Frequency

Dimethyl phthalate DMP ndndash424 140 816Diethyl phthalate DEP ndndash550 284 1516Diisobutyl phthalate DIBP 400ndash6588 1966 1616Dibutyl phthalate DBP 525ndash44982 8014 1616bis(2-methoxyethyl)phthalate DMEP nd nd 016bis(4-methyl-2-pentyl)phthalate BMPP nd nd 016bis(2-ethoxyethyl)phthalate DEEP ndndash546 128 516Dipentyl phthalate DPP ndndash925 455 1016Dihexyl phthalate DHXP ndndash651 162 516Benzyl butyl phthalate BBP nd nd 016bis(2-n-butoxyethyl)phthalate DBEP nd nd 016Dicyclohexyl phthalate DCHP nd nd 016bis(2-ethylhexyl)phthalate DEHP 1289ndash65709 17741 1616Di-n-octyl phthalate DNOP ndndash4482 541 516Dinonyl phthalate DNP nd nd 016sum15

PAEs 3558ndash92265 29431 mdash

The distribution of 15 PAEs (sum15

PAEs) studied and6 US EPA priority PAEs (sum

6

PAEs including DMP DEPDIBP DBP DEHP and DNOP) in the waters from differentsampling sites are shown in Figure 4 There was an obviousvariation in the total sum

15

PAEs concentrations in water sam-ples near the Mopanshan Reservoir the concentrations ofsum6

PAEs from the same sampling sites varied from 2690 to90860 ngL with an average of 28686 ngL the distributionspectra of which observed for all the sampling sites weresimilar tosum

15

PAEsThe highest levels of PAEs contaminationwere seen on the sampling site 3 followed by some relativelyheavily polluted sites (site 16 13 9 10 and 11) indicating thatthese sites served as important PAE sources and the spatialdistribution of PAEs was site specific The levels in the watersexamined varied over a wide range especially in theMangniu

River near theMopanshan Reservoir (in some case overmorethan one order of magnitude) In general it should be notedthat there might be a relation of PAEs levels with the input oflocal waste such as sewage water food packaging and scrapmaterial near the sampling point which were found duringthe sampling period

32 PAE Congener Profiles in the Water Different PAE pat-terns may indicate different sources of PAEs Measurementof the individual PAE composition is helpful to track thecontaminant source and demonstrate the transport and fateof these compounds in water [11] The relative contributionsof the 9 detectable PAE congeners to thesum

15

PAEs concentra-tions in the water are presented in Figure 5 It is clear thatDEHP was the most abundant in the water samples with

Journal of Analytical Methods in Chemistry 5

0

500

1000

1500

4000

6000

8000

10000

Con

cent

ratio

ns (n

gL)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

sum15PAEssum6PAEs

Figure 4 Spatial distributions of the 16 sampling sites near theMopanshan Reservoir

the exception of site 2 3 and 11 contributions ranging from331 to 963 followed byDBP ranging from 21 to 363The results are consistent with the above data for overallanalysis that DBP and DEHP are the dominant componentsof the PAEs distribution pattern in each sampling site whichreflected the different pattern of plastic contaminant inputduring the sampling period Similarly DIBP and DBP areused in epoxy resins or special adhesive formulations withthe different proportions of these two PAE congeners whichwere also the important indicator of the information pollutedby PAEs for the sampling locations Although the limitedsample number draws only limited conclusions there is stillreason to note that a leaching from the plastic materials intothe runoff water is possible and that water runoff from thecontaminated water is a burden pathway from differentsources of PAEs [14]

33 Comparison with Other Water Bodies Comparison withthe total PAEs concentrations is nevertheless very limited dueto the different analysis compounds However the individualPAE namely DBP and DEHP is by far the most abundantin other researches and it is possible to make a camparisonwith our findings In this case the results of DBP and DEHPconcentrations published in literatures for kinds of waterbodies are presented together in Table 3

The DEHP and DBP concentrations of the present studyshowed to some extent lower concentration levels than thosereported in the other water bodies in China In comparisonthe results were comparable or similar to those from theexaminations described in other foreign countries For exam-ple as shown in Table 3 the DEHP concentrations were sim-ilar to the surface waters from the Netherlands and Italydescribed in the literature Meanwhile these concentrationsin this study were quite lower than the Yangtze River andSecond Songhua River in China

0

20

40

60

80

100

DEEP DPP DHXP DEHP DNOP DBP

DIBP DEP DMP

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

Com

posit

ion

()

Figure 5 PAE composition of thewater samples in 16 sampling sites

In conclusion as compared to the results of other studiesthe waters near the Mopanshan Reservoir were moderatelypolluted by PAEs Therefore there is a definite need to set upa properly planned and systematic approach to water controlnear the Mopanshan Reservoir

34 PAE Levels in the Waterworks The Mopanshan Water-works (MPSW) equipped essentially with the water sourceof the Mopanshan Reservoir has been investigated in orderto assess the fate of the PAEs during the drinking watertreatment process For comparison a sampling campaign forthe determination of PAEs levels in the Seven Waterworks(SW waterworks with the old water source of the SonghuaRiver) was carried out Both waterworks operate coagulationsedimentation and followed by filtration treatment processwhich are typical traditional drinking water treatment

The measured concentrations in the raw and finishedwater of the two investigated waterworks are shown inFigure 6 Six out of fifteen PAEs were detected in the fin-ished water from the two waterworks The detected PAEswere DMP DEP DIBP DBP DEHP and DNOP and theother investigated phthalates are of minor importance withconcentrations all below the limit of detection As showin Figure 6 the measured concentrations of the analyzedPAEs in the finished water of the two waterworks variedstronglyThemost important compound in the finishedwaterwas DEHP with the mean concentration of 34737 and40592 ngL for the MPSW and SW respectively suggestingthe highest relative composition of total PAE concentrationsin the drinking water

For the raw water from the different water sources DMPand DIBP concentrations in the MPSW were much lowerthan the ones in the SW and the concentrations of DEPDBP DEHP andDEHPwere relatively comparable in the two

6 Journal of Analytical Methods in Chemistry

Table 3 Comparison of the concentrations of DEHP and DBP in the water bodies (ngL)

Location DEHP DBP ReferenceRange Median Mean Range Median Mean

Surface water Germany 330ndash97800 2270 mdash 120ndash8800 500 mdash [14]Surface water the Netherlands ndndash5000 320 mdash 66ndash3100 250 mdash [15]Seine River estuary France 160ndash314 mdash mdash 67ndash319 mdash mdash [16]Tama River Japan 13ndash3600 mdash mdash 8ndash540 mdash mdash [17]Velino River Italy ndndash6400 mdash mdash ndndash44300 mdash mdash [2]Surface water Taiwan ndndash18500 mdash 9300 1000ndash13500 mdash 4900 [18]Surface water Jiangsu China 556ndash156707 mdash mdash 16ndash58575 mdash mdash [19]Yangtze River mainstream China 3900ndash54730 mdash mdash ndndash35650 mdash mdash [20]Middle and lower Yellow River China 347ndash31800 mdash mdash ndndash26000 mdash mdash [21]Second Songhua River China ndndash1752650 370020 mdash ndndash5616800 mdash 717240 [22]Urban lakes Guangzhou China 87ndash630 170 240 940ndash3600 1990 2030 [11]Xiangjiang River China 620ndash15230 mdash mdash mdash mdash mdash [23]This study 1289ndash65709 6710 17741 525ndash44982 1103 8014

0

500

1000

100001200014000

0

20

40

60

80

100

Raw waterFinished waterRemoval

Rem

oval

()

Con

cent

ratio

ns (n

gL)

DMP DEP DIBP DBP DEHP DNOP

(a)

Raw waterFinished waterRemoval

0

500

1000

1500

2000

100001200014000

0

20

40

60

80

100C

once

ntra

tions

(ng

L)

Rem

oval

()

DMP DEP DIBP DBP DEHP DNOP

(b)

Figure 6 PAEs detected in the water samples from the MPSW (a) and SW (b)

waterworks The removal of PAEs by these two waterworksranged from 258 to 765 which varied significantly with-out stable removal efficienciesThe lower removal efficienciesfor DMP and DNOP were observed in the SW with theremoval less than 30 For both the waterworks no soundremoval efficiencies were obtained for the PAEs indicatingthat the traditional drinking water treatment cannot showgood performance to eliminate these micro pollutants whichhas nothing to do with the type of the water source

Traditional drinking water treatment focuses on dealingwith the particles and colloids in terms of physical processesMany studies of the environmental fates of PAEs have demon-strated that oxidation or microbial action is the principalmechanism for their removal in the aquatic systems [24ndash26]Therefore the treatment process should be the combinationswith the key techniques for removing PAEs from the waterOn the other hand since the removal efficiencies of PAEs by

these advance drinking water treatments in waterworks hasnot been systematically studied to date further research inthis direction would seem to be required

35 Exposure Assessment of PAEs in Water To evaluate thepotential and adverse effects of PAEs quality guidelines forsurface water and drinking water standard were used Theresults indicated that the mean concentrations of DBP andDEHP at levels were well below the reference doses (RfD)regarded as unsafe by the EPA for the surface water Thelevels were not also above the RfD recommended by China(Environmental Quality Standard for SurfaceWater of ChinaGB3838-2002) On the other hand the amounts of DEHPpresent in public water supplies should be lower than thedrinkingwater standard (0006mgL for EPA and 0008mgLfor China) According to the results the concentrations of

Journal of Analytical Methods in Chemistry 7

DEHP in drinkingwater samples from theMPSWwere lowerthan the limited value

PAEs are also considered to be endocrine disruptingchemicals (EDCs) whose effects may not appear until long-term exposure According to the results PAEs were detectedin the drinking water constantly ingested in daily life indi-cating that drinking water is an important source of humanexposure to PAEs contaminants Assuming a daily waterconsumption rate of 2 L and an average body weight of 60 kgfor adults the average daily intake of DEHP DBP and DIBPby way of drinking water from MPSW was calculated to be1158 1352 and 81 ngkgd respectively In comparison thevalues of SW with the water source of the Songhua Riverwere relatively higher with the calculated results of 1353140 and 155 ngkgd for DEHP DBP and DIBP respectivelyIn this study the estimated daily intake levels of DEHPfrom the drinking water were quite lower than the RfDof 20000 ngkgd released by the EPA However some ofPAEs are partly metabolised in the organism and futureexperiments should be focused on determining the potentialeffects of the metabolites [27]

Currently treated water from the Songhua River is fornonpotable uses and MPSW is the exclusive waterworks runfor the water supply of Harbin city However populationgrowth and drought cycle are limited by the availability of rawwater from theMopanshan Reservoir Tomeet the increasingdemand local and regional water authorities have begun acampaign of second water supply project from the SonghuaRiver again which needs the protection of the Songhua Riverand advanced water treatment for the source

4 Conclusions

This study provided the first detailed data on the contami-nation status of 15 PAEs in the water near the MopanshanReservoir The concentration range of 15 PAEs in the sampleswas from 3558 to 92265 ngL with the mean value of29431 ngL DEHP andDBPwere themain pollutants among15 PAEs accounting for the main watershed pollution Theoccurrence and distribution of PAEs from different samplingsites in the water source varied largely suggesting that thespatial distribution of PAEs was site specific In additionthe monitoring of PAEs in the waterworks also showed thatPAEs can be detected in the drinking water and certaintoxicological risks to drinking water consumers were foundThese results reported here contribute to an understandingof how PAE contaminants are distributed in the new watersource and the waterworks in Harbin city as well as forminga basis for further modeling risk assessment and selection ofdrinking water treatment technology

In conclusion the results implied that no urgent reme-diation measures were required with respect to PAEs in thewaters However the ecological and health effects of thesesubstances through drinkingwater at the relatively lower con-centrations still need further notice in light of their possiblebiological magnifications Therefore the long-term sourcecontrol in the water and adding advanced treatment processfor drinking water supplies should be given special attentionin this area

Acknowledgments

This work was supported by the National Natural ScienceFoundation of China (1077029) the Funds for CreativeResearch Groups of China (Grant no 51121062) the NationalNatural Science Foundation of China (51078105) and theOpen Project of the State Key Laboratory of Urban WaterResource and Environment Harbin Institute of Technology(no QA201019)

References

[1] M Nikonorow H Mazur and H Piekacz ldquoEffect of orallyadministered plasticizers and polyvinyl chloride stabilizers inthe ratrdquo Toxicology and Applied Pharmacology vol 26 no 2 pp253ndash259 1973

[2] M Vitali M Guidotti G Macilenti and C Cremisini ldquoPhtha-late esters in freshwaters asmarkers of contamination sourcesmdasha site study in ItalyrdquoEnvironment International vol 23 no 3 pp337ndash347 1997

[3] G Latini C de Felice G Presta et al ldquoIn utero exposure todi-(2-ethylhexyl)phthalate and duration of human pregnancyrdquoEnvironmental Health Perspectives vol 111 no 14 pp 1783ndash17852003

[4] C E Mackintosh J A Maldonado M G Ikonomou and F AP C Gobas ldquoSorption of phthalate esters and PCBs in a marineecosystemrdquo Environmental Science and Technology vol 40 no11 pp 3481ndash3488 2006

[5] M Clara G Windhofer W Hartl et al ldquoOccurrence of phtha-lates in surface runoff untreated and treated wastewater andfate during wastewater treatmentrdquo Chemosphere vol 78 no 9pp 1078ndash1084 2010

[6] M M Abdel Daiem J Rivera-Utrilla R Ocampo-Perez J DMendez-Dıaz andM Sanchez-Polo ldquoEnvironmental impact ofphthalic acid esters and their removal fromwater and sedimentsby different technologiesmdasha reviewrdquo Journal of EnvironmentalManagement vol 109 pp 164ndash178 2012

[7] L Chen Y Zhao L Li B Chen and Y Zhang ldquoExposureassessment of phthalates in non-occupational populations inChinardquo Science of the Total Environment vol 427-428 pp 60ndash69 2012

[8] M J Teil M Blanchard andM Chevreuil ldquoAtmospheric fate ofphthalate esters in an urban area (Paris-France)rdquo Science of theTotal Environment vol 354 no 2-3 pp 212ndash223 2006

[9] P Roslev K Vorkamp J Aarup K Frederiksen and P HNielsen ldquoDegradation of phthalate esters in an activated sludgewastewater treatment plantrdquo Water Research vol 41 no 5 pp969ndash976 2007

[10] J Gasperi S Garnaud V Rocher and R Moilleron ldquoPrioritypollutants in wastewater and combined sewer overflowrdquo Scienceof the Total Environment vol 407 no 1 pp 263ndash272 2008

[11] F Zeng K Cui Z Xie et al ldquoOccurrence of phthalate estersin water and sediment of urban lakes in a subtropical cityGuangzhou South Chinardquo Environment International vol 34no 3 pp 372ndash380 2008

[12] F Zeng K Cui Z Xie et al ldquoPhthalate esters (PAEs) emergingorganic contaminants in agricultural soils in peri-urban areasaround Guangzhou Chinardquo Environmental Pollution vol 156no 2 pp 425ndash434 2008

[13] G Wildbrett ldquoDiffusion of phthalic acid esters from PVC milktubingrdquo Environmental Health Perspectives vol 3 pp 29ndash351973

8 Journal of Analytical Methods in Chemistry

[14] H Fromme T Kuchler T Otto K Pilz J Muller and AWenzel ldquoOccurrence of phthalates and bisphenol A and F inthe environmentrdquoWater Research vol 36 no 6 pp 1429ndash14382002

[15] A D Vethaak J Lahr S M Schrap et al ldquoAn integrated assess-ment of estrogenic contamination and biological effects in theaquatic environment ofTheNetherlandsrdquoChemosphere vol 59no 4 pp 511ndash524 2005

[16] C Dargnat M Blanchard M Chevreuil andM J Teil ldquoOccur-rence of phthalate esters in the Seine River estuary (France)rdquoHydrological Processes vol 23 no 8 pp 1192ndash1201 2009

[17] T Suzuki K Yaguchi S Suzuki and T Suga ldquoMonitoring ofphthalic acid monoesters in river water by solid-phase extrac-tion and GC-MS determinationrdquo Environmental Science andTechnology vol 35 no 18 pp 3757ndash3763 2001

[18] S Y Yuan C Liu C S Liao and B V Chang ldquoOccurrenceand microbial degradation of phthalate esters in Taiwan riversedimentsrdquo Chemosphere vol 49 no 10 pp 1295ndash1299 2002

[19] B Li C Qu and J Bi ldquoIdentification of trace organic pollutantsin drinking water and the associated human health risks inJiangsu Province Chinardquo Bulletin of Environmental Contami-nation and Toxicology pp 1ndash5 2012

[20] F Wang X Xia and Y Sha ldquoDistribution of phthalic acidesters in Wuhan section of the Yangtze River Chinardquo Journalof Hazardous Materials vol 154 no 1ndash3 pp 317ndash324 2008

[21] Y J Sha X H Xia and X Q Xiao ldquoDistribution characters ofphthalic acid ester in the waters middle and lower reaches ofthe Yellow Riverrdquo China Environmental Science vol 26 no 1pp 120ndash124 2006

[22] J Lu L-B Hao C-Z Wang W Li R-J Bai and D YanldquoDistribution characteristics of phthalic acid esters in middleand lower reaches of no 2 Songhua Riverrdquo EnvironmentalScience amp Technology vol 12 article 014 2007

[23] X J Zhu and Y Y Qiu ldquoMeasuring the phthalates of xiangjiangriver using liquid-liquid extraction gas chromatographyrdquoAdvanced Materials Research vol 301 pp 752ndash755 2011

[24] B L Yuan X Z Li and N Graham ldquoAqueous oxida-tion of dimethyl phthalate in a Fe(VI)-TiO

2

-UV reaction sys-temrdquoWater Research vol 42 no 6-7 pp 1413ndash1420 2008

[25] Z Yunrui ZWanpeng L FudongW Jianbing and Y ShaoxialdquoCatalytic activity of RuAl2O3 for ozonation of dimethylphthalate in aqueous solutionrdquo Chemosphere vol 66 no 1 pp145ndash150 2007

[26] H N Gavala U Yenal and B K Ahring ldquoThermal andenzymatic pretreatment of sludge containing phthalate estersprior tomesophilic anaerobic digestionrdquoBiotechnology and Bio-engineering vol 85 no 5 pp 561ndash567 2004

[27] Y Guo Q Wu and K Kannan ldquoPhthalate metabolites in urinefrom China and implications for human exposuresrdquo Environ-ment International vol 37 no 5 pp 893ndash898 2011

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 210653 8 pageshttpdxdoiorg1011552013210653

Research ArticleSimultaneous Determination of Hormonal Residuesin Treated Waters Using Ultrahigh Performance LiquidChromatography-Tandem Mass Spectrometry

Rayco Guedes-Alonso Zoraida Sosa-Ferrera and Joseacute Juan Santana-Rodriacuteguez

Departamento de Quımica Universidad de Las Palmas de Gran Canaria 35017 Las Palmas de Gran Canaria Spain

Correspondence should be addressed to Jose Juan Santana-Rodrıguez jsantanadquiulpgces

Received 28 December 2012 Accepted 7 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Rayco Guedes-Alonso et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

In the last years hormone consumption has increased exponentially Because of that hormone compounds are considered emergingpollutants since several studies have determinted their presence in water influents and effluents of wastewater treatment plants(WWTPs) In this study a quantitative method for the simultaneous determination of oestrogens (estrone 17120573-estradiol estriol17120572-ethinylestradiol and diethylstilbestrol) androgens (testosterone) and progestogens (norgestrel andmegestrol acetate) has beendeveloped to determine these compounds in wastewater samples Due to the very low concentrations of target compounds in theenvironment a solid phase extraction procedure has been optimized and developed to extract and preconcentrate the analytesDetermination and quantification were performed by ultrahigh performance liquid chromatography-tandem mass spectrometry(UHPLC-MSMS) The method developed presents satisfactory limits of detection (between 015 and 935 ngsdotLminus1) good recoveries(between 73 and 90 for the most of compounds) and low relative standard deviations (under 84) Samples from influents andeffluents of two wastewater treatment plants of Gran Canaria (Spain) were analyzed using the proposed method finding severalhormones with concentrations ranged from 5 to 300 ngsdotLminus1

1 Introduction

In general it is supposed that more than 100000 differentchemical compounds can be introduced in the Environmentmany of them in very small quantity However a lot of thesecompounds are not included as pollutants in the legislationAlthough these compounds named emerging pollutants arenot regulated as pollutants they probably will be in the futurebecause of their potential negative effect in the ecosystem For20 years many articles have reported the presence of theseldquonew compoundsrdquo in wastewater [1 2]

The emerging pollutant origin is mainly anthropogenicconsidering that the majority of these compounds are bio-logically active substances that are synthesized to use themin agriculture industry and medicine The main source ofthese emerging pollutants is the residual urbanwaters and thewastewater treatment plants effluents because many of these

WWTPs are not designed or optimized to treat this kind ofcompounds [3]

Hormones are one of the most potent endocrine disrupt-ing compounds as well as are considered also as emergingpollutants Hormones can be differentiated in oestrogensandrogens and progestogens Some of them have limits intheir use but not a specific legislation [4]

The main characteristic of these pollutants is that it isnot necessary to remain in the environment to cause negativeeffects in view of the fact that their constant introduction init offsets their removal or degradation [5]

The steroid hormones help controlling the metabolisminflammations immunological functions water and salt bal-ance sexual development and the capacity of withstandingillnesses [6] The term steroid can be used for naturalhormones produced by the body as well as for artificiallyproduced medicines that increase the natural steroid effect

2 Journal of Analytical Methods in Chemistry

In the last 50 years the natural and synthetic hormoneworldwide consumption has grown as much as in humanmedicine as in cattle farming and they become the mostprescribed medicines [7]

A significant quantity of consumed oestrogens leaves theorganism through excretions For example 17120573-estradiol (E2)is oxidized rapidly becoming an estrone (E1) that can turninto estriol afterwards (E3) Besides the 17120572-ethinyl estradiol(EE) is excreted as conjugated [8]

With regard to emission sources in the first place arethe wastewater treatment plants (WWTPs) [9] and secon-darily cattle waste such as those leachates from dung anduncontrolled dumping [10] Several studies made in theWWTPs have reported that the treatment plants are capableof eliminating around 60 of hormones [11ndash13]

The identification of hormone residues in environmentis of special interest because knowledge of these compoundsis a requirement to take measures in order to regulate andminimize their environmental impact

However measurement of hormone residues is a verydifficult task not only due to the difficulty in measuringvery low concentration but also due to a very complexityof the samples Therefore use of mass spectrometer (MS)as detector coupled with chromatography techniques hasbecome a powerful method for the analysis of these typesof compounds at trace levels [14ndash17] Consequently LC-MSMS is the principally chosen technique One of the mainadvantages of LC-MSMS is its ability to analyze hormoneswithout derivatization (necessary in GC) or the need ofhydrolyze the conjugated form

Due to low level concentration of these compounds inenvironmental water it is necessary to apply an extractionand preconcentration method prior to LC analysis The mostused technique of extraction and preconcentration methodfor liquid samples is the solid phase extraction (SPE) [18ndash20]

The objective of this study is to develop a rapid and simpleprocedure of extraction preconcentration and determina-tion of four steroid oestrogens (estrone (E1) 17120573-estradiol(E2) estriol (E3) and 17120572-ethinylestradiol (EE)) one non-steroidal oestrogen the diethylstilbestrol (DES) one andro-gen the testosterone (TES) and two synthetic progestogensnorgestrel (NOR) and megestrol acetate (MGA) (Table 1)based on solid phase extraction and ultrahigh performanceliquid chromatography-tandem mass spectrometry (SPE-UHPLC-MSMS) The developed method was applied tothe identification and quantification of these compoundsin wastewater samples obtained from the influents andeffluents of two wastewater treatment plants (WWTPs) ofGran Canaria (Spain) They presented different methodsof wastewater treatments WWTP 1 presented a traditionalmethod based on activated sludge while WWTP 2 used amembrane bioreactor technique

2 Materials and Methods

21 Reagents All of the hormonal compounds usedwere pur-chased from Sigma-Aldrich (Madrid Spain) Stock solutionscontaining 1000mgsdotLminus1 of each analyte were prepared by

dissolving the compound inmethanol and the solutionswerestored in glass-stoppered bottles at 4∘C prior to use Workingaqueous standard solutions were prepared daily Ultrapurewater was provided by a Milli-Q system (Millipore BedfordMA USA) HPLC-grade methanol LC-MS methanol andLC-MS water as well as the ammonia and the ammoniumacetate used to adjust the pH of the mobile phases wereobtained from Panreac Quımica (Barcelona Spain)

22 Sample Collection Water samples were collected fromthe effluents of twowastewater treatment plants located in thenorthern area of Gran Canaria in May and August of 2012WWTP 1 used a conventional activated sludge treatmentsystem while WWTP 2 employed a membrane bioreactortreatment system The samples were collected in 2 L amberglass bottles that were rinsed beforehand with methanol andultrapurewater Samples were purified through filtrationwithfibreglass filters and then with 065 120583m membrane filters(Millipore Ireland) The samples were stored in the dark at4∘C and extracted within 48 hours

23 Instrumentation For the SPE optimization the instru-ment used was an ultrahigh performance liquid chromatog-raphy with fluorescence detector (UHPLC-FD) system con-sisting of an ACQUITYQuaternary Solvent Manager (QSM)used to load samples and wash and recondition the analyticalcolumn an autosampler a column manager and a fluores-cence detector with excitation and emission wavelengths of280 and 310 nm respectively all fromWaters (Madrid Spain)

The analysis of wastewater samples was performed ina UHPLC-MSMS system from Waters (Madrid Spain)similar to the described above with a 2777 autosamplerequipped with a 25120583L syringe and a tray to hold 2mLvials and an ACQUITY tandem triple quadrupole (TQD)mass spectrometer with an electrospray ionization (ESI)interface All Waters components (Madrid Spain) werecontrolled using the MassLynx Mass Spectrometry SoftwareElectrospray ionisation parameters were fixed as followsthe capillary voltage was 3 kV in positive mode and minus2 kVin negative mode the source temperature was 150∘C thedesolvation temperature was 500∘C and the desolvation gasflow rate was 1000 Lhr Nitrogen was used as the desolvationgas and argon was employed as the collision gas

The detailed MSMS detection parameters for each hor-monal compound are presented in Table 2 and were opti-mised by the direct injection of a 1mgsdotLminus1 standard solutionof each analyte into the detector at a flow rate of 10 120583Lsdotminminus1

24 Chromatographic Conditions For the SPE optimizationthe analytical column was a 50mm times 21mm ACQUITYUHPLCBEHWaters C

18columnwith a particle size of 17120583m

(Waters Chromatography Barcelona Spain) operating at atemperature of 30∘C Analytes separation was carried outemploying the following gradient starting at 55 45 (vv)water methanol for 1 minute During 3 minutes it changedto 50 50 (vv) and stayed for 25 minutes more Finally cameback to initial conditions in 1 minute and stayed for 15

Journal of Analytical Methods in Chemistry 3

Table 1 List of hormonal compounds pKa values chemical structure and retention times

Compound pKa [21] Structure 119905119877

(min)

E3 Estriol 103

HO

OH

OH

H H

H096

E2 17120573-estradiol 103

HO

OH

H H

H218

EE 17120572-ethinylestradiol 103

HO

HO

H H

H223

E1 Estrone 103

HO

O

H

H H220

DES Diethylstilbestrol 102

HO

OH

235

TES Testosterone 151

OH

OH H

H240

MGA Megestrol acetate

O

O

O

OH

H

H306

NOR Levonorgestrel 131

OH

O

H

H

H

H263

minutes Therefore the analysis took 9 minutes at a flow of05mLsdotminminus1

For the analysis of real samples aUHPLC-MSMS systemwas used The analytical column was the same and themobile phase was water and methanol adjusted with a bufferconsisting in 01 vv ammonia and 15mM of ammoniumacetate The analysis was performed in gradient mode at aflow rate of 03mLsdotminminus1The gradient started at 50 50 (vv)mixture of water methanol which changed to 25 75 (vv) in3 minutes and returned to 50 50 in 1 minute more Finallythe gradient stayed calibrating for another 15 minutes moreThe sample volume injected was 5120583L

3 Results and Discussion

31 Optimization of Solid-Phase Extraction (SPE) There area number of parameters that affect SPE procedure such as

type of sorbent pH ionic strength sample and desorptionvolumes and wash step To optimize these parameters itused Milli-Q water spiked with a solution of fluorescenceoestrogens (estriol 17120573-estradiol and 17120572-ethinylestradiol)to obtain a final concentration of 250120583gsdotLminus1

The first parameter to optimize is the choice of sorbentsince it controls the selectivity affinity and capacity overanalytes In this study the SPE cartridges used were OASISHLB SepPak C

18(both from Waters Madrid Spain) and

BondElut ENV (fromAgilent Madrid Spain) Keeping otherparameters fixed (ionic strength of 0 sample volume of100mL) the cartridges were studied at three different pHs(5 8 and 11) From the results obtained it can be observedthat the better signals are found for SepPak C

18cartridge

(Figure 1)After choosing the optimum cartridge we used an initial

experimental design of 23 to study the influence of pH ionic

4 Journal of Analytical Methods in Chemistry

Table 2 Mass spectrometer parameters for the determination of target analytes

Compound Precursor ion(mz)

Capillary voltage(Ion mode)

Quantification ionmz(collision potential V)

Quantification ionmz(collision potential V)

E3 2872 minus65V (ESI minus) 1710 (37) 1452 (39)E2 2712 minus65V (ESI minus) 1451 (40) 1831 (31)EE 2952 minus60V (ESI minus) 1450 (37) 1589 (33)E1 2692 minus65V (ESI minus) 1450 (36) 1430 (48)DES 2671 minus50V (ESI minus) 2371 (29) 2511 (25)TES 2892 38V (ESI +) 1870 (18) 1040 (21)MGA 3855 30V (ESI +) 2673 (15) 2242 (30)NOR 3132 38V (ESI +) 1090 (26) 2451 (18)

0

500

1000

1500

2000

2500

E3 E2 EE

Peak

area

Cartridge optimizationOASIS HLB pH = 5

OASIS HLB pH = 8

OASIS HLB pH = 11SepPak C18 pH = 5

SepPak C18 pH = 8

SepPak C18 pH = 11BondElut ENV pH = 5

BondElut ENV pH = 8

BondElut ENV pH =11

Figure 1 Optimization of SPE cartridges

strength and sample volume over extraction process Theexperimental design was obtained using Statgraphics Plussoftware 51 and the statistics study was done with IBM SPSSStatistics 19 We assessed two levels and three parameters pH(3 and 8) ionic strength (0 and 30 of NaCl) and samplevolume (50 and 250mL) to obtain the influence of eachparameter and the variable correlation to each other In thisstudy it is observed that the ionic strength and sample volumehad the major influence on the recoveries of the analytesFor that a 32 factorial design to optimize these two variablesat three levels per parameter (0 15 and 30 of NaCl forionic strength and 50 100 y 250mL for sample volume) wasused Figure 2 shows the response surface obtained for theestriol and 17120572-ethinylestradiol The results obtained showedthat an increment of the ionic strength did not producean increase in the response area of the compound and theoptimum volume was 250mL Because of that a solutionwithout salt addition and 250mL of sample volume waschosen Finally the desorption volume (1mLofmethanol and2mL of methanol in one and two steps) and wash-step (5mL

ofMilli-Q water and 5mL ofMilli-Q water with 5 and 10 ofmethanol vv) were assayed to complete the optimization ofthe SPE process The optimum values were 2mL of methanolin one step and 5mL of Milli-Q water without methanolrespectively

In accordance with the obtained results the optimumconditions for SPE procedure were SepPak C

18cartridge

250mL of sample at pH = 8 and 0 of NaCl desorptionwith 2mL of methanol in one step and wash step with5mL of Milli-Q water In these conditions we achieved apreconcentration factor of 125 In Figure 3 a chromatogramwith the optimum conditions is shown where the peaksof all compounds in their corresponding transitions can beobserved

32 Analytical Parameters Because of the SPE optimizationthat was done only with fluorescent compounds (estriol 17120573-estradiol and 17120572-ethinylestradiol) it was necessary to studythe recoveries of all the hormonal compounds using theoptimized SPE-UHPLC-MSMSmethod All the compoundsunder study showed good recoveries over 73 except thediethylstilbestrol with a recovery of 507

A calibration curve was used for the quantification ofthe analytes by diluting the stock solution of each analyteinto the samples to concentrations ranging between 1 and100 120583gsdotLminus1 Analysis was conducted by UHPLC-MSMS andlinear calibration plots for each analyte (1199032 gt 099) wereobtained based on their chromatographic peak areas

The limit of detection (LOD) and the limit of quantifi-cation (LOQ) for each compound were calculated from thesignal-to-noise ratio of each individual peak The LOD wasdefined as the lowest concentration that gave a signal-to-noiseratio that was greater than 3 The LOQ was defined as thelowest concentration that gave a signal to noise ratio that wasgreater than 10The LODs ranged from015 to 935 ngsdotLminus1 andthe LOQs ranged from 049 to 3118 ngsdotLminus1

The performance and reliability of the process werestudied by determining the repeatability of the quantificationresults for all target analytes under the described conditionsusing six samples (119899 = 6) The relative standard deviations(RSDs) were lower than 84 in all cases indicating a

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 4: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Copyright copy 2013 Hindawi Publishing Corporation All rights reserved

This is a special issue published in ldquoJournal of Analytical Methods in Chemistryrdquo All articles are open access articles distributed underthe Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium providedthe original work is properly cited

Editorial Board

M Abdel-Rehim SwedenH Y Aboul Enein EgyptSilvana Andreescu USAA N Anthemidis GreeceA N Araujo PortugalR W Arndt SwitzerlandAna Cristi B Dias BrazilPierangelo Bonini ItalyArthur C Brown USAAntony C Calokerinos GreeceRicardo J Cassella BrazilXin-Sheng Chai ChinaO Chailapakul ThailandXingguo Chen ChinaC Collombel FranceW T Corns UKMiguel de la Guardia SpainIvonne Delgadillo PortugalE Dellacassa UruguayCevdet Demir TurkeyM Bonner Denton USAGregory W Diachenko USAM E Diaz-Garcia SpainDieter M Drexler USAJianxiu Du ChinaJenny Emneus DenmarkG Eppe BelgiumJosep Esteve-Romero SpainO Fatibello-Filho BrazilPaul S Francis AustraliaJuan F Garcia-Reyes SpainC Georgiou GreeceKate Grudpan ThailandR Haeckel Germany

Arafa I Hamed EgyptKaroly Heberger HungaryBernd Hitzmann GermanyChih-Ching Huang TaiwanI Isildak TurkeyJaroon Jakmunee ThailandXiue Jiang ChinaSelhan Karagoz TurkeyHiroyuki Kataoka JapanSkip Kingston USAChristos Kontoyannis GreeceR Kowalski PolandAnnamalai S Kumar IndiaIlkeun Lee USAJoe Liscouski USAEulogio J Llorent-Martinez SpainMercedes G Lopez MexicoMiren Lopez de Alda SpainLarisa Lvova ItalyJos Carlos Marques PortugalChristophe A Marquette FranceJean Louis Marty FranceSomenath Mitra USASerban C Moldoveanu USAMaria B Montenegro PortugalG A Nagana Gowda USAMilka Neshkova BulgariaB Nikolova-Damyanova BulgariaSune Nygaard DenmarkC K OrdquoSullivan SpainGangfeng Ouyang ChinaSibel A Ozkan TurkeyVeronica Pino SpainKrystyna Pyrzynska Poland

Jose B Quintana SpainMohammad A Rashid BangladeshD P S Rathore IndiaPablo Richter ChileFabio R P Rocha BrazilErwin Rosenberg AustriaGiuseppe Ruberto ItalyAntonio R Medina SpainBradley B Schneider CanadaGuoyue Shi ChinaJesus S Gandara SpainHana Sklenarova Czech RepublicN H Snow USAP B Stockwell UKF O Suliman OmanIt-Koon Tan SingaporeD G Themelis GreeceNilgun Tokman TurkeyNelson Torto South AfricaMarek Trojanowicz PolandParis Tzanavaras GreeceBengi Uslu TurkeyKrishna K Verma IndiaAdam Voelkel PolandFang Wang USAHai-Long Wu ChinaHui-Fen Wu TaiwanQingli Wu USAMengxia Xie ChinaRongda Xu USAXiu-Ping Yan ChinaLu Yang CanadaC Yin China

Contents

Analysis and Fate of Emerging Pollutants during Water Treatment Fei Qi Guang-Guo Ying Kaimin ShihJolanta Kumirska Elif Pehlivanoglu-Mantas and Xiaojun LuoVolume 2013 Article ID 256956 1 page

Occurrence and Removal Characteristics of Phthalate Esters from Typical Water Sources in NortheastChina Yu Liu Zhonglin Chen and Jimin ShenVolume 2013 Article ID 419349 8 pages

Simultaneous Determination of Hormonal Residues in Treated Waters Using Ultrahigh PerformanceLiquid Chromatography-Tandem Mass Spectrometry Rayco Guedes-Alonso Zoraida Sosa-Ferreraand Jose Juan Santana-RodrıguezVolume 2013 Article ID 210653 8 pages

Removal Efficiency and Mechanism of Sulfamethoxazole in Aqueous Solution by Bioflocculant MFXJie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei WeiVolume 2013 Article ID 568614 8 pages

Pyrite Passivation by Triethylenetetramine An Electrochemical Study Yun Liu Zhi Dang Yin Xuand Tianyuan XuVolume 2013 Article ID 387124 8 pages

A Green Preconcentration Method for Determination of Cobalt and Lead in Fresh Surface and WasteWater Samples Prior to Flame Atomic Absorption Spectrometry Naeemullah Tasneem Gul KaziFaheem Shah Hassan Imran Afridi Sumaira Khan Sadaf Sadia Arian and Kapil Dev BrahmanVolume 2012 Article ID 713862 8 pages

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 256956 1 pagehttpdxdoiorg1011552013256956

EditorialAnalysis and Fate of Emerging Pollutants duringWater Treatment

Fei Qi1 Guang-Guo Ying2 Kaimin Shih3 Jolanta Kumirska4

Elif Pehlivanoglu-Mantas5 and Xiaojun Luo2

1 Beijing Key Lab for Source Control Technology of Water Pollution College of Environmental Science and EngineeringBeijing Forestry University No 35 Qinghua East Road Beijing 100083 China

2 State Key Laboratory of Organic Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of SciencesGuangzhou 510640 China

3Department of Civil Engineering The University of Hong Kong Pokfulam Road Hong Kong4Department of Environmental Analysis Faculty of Chemistry University of Gdansk Sobieskiego 1819 80-952 Gdansk Poland5 Environmental Engineering Department Istanbul Technical University Ayazaga Campus Maslak 34469 Istanbul Turkey

Correspondence should be addressed to Fei Qi qifeibjfueducn

Received 23 April 2013 Accepted 23 April 2013

Copyright copy 2013 Fei Qi et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Emerging pollutants defined as compounds that are notcurrently covered by existing water-quality regulations allover the world have not been studied widely before and arethought to be potential threats to environmental ecosystemsand human health This special issue compiles 5 excitingpapers which are very meticulously performed researches

Generally emerging pollutants encompass a diversegroup of compounds including pharmaceuticals drugs ofabuse personal-care products (PCPs) steroids and hor-mones surfactants perfluorinated compounds (PFCs) flameretardants industrial additives and agents gasoline additivesnew disinfection byproducts (DBPs) nanomaterials and thetoxic minerals

The analysis methods occurrence and fate of hormonaland endocrine disruptors compounds (EDCs) were dis-cussed in two papers of this special issue R Guedes-Alonsoet al determine the hormonal residues in treated water byultrahigh performance liquid chromatography-tandem massspectrometry (UPLC-MS) and evaluate the efficiency ofthe conventional wastewater treatment for the removal ofhormonal compounds Moreover Y Liu et al study anotherkinds of PPCPs named as phthalate esters that is typicalkind of EDCs The occurrence in a surface water and theremoval efficiency in a traditional drinking water treatmentpalnt are studied According to results of the two papers

the occurrence and fate of hormonal and EDCs in water orwastewater treatment are very clear

J Xing et al report a new wastewater treatment technol-ogy bioflocculation for the removal of sulfamethoxazole thatis a typical pharmaceutical in wastewater The performanceand the reaction mechanism of the biodegradation of sul-famethoxazole by the bioflocculation are discussed in depthMoreover the optimum reaction condition is obtained

The heavy metal and toxic mineral are also importantpollutants in the environment especially in the mining areaTwo papers of this issue are focused on this K Naeemul-lah et al report a green preconcentration method for thedetermination of cobalt and lead in water Y Liu et al do anovel research on the electrochemical reaction of pyrite as asimulation of the natural environmental

By compiling this special issue we hope to enrich ourreaders and researchers on the analysis and fate of emergingpollutants during water treatment

Fei QiGuang-Guo Ying

Kaimin ShihJolanta Kumirska

Elif Pehlivanoglu-MantasXiaojun Luo

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 419349 8 pageshttpdxdoiorg1011552013419349

Research ArticleOccurrence and Removal Characteristics of Phthalate Estersfrom Typical Water Sources in Northeast China

Yu Liu Zhonglin Chen and Jimin Shen

State Key Laboratory of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Jimin Shen shenjiminhiteducn

Received 21 December 2012 Accepted 3 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Yu Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The presence of phthalate esters (PAEs) in the environment has gained a considerable attention due to their potential impactson public health This study reports the first data on the occurrence of 15 PAEs in the water near the Mopanshan Reservoirmdashthenew and important water source of Harbin city in Northeast China As drinking water is a major source for human exposureto PAEs the fate of target PAEs in the two waterworks (Mopanshan Waterworks and Seven Waterworks) was also analyzed Theresults demonstrated that the total concentrations of 15 PAEs in the water near the Mopanshan Reservoir were relatively moderateranging from 3558 to 92265 ngL with the mean value of 29431 ngL DBP and DEHP dominated the PAE concentrations whichranged from 525 to 44982 ngL and 1289 to 65709 ngL respectivelyThe occurrence and concentrations of these compoundswereheavily spatially dependent Meanwhile the results on the waterworks samples suggested no significant differences in PAE levelswith the input of the raw waters Without effective and stable removal of PAEs after the conventional drinking water treatment inthe waterworks (258 to 765) the risks posed by PAEs through drinking water ingestion were still existing which should bepaid special attention to the source control in theMopanshan Reservoir and some advanced treatment processes for drinking watersupplies

1 Introduction

Phthalate acid esters a class of chemical compounds mainlyused as plasticizers for polyvinyl chloride (PVC) or to alesser extent other resins in different industrial activities areubiquitous in the environment and have evoked interest inthe past decade due to endocrine disrupting effects and theirpotential impacts on public health [1ndash3]

Worldwide production of PAEs is approximately 6 mil-lion tons per year [4] As PAEs are not chemically boundto the polymeric matrix in soft plastics they can enter theenvironment by losses during manufacturing processes andby leaching or evaporating from final products [5]Thereforethe occurrence and fate of specific PAEs in natural waterenvironments have been observed and also there are a lot ofconsiderable controversies with respect to the safety of PAEsin water [5ndash10]

Six PAE compounds including dimethyl (DMP) diethyl(DEP) dibutyl (DBP) butylbenzyl (BBP) di(2-ethylhexyl)

(DEHP) and di-n-octyl phthalate (DNOP) are classifiedas priority pollutants by the US Environmental ProtectionAgency (EPA) Though the toxicity of PAEs to humans hasnot been well documented for some years the Ministry ofEnvironmental Protection in China has regulated phthalatesas environmental pollutants In addition the standard inChina concerning analytical controls on drinkingwaters doesnot specifically identify any PAEs as organic pollutant indexesto be determined by the new drinking water standard in 2007(Standard for drinking water quality GB5749-2006) whichwas forced to be monitored for the drinking water supplies in2012 Consequently official data about the presence of thesepollutants in the aquatic environment of some cities are notavailable

Harbin the capital of Heilongjiang Province is a typicallyold industrial base and economically developed city with apopulation of over 3million inNortheast China As the newlyenabledwater source forHarbin cityMopanshanwaterworkssupply the whole city with drinking water through long

2 Journal of Analytical Methods in Chemistry

China

HarbinMopanshan

Reservoir

LongfengshanReservoir

Figure 1 Spatial distribution of the 16 sampling sites near the Mopanshan Reservoir in Northeast China

distance transfer from the Mopanshan Reservoir To theauthorsrsquo knowledge the occurrence and fate of PAEs in thewater near this area and its relative waterworks have notpreviously been examined

The objectives of this study were (i) to determine theoccurrence of PAEs and clarify the fate and distribution ofthe pollutants in the water source (ii) to examine the twowaterworks where traditional drinking water treatment stepwas evaluated on the PAEs removal efficiencies and (iii) toevaluate the potential for adverse effects of PAEs on humanhealth Therefore the investigation of PAEs in the water canprovide a valuable record of contamination in Harbin city

2 Materials and Methods

21 Chemical Fifteen PAEs standard mixture includingdimethyl phthalate diethyl phthalate diisobutyl phthalatedi-n-butyl phthalate di(4-methyl-2-pentyl) phthalate di(2-ethoxyethyl) phthalate di-n-amyl phthalate di-n-hexylphthalate butyl benzyl phthalate di(hexyl-2-ethylhexyl)phthalate di(2-n-butoxyethyl) phthalate dicyclohexyl phthal-ate di(2-ethylhexyl) phthalate di-n-nonyl phthalate di-n-octylphthalate at 1000 120583gmL each and surrogate standardsconsisting of diisophenyl phthalate di-n-phenyl phthal-ate and di-n-benzyl phthalate in a mixture solution of500120583gmL each were supplied by AccuStandard Inc Asthe internal standard benzyl benzoate was also purchasedfrom AccuStandard Inc All solvents (acetone hexane anddichloromethane) used were HPLC-grade and were pur-chased from J T Baker Co (USA) Anhydrous sodiumsulfate (Tianjin Chengguang Chemical Reagent Co China)was cleaned at 600∘C for 6 h and then kept in a desiccatorbefore use

22 Sample Collection and Preparation Harbin the capitalof Heilongjiang province in China imports nearly all of itsdrinking water from two sources the Mopanshan Reservoir

Raw water Coagulation sedimentation Filtration Tank

Sampling site Sampling site

Figure 2 Schematic diagram of the waterworks

(long-distance transport project) and the Songhua River (oldwater source)

Water samples from the Mopanshan Reservoir andMopanshan waterwork were collected in 2008 The locationsof the sampling sites near the Mopanshan Reservoir are pre-sented in Figure 1 as a comparison sampling from anotherHarbin water supplymdashSeven waterworks with water sourcefrom the SonghuaRiverwas performed in 2011 In eachwater-works with considering the hydraulic retention time threesets of raw water samples (influent) were taken and thenthe final finished waters (effluent) after the whole treatmentprocess were carried out for the collectionsThe flow diagramof the waterworks is shown in Figure 2

Samples were collected using 20 L glass jars from 05mbelow the water surface During the whole sampling processthe global position system was used to locate the samplingstations (details in Table 1) All samples were transferred tothe laboratory directly after sampling and stored at 4∘C priorto extraction within 2 d

Water samples were filtered under vacuum through glassfiber filters (07 120583mpore sizes) Prior to extraction each sam-ple was spiked with surrogate standards The water sampleswere extracted based on a classical liquid phase extractionmethod (USEPA method 8061) with slight modificationsBriefly 1 L of water samples was placed in a separating funneland extracted by means of mechanical shaking with 150mLdichloromethane and then with filtration on sodium sulfate(about 20 g) the organic extracts were concentrated usinga rotary evaporator The exchange of solvent was done byreplacing dichloromethane with hexane Finally they were

Journal of Analytical Methods in Chemistry 3

Table 1 Detailed descriptions of the sampling locations

Number Sampling site Name Latitude Longitude1 Lalin Jinsan Bridge Mangniu River E127∘0210158405310158401015840 N45∘510158404510158401015840

2 Xingsheng Town Gaojiatun Lalin River E127∘0610158401110158401015840 N44∘5110158405710158401015840

3 Dujia Town Shuguang Lalin River E127∘1010158404410158401015840 N44∘4810158404110158401015840

4 Shanhe Town Taipingchuan Lalin River E127∘1810158403610158401015840 N44∘4310158405010158401015840

5 Xiaoyang Town Qichuankou Lalin River E127∘2310158405410158401015840 N44∘3910158404610158401015840

6 Shahezi Town Mopanshan Reservoir E127∘3810158405910158401015840 N44∘2410158401710158401015840

7 Shahezi Town Gali Lalin River E127∘3510158401710158401015840 N44∘3110158405610158401015840

8 Chonghe Town Changcuizi Mangniu River E127∘4610158403610158401015840 N44∘3510158404610158401015840

9 Chonghe Town Xingguo Mangniu River E127∘3510158401710158401015840 N44∘3110158405710158401015840

10 Longfeng Town Mangniu River E127∘3510158401910158401015840 N44∘4310158404810158401015840

11 Changpu Town Zhonghua Mangniu River E127∘1610158403010158401015840 N45∘110158404210158401015840

12 Erhe Town Shuanghe Mangniu River E127∘1810158403210158401015840 N45∘410158402810158401015840

13 Zhiguang Town Songjiajie Mangniu River E127∘341015840310158401015840 N45∘110158402010158401015840

14 Zhiguang Town Wuxing Mangniu River E127∘2910158402010158401015840 N45∘010158404310158401015840

15 Changpu Town Xingzhuang Mangniu River E127∘1010158404210158401015840 N45∘410158403610158401015840

16 Yingchang Town Xingguang Lalin River E126∘551015840810158401015840 N45∘91015840010158401015840

reduced to 05mL under gentle nitrogen flow The internalstandard was added to the sample prior to instrumentalanalysis

23 Chemical Analysis The extracted compounds weredetermined by gas chromatography coupled to mass spec-trometer analysis as described in other publications [1112] Briefly extracted samples were injected into an Agilent6890 Series GC equipped with a DB-35MS capillary column(Agilent 30m times 025mm id 025120583m film thickness) andan Agilent 5973 MS detector operating in the selective ionmonitoring mode The column temperature was initially setat 70∘C for 1min then ramped at 10∘Cmin to 300∘C andheld constant for 10min The transfer line and the ion sourcetemperature were maintained at 280 and 250∘C respectivelyHelium was used as the carrier gas at a flow rate of 1mLminThe extracts (20 120583L) were injected in splitless mode with aninlet temperature of 300∘C

24 Quality Assurance and Quality Control All glasswarewas properly cleaned with acetone and dichloromethanebefore use Laboratory reagent and instrumental blanks wereanalyzed with each batch of samples to check for possiblecontamination and interferences Only small levels of PAEswere found in procedural blanks in some batches andthe background subtraction was appropriately performed inthe quantification of concentration in the water samplesCalibration curves were obtained from at least 3 replicateanalyses of each standard solution The surrogate standardswere added to all the samples to monitor matrix effectsRecoveries of PAEs ranged from 62 to 112 in the spikedwater and the surrogate recoveries were 751 plusmn 127 fordiisophenyl phthalate 723 plusmn 143 for di-n-phenyl phtha-late and 1026 plusmn 104 for di-n-benzyl phthalate in thewater samples The determination limits ranged from 6 to30 ngL A midpoint calibration check standard was injected

as a check for instrumental drift in sensitivity after every10 samples and a pure solvent (methanol) was injected as acheck for carryover of PAEs from sample to sample All theconcentrations were not corrected for the recoveries of thesurrogate standards

3 Results and Discussion

31 PAEs in Water Source The PAEs in the waters fromthe sampling sites near the Mopanshan Reservoir wereinvestigated and the results are presented in Table 2 Thesum15

PAEs concentrations ranged from 3558 to 92265 ngLwith the geometric mean value of 29431 ngL Among the15 PAEs detected in the waters DIBP DBP and DEHP weremeasured in all the samples with the average concentrationsbeing 1966 8014 and 17741 ngL respectively The threePAE congeners are important and popular addictives inmany industrial products including flexible PVC materialsand household products suggesting the main source of PAEcontaminants in the water [13] The correlations of the con-centration of DEHP DBP and DIBP with the concentrationsof total PAEs in the water samples are shown in Figure 3and a relatively significant correlation between sum

15

PAEs andDEHP concentration was found suggesting the importantpart played by DEHP in total concentrations of PAEs inthe water bodies near the Mopanshan Reservoir In otherwords the contribution of DEHP to total PAEs was higherthan that of other PAE congeners in the water samples Inaddition DMP DEP and DNOP with the mean value of140 284 and 541 ngL respectively only detected at somesampling sites and have also attracted much attention asthe priority pollutants by the China National EnvironmentalMonitoring Center On the contrary the concentrations of6 PAEs (DMEP BMPP BBP DBEP DCHP and DNP) werebelow detection limits in all the water samples near theMopanshan Reservoir which is easily explained in terms ofmuch lower quantities of present use in China

4 Journal of Analytical Methods in Chemistry

0 2000 4000 6000 80000

2000

4000

6000

Con

cent

ratio

ns (n

gL)

DEHP

119903 = 0885 119875 lt 001

sum15PAEs (ngL)

(a)

0 2000 4000 6000 80000

2000

4000

Con

cent

ratio

ns (n

gL)

sum15PAEs (ngL)

DBP

119903 = 0812 119875 lt 001

(b)

1000

500

0

0 2000 4000 6000 8000sum15PAEs (ngL)

DIBP

Con

cent

ratio

ns (n

gL)

119903 = 0724 119875 lt 001

(c)

Figure 3 Correlations of the concentration of the major PAEs (DEHP DBP and DIBP) with the concentrations of total PAEs in the watersamples

Table 2 Concentrations of 15 PAEs in water samples near the Mopanshan Reservoir

PAEs Abbreviation Water (ngL)Range Mean Frequency

Dimethyl phthalate DMP ndndash424 140 816Diethyl phthalate DEP ndndash550 284 1516Diisobutyl phthalate DIBP 400ndash6588 1966 1616Dibutyl phthalate DBP 525ndash44982 8014 1616bis(2-methoxyethyl)phthalate DMEP nd nd 016bis(4-methyl-2-pentyl)phthalate BMPP nd nd 016bis(2-ethoxyethyl)phthalate DEEP ndndash546 128 516Dipentyl phthalate DPP ndndash925 455 1016Dihexyl phthalate DHXP ndndash651 162 516Benzyl butyl phthalate BBP nd nd 016bis(2-n-butoxyethyl)phthalate DBEP nd nd 016Dicyclohexyl phthalate DCHP nd nd 016bis(2-ethylhexyl)phthalate DEHP 1289ndash65709 17741 1616Di-n-octyl phthalate DNOP ndndash4482 541 516Dinonyl phthalate DNP nd nd 016sum15

PAEs 3558ndash92265 29431 mdash

The distribution of 15 PAEs (sum15

PAEs) studied and6 US EPA priority PAEs (sum

6

PAEs including DMP DEPDIBP DBP DEHP and DNOP) in the waters from differentsampling sites are shown in Figure 4 There was an obviousvariation in the total sum

15

PAEs concentrations in water sam-ples near the Mopanshan Reservoir the concentrations ofsum6

PAEs from the same sampling sites varied from 2690 to90860 ngL with an average of 28686 ngL the distributionspectra of which observed for all the sampling sites weresimilar tosum

15

PAEsThe highest levels of PAEs contaminationwere seen on the sampling site 3 followed by some relativelyheavily polluted sites (site 16 13 9 10 and 11) indicating thatthese sites served as important PAE sources and the spatialdistribution of PAEs was site specific The levels in the watersexamined varied over a wide range especially in theMangniu

River near theMopanshan Reservoir (in some case overmorethan one order of magnitude) In general it should be notedthat there might be a relation of PAEs levels with the input oflocal waste such as sewage water food packaging and scrapmaterial near the sampling point which were found duringthe sampling period

32 PAE Congener Profiles in the Water Different PAE pat-terns may indicate different sources of PAEs Measurementof the individual PAE composition is helpful to track thecontaminant source and demonstrate the transport and fateof these compounds in water [11] The relative contributionsof the 9 detectable PAE congeners to thesum

15

PAEs concentra-tions in the water are presented in Figure 5 It is clear thatDEHP was the most abundant in the water samples with

Journal of Analytical Methods in Chemistry 5

0

500

1000

1500

4000

6000

8000

10000

Con

cent

ratio

ns (n

gL)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

sum15PAEssum6PAEs

Figure 4 Spatial distributions of the 16 sampling sites near theMopanshan Reservoir

the exception of site 2 3 and 11 contributions ranging from331 to 963 followed byDBP ranging from 21 to 363The results are consistent with the above data for overallanalysis that DBP and DEHP are the dominant componentsof the PAEs distribution pattern in each sampling site whichreflected the different pattern of plastic contaminant inputduring the sampling period Similarly DIBP and DBP areused in epoxy resins or special adhesive formulations withthe different proportions of these two PAE congeners whichwere also the important indicator of the information pollutedby PAEs for the sampling locations Although the limitedsample number draws only limited conclusions there is stillreason to note that a leaching from the plastic materials intothe runoff water is possible and that water runoff from thecontaminated water is a burden pathway from differentsources of PAEs [14]

33 Comparison with Other Water Bodies Comparison withthe total PAEs concentrations is nevertheless very limited dueto the different analysis compounds However the individualPAE namely DBP and DEHP is by far the most abundantin other researches and it is possible to make a camparisonwith our findings In this case the results of DBP and DEHPconcentrations published in literatures for kinds of waterbodies are presented together in Table 3

The DEHP and DBP concentrations of the present studyshowed to some extent lower concentration levels than thosereported in the other water bodies in China In comparisonthe results were comparable or similar to those from theexaminations described in other foreign countries For exam-ple as shown in Table 3 the DEHP concentrations were sim-ilar to the surface waters from the Netherlands and Italydescribed in the literature Meanwhile these concentrationsin this study were quite lower than the Yangtze River andSecond Songhua River in China

0

20

40

60

80

100

DEEP DPP DHXP DEHP DNOP DBP

DIBP DEP DMP

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

Com

posit

ion

()

Figure 5 PAE composition of thewater samples in 16 sampling sites

In conclusion as compared to the results of other studiesthe waters near the Mopanshan Reservoir were moderatelypolluted by PAEs Therefore there is a definite need to set upa properly planned and systematic approach to water controlnear the Mopanshan Reservoir

34 PAE Levels in the Waterworks The Mopanshan Water-works (MPSW) equipped essentially with the water sourceof the Mopanshan Reservoir has been investigated in orderto assess the fate of the PAEs during the drinking watertreatment process For comparison a sampling campaign forthe determination of PAEs levels in the Seven Waterworks(SW waterworks with the old water source of the SonghuaRiver) was carried out Both waterworks operate coagulationsedimentation and followed by filtration treatment processwhich are typical traditional drinking water treatment

The measured concentrations in the raw and finishedwater of the two investigated waterworks are shown inFigure 6 Six out of fifteen PAEs were detected in the fin-ished water from the two waterworks The detected PAEswere DMP DEP DIBP DBP DEHP and DNOP and theother investigated phthalates are of minor importance withconcentrations all below the limit of detection As showin Figure 6 the measured concentrations of the analyzedPAEs in the finished water of the two waterworks variedstronglyThemost important compound in the finishedwaterwas DEHP with the mean concentration of 34737 and40592 ngL for the MPSW and SW respectively suggestingthe highest relative composition of total PAE concentrationsin the drinking water

For the raw water from the different water sources DMPand DIBP concentrations in the MPSW were much lowerthan the ones in the SW and the concentrations of DEPDBP DEHP andDEHPwere relatively comparable in the two

6 Journal of Analytical Methods in Chemistry

Table 3 Comparison of the concentrations of DEHP and DBP in the water bodies (ngL)

Location DEHP DBP ReferenceRange Median Mean Range Median Mean

Surface water Germany 330ndash97800 2270 mdash 120ndash8800 500 mdash [14]Surface water the Netherlands ndndash5000 320 mdash 66ndash3100 250 mdash [15]Seine River estuary France 160ndash314 mdash mdash 67ndash319 mdash mdash [16]Tama River Japan 13ndash3600 mdash mdash 8ndash540 mdash mdash [17]Velino River Italy ndndash6400 mdash mdash ndndash44300 mdash mdash [2]Surface water Taiwan ndndash18500 mdash 9300 1000ndash13500 mdash 4900 [18]Surface water Jiangsu China 556ndash156707 mdash mdash 16ndash58575 mdash mdash [19]Yangtze River mainstream China 3900ndash54730 mdash mdash ndndash35650 mdash mdash [20]Middle and lower Yellow River China 347ndash31800 mdash mdash ndndash26000 mdash mdash [21]Second Songhua River China ndndash1752650 370020 mdash ndndash5616800 mdash 717240 [22]Urban lakes Guangzhou China 87ndash630 170 240 940ndash3600 1990 2030 [11]Xiangjiang River China 620ndash15230 mdash mdash mdash mdash mdash [23]This study 1289ndash65709 6710 17741 525ndash44982 1103 8014

0

500

1000

100001200014000

0

20

40

60

80

100

Raw waterFinished waterRemoval

Rem

oval

()

Con

cent

ratio

ns (n

gL)

DMP DEP DIBP DBP DEHP DNOP

(a)

Raw waterFinished waterRemoval

0

500

1000

1500

2000

100001200014000

0

20

40

60

80

100C

once

ntra

tions

(ng

L)

Rem

oval

()

DMP DEP DIBP DBP DEHP DNOP

(b)

Figure 6 PAEs detected in the water samples from the MPSW (a) and SW (b)

waterworks The removal of PAEs by these two waterworksranged from 258 to 765 which varied significantly with-out stable removal efficienciesThe lower removal efficienciesfor DMP and DNOP were observed in the SW with theremoval less than 30 For both the waterworks no soundremoval efficiencies were obtained for the PAEs indicatingthat the traditional drinking water treatment cannot showgood performance to eliminate these micro pollutants whichhas nothing to do with the type of the water source

Traditional drinking water treatment focuses on dealingwith the particles and colloids in terms of physical processesMany studies of the environmental fates of PAEs have demon-strated that oxidation or microbial action is the principalmechanism for their removal in the aquatic systems [24ndash26]Therefore the treatment process should be the combinationswith the key techniques for removing PAEs from the waterOn the other hand since the removal efficiencies of PAEs by

these advance drinking water treatments in waterworks hasnot been systematically studied to date further research inthis direction would seem to be required

35 Exposure Assessment of PAEs in Water To evaluate thepotential and adverse effects of PAEs quality guidelines forsurface water and drinking water standard were used Theresults indicated that the mean concentrations of DBP andDEHP at levels were well below the reference doses (RfD)regarded as unsafe by the EPA for the surface water Thelevels were not also above the RfD recommended by China(Environmental Quality Standard for SurfaceWater of ChinaGB3838-2002) On the other hand the amounts of DEHPpresent in public water supplies should be lower than thedrinkingwater standard (0006mgL for EPA and 0008mgLfor China) According to the results the concentrations of

Journal of Analytical Methods in Chemistry 7

DEHP in drinkingwater samples from theMPSWwere lowerthan the limited value

PAEs are also considered to be endocrine disruptingchemicals (EDCs) whose effects may not appear until long-term exposure According to the results PAEs were detectedin the drinking water constantly ingested in daily life indi-cating that drinking water is an important source of humanexposure to PAEs contaminants Assuming a daily waterconsumption rate of 2 L and an average body weight of 60 kgfor adults the average daily intake of DEHP DBP and DIBPby way of drinking water from MPSW was calculated to be1158 1352 and 81 ngkgd respectively In comparison thevalues of SW with the water source of the Songhua Riverwere relatively higher with the calculated results of 1353140 and 155 ngkgd for DEHP DBP and DIBP respectivelyIn this study the estimated daily intake levels of DEHPfrom the drinking water were quite lower than the RfDof 20000 ngkgd released by the EPA However some ofPAEs are partly metabolised in the organism and futureexperiments should be focused on determining the potentialeffects of the metabolites [27]

Currently treated water from the Songhua River is fornonpotable uses and MPSW is the exclusive waterworks runfor the water supply of Harbin city However populationgrowth and drought cycle are limited by the availability of rawwater from theMopanshan Reservoir Tomeet the increasingdemand local and regional water authorities have begun acampaign of second water supply project from the SonghuaRiver again which needs the protection of the Songhua Riverand advanced water treatment for the source

4 Conclusions

This study provided the first detailed data on the contami-nation status of 15 PAEs in the water near the MopanshanReservoir The concentration range of 15 PAEs in the sampleswas from 3558 to 92265 ngL with the mean value of29431 ngL DEHP andDBPwere themain pollutants among15 PAEs accounting for the main watershed pollution Theoccurrence and distribution of PAEs from different samplingsites in the water source varied largely suggesting that thespatial distribution of PAEs was site specific In additionthe monitoring of PAEs in the waterworks also showed thatPAEs can be detected in the drinking water and certaintoxicological risks to drinking water consumers were foundThese results reported here contribute to an understandingof how PAE contaminants are distributed in the new watersource and the waterworks in Harbin city as well as forminga basis for further modeling risk assessment and selection ofdrinking water treatment technology

In conclusion the results implied that no urgent reme-diation measures were required with respect to PAEs in thewaters However the ecological and health effects of thesesubstances through drinkingwater at the relatively lower con-centrations still need further notice in light of their possiblebiological magnifications Therefore the long-term sourcecontrol in the water and adding advanced treatment processfor drinking water supplies should be given special attentionin this area

Acknowledgments

This work was supported by the National Natural ScienceFoundation of China (1077029) the Funds for CreativeResearch Groups of China (Grant no 51121062) the NationalNatural Science Foundation of China (51078105) and theOpen Project of the State Key Laboratory of Urban WaterResource and Environment Harbin Institute of Technology(no QA201019)

References

[1] M Nikonorow H Mazur and H Piekacz ldquoEffect of orallyadministered plasticizers and polyvinyl chloride stabilizers inthe ratrdquo Toxicology and Applied Pharmacology vol 26 no 2 pp253ndash259 1973

[2] M Vitali M Guidotti G Macilenti and C Cremisini ldquoPhtha-late esters in freshwaters asmarkers of contamination sourcesmdasha site study in ItalyrdquoEnvironment International vol 23 no 3 pp337ndash347 1997

[3] G Latini C de Felice G Presta et al ldquoIn utero exposure todi-(2-ethylhexyl)phthalate and duration of human pregnancyrdquoEnvironmental Health Perspectives vol 111 no 14 pp 1783ndash17852003

[4] C E Mackintosh J A Maldonado M G Ikonomou and F AP C Gobas ldquoSorption of phthalate esters and PCBs in a marineecosystemrdquo Environmental Science and Technology vol 40 no11 pp 3481ndash3488 2006

[5] M Clara G Windhofer W Hartl et al ldquoOccurrence of phtha-lates in surface runoff untreated and treated wastewater andfate during wastewater treatmentrdquo Chemosphere vol 78 no 9pp 1078ndash1084 2010

[6] M M Abdel Daiem J Rivera-Utrilla R Ocampo-Perez J DMendez-Dıaz andM Sanchez-Polo ldquoEnvironmental impact ofphthalic acid esters and their removal fromwater and sedimentsby different technologiesmdasha reviewrdquo Journal of EnvironmentalManagement vol 109 pp 164ndash178 2012

[7] L Chen Y Zhao L Li B Chen and Y Zhang ldquoExposureassessment of phthalates in non-occupational populations inChinardquo Science of the Total Environment vol 427-428 pp 60ndash69 2012

[8] M J Teil M Blanchard andM Chevreuil ldquoAtmospheric fate ofphthalate esters in an urban area (Paris-France)rdquo Science of theTotal Environment vol 354 no 2-3 pp 212ndash223 2006

[9] P Roslev K Vorkamp J Aarup K Frederiksen and P HNielsen ldquoDegradation of phthalate esters in an activated sludgewastewater treatment plantrdquo Water Research vol 41 no 5 pp969ndash976 2007

[10] J Gasperi S Garnaud V Rocher and R Moilleron ldquoPrioritypollutants in wastewater and combined sewer overflowrdquo Scienceof the Total Environment vol 407 no 1 pp 263ndash272 2008

[11] F Zeng K Cui Z Xie et al ldquoOccurrence of phthalate estersin water and sediment of urban lakes in a subtropical cityGuangzhou South Chinardquo Environment International vol 34no 3 pp 372ndash380 2008

[12] F Zeng K Cui Z Xie et al ldquoPhthalate esters (PAEs) emergingorganic contaminants in agricultural soils in peri-urban areasaround Guangzhou Chinardquo Environmental Pollution vol 156no 2 pp 425ndash434 2008

[13] G Wildbrett ldquoDiffusion of phthalic acid esters from PVC milktubingrdquo Environmental Health Perspectives vol 3 pp 29ndash351973

8 Journal of Analytical Methods in Chemistry

[14] H Fromme T Kuchler T Otto K Pilz J Muller and AWenzel ldquoOccurrence of phthalates and bisphenol A and F inthe environmentrdquoWater Research vol 36 no 6 pp 1429ndash14382002

[15] A D Vethaak J Lahr S M Schrap et al ldquoAn integrated assess-ment of estrogenic contamination and biological effects in theaquatic environment ofTheNetherlandsrdquoChemosphere vol 59no 4 pp 511ndash524 2005

[16] C Dargnat M Blanchard M Chevreuil andM J Teil ldquoOccur-rence of phthalate esters in the Seine River estuary (France)rdquoHydrological Processes vol 23 no 8 pp 1192ndash1201 2009

[17] T Suzuki K Yaguchi S Suzuki and T Suga ldquoMonitoring ofphthalic acid monoesters in river water by solid-phase extrac-tion and GC-MS determinationrdquo Environmental Science andTechnology vol 35 no 18 pp 3757ndash3763 2001

[18] S Y Yuan C Liu C S Liao and B V Chang ldquoOccurrenceand microbial degradation of phthalate esters in Taiwan riversedimentsrdquo Chemosphere vol 49 no 10 pp 1295ndash1299 2002

[19] B Li C Qu and J Bi ldquoIdentification of trace organic pollutantsin drinking water and the associated human health risks inJiangsu Province Chinardquo Bulletin of Environmental Contami-nation and Toxicology pp 1ndash5 2012

[20] F Wang X Xia and Y Sha ldquoDistribution of phthalic acidesters in Wuhan section of the Yangtze River Chinardquo Journalof Hazardous Materials vol 154 no 1ndash3 pp 317ndash324 2008

[21] Y J Sha X H Xia and X Q Xiao ldquoDistribution characters ofphthalic acid ester in the waters middle and lower reaches ofthe Yellow Riverrdquo China Environmental Science vol 26 no 1pp 120ndash124 2006

[22] J Lu L-B Hao C-Z Wang W Li R-J Bai and D YanldquoDistribution characteristics of phthalic acid esters in middleand lower reaches of no 2 Songhua Riverrdquo EnvironmentalScience amp Technology vol 12 article 014 2007

[23] X J Zhu and Y Y Qiu ldquoMeasuring the phthalates of xiangjiangriver using liquid-liquid extraction gas chromatographyrdquoAdvanced Materials Research vol 301 pp 752ndash755 2011

[24] B L Yuan X Z Li and N Graham ldquoAqueous oxida-tion of dimethyl phthalate in a Fe(VI)-TiO

2

-UV reaction sys-temrdquoWater Research vol 42 no 6-7 pp 1413ndash1420 2008

[25] Z Yunrui ZWanpeng L FudongW Jianbing and Y ShaoxialdquoCatalytic activity of RuAl2O3 for ozonation of dimethylphthalate in aqueous solutionrdquo Chemosphere vol 66 no 1 pp145ndash150 2007

[26] H N Gavala U Yenal and B K Ahring ldquoThermal andenzymatic pretreatment of sludge containing phthalate estersprior tomesophilic anaerobic digestionrdquoBiotechnology and Bio-engineering vol 85 no 5 pp 561ndash567 2004

[27] Y Guo Q Wu and K Kannan ldquoPhthalate metabolites in urinefrom China and implications for human exposuresrdquo Environ-ment International vol 37 no 5 pp 893ndash898 2011

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 210653 8 pageshttpdxdoiorg1011552013210653

Research ArticleSimultaneous Determination of Hormonal Residuesin Treated Waters Using Ultrahigh Performance LiquidChromatography-Tandem Mass Spectrometry

Rayco Guedes-Alonso Zoraida Sosa-Ferrera and Joseacute Juan Santana-Rodriacuteguez

Departamento de Quımica Universidad de Las Palmas de Gran Canaria 35017 Las Palmas de Gran Canaria Spain

Correspondence should be addressed to Jose Juan Santana-Rodrıguez jsantanadquiulpgces

Received 28 December 2012 Accepted 7 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Rayco Guedes-Alonso et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

In the last years hormone consumption has increased exponentially Because of that hormone compounds are considered emergingpollutants since several studies have determinted their presence in water influents and effluents of wastewater treatment plants(WWTPs) In this study a quantitative method for the simultaneous determination of oestrogens (estrone 17120573-estradiol estriol17120572-ethinylestradiol and diethylstilbestrol) androgens (testosterone) and progestogens (norgestrel andmegestrol acetate) has beendeveloped to determine these compounds in wastewater samples Due to the very low concentrations of target compounds in theenvironment a solid phase extraction procedure has been optimized and developed to extract and preconcentrate the analytesDetermination and quantification were performed by ultrahigh performance liquid chromatography-tandem mass spectrometry(UHPLC-MSMS) The method developed presents satisfactory limits of detection (between 015 and 935 ngsdotLminus1) good recoveries(between 73 and 90 for the most of compounds) and low relative standard deviations (under 84) Samples from influents andeffluents of two wastewater treatment plants of Gran Canaria (Spain) were analyzed using the proposed method finding severalhormones with concentrations ranged from 5 to 300 ngsdotLminus1

1 Introduction

In general it is supposed that more than 100000 differentchemical compounds can be introduced in the Environmentmany of them in very small quantity However a lot of thesecompounds are not included as pollutants in the legislationAlthough these compounds named emerging pollutants arenot regulated as pollutants they probably will be in the futurebecause of their potential negative effect in the ecosystem For20 years many articles have reported the presence of theseldquonew compoundsrdquo in wastewater [1 2]

The emerging pollutant origin is mainly anthropogenicconsidering that the majority of these compounds are bio-logically active substances that are synthesized to use themin agriculture industry and medicine The main source ofthese emerging pollutants is the residual urbanwaters and thewastewater treatment plants effluents because many of these

WWTPs are not designed or optimized to treat this kind ofcompounds [3]

Hormones are one of the most potent endocrine disrupt-ing compounds as well as are considered also as emergingpollutants Hormones can be differentiated in oestrogensandrogens and progestogens Some of them have limits intheir use but not a specific legislation [4]

The main characteristic of these pollutants is that it isnot necessary to remain in the environment to cause negativeeffects in view of the fact that their constant introduction init offsets their removal or degradation [5]

The steroid hormones help controlling the metabolisminflammations immunological functions water and salt bal-ance sexual development and the capacity of withstandingillnesses [6] The term steroid can be used for naturalhormones produced by the body as well as for artificiallyproduced medicines that increase the natural steroid effect

2 Journal of Analytical Methods in Chemistry

In the last 50 years the natural and synthetic hormoneworldwide consumption has grown as much as in humanmedicine as in cattle farming and they become the mostprescribed medicines [7]

A significant quantity of consumed oestrogens leaves theorganism through excretions For example 17120573-estradiol (E2)is oxidized rapidly becoming an estrone (E1) that can turninto estriol afterwards (E3) Besides the 17120572-ethinyl estradiol(EE) is excreted as conjugated [8]

With regard to emission sources in the first place arethe wastewater treatment plants (WWTPs) [9] and secon-darily cattle waste such as those leachates from dung anduncontrolled dumping [10] Several studies made in theWWTPs have reported that the treatment plants are capableof eliminating around 60 of hormones [11ndash13]

The identification of hormone residues in environmentis of special interest because knowledge of these compoundsis a requirement to take measures in order to regulate andminimize their environmental impact

However measurement of hormone residues is a verydifficult task not only due to the difficulty in measuringvery low concentration but also due to a very complexityof the samples Therefore use of mass spectrometer (MS)as detector coupled with chromatography techniques hasbecome a powerful method for the analysis of these typesof compounds at trace levels [14ndash17] Consequently LC-MSMS is the principally chosen technique One of the mainadvantages of LC-MSMS is its ability to analyze hormoneswithout derivatization (necessary in GC) or the need ofhydrolyze the conjugated form

Due to low level concentration of these compounds inenvironmental water it is necessary to apply an extractionand preconcentration method prior to LC analysis The mostused technique of extraction and preconcentration methodfor liquid samples is the solid phase extraction (SPE) [18ndash20]

The objective of this study is to develop a rapid and simpleprocedure of extraction preconcentration and determina-tion of four steroid oestrogens (estrone (E1) 17120573-estradiol(E2) estriol (E3) and 17120572-ethinylestradiol (EE)) one non-steroidal oestrogen the diethylstilbestrol (DES) one andro-gen the testosterone (TES) and two synthetic progestogensnorgestrel (NOR) and megestrol acetate (MGA) (Table 1)based on solid phase extraction and ultrahigh performanceliquid chromatography-tandem mass spectrometry (SPE-UHPLC-MSMS) The developed method was applied tothe identification and quantification of these compoundsin wastewater samples obtained from the influents andeffluents of two wastewater treatment plants (WWTPs) ofGran Canaria (Spain) They presented different methodsof wastewater treatments WWTP 1 presented a traditionalmethod based on activated sludge while WWTP 2 used amembrane bioreactor technique

2 Materials and Methods

21 Reagents All of the hormonal compounds usedwere pur-chased from Sigma-Aldrich (Madrid Spain) Stock solutionscontaining 1000mgsdotLminus1 of each analyte were prepared by

dissolving the compound inmethanol and the solutionswerestored in glass-stoppered bottles at 4∘C prior to use Workingaqueous standard solutions were prepared daily Ultrapurewater was provided by a Milli-Q system (Millipore BedfordMA USA) HPLC-grade methanol LC-MS methanol andLC-MS water as well as the ammonia and the ammoniumacetate used to adjust the pH of the mobile phases wereobtained from Panreac Quımica (Barcelona Spain)

22 Sample Collection Water samples were collected fromthe effluents of twowastewater treatment plants located in thenorthern area of Gran Canaria in May and August of 2012WWTP 1 used a conventional activated sludge treatmentsystem while WWTP 2 employed a membrane bioreactortreatment system The samples were collected in 2 L amberglass bottles that were rinsed beforehand with methanol andultrapurewater Samples were purified through filtrationwithfibreglass filters and then with 065 120583m membrane filters(Millipore Ireland) The samples were stored in the dark at4∘C and extracted within 48 hours

23 Instrumentation For the SPE optimization the instru-ment used was an ultrahigh performance liquid chromatog-raphy with fluorescence detector (UHPLC-FD) system con-sisting of an ACQUITYQuaternary Solvent Manager (QSM)used to load samples and wash and recondition the analyticalcolumn an autosampler a column manager and a fluores-cence detector with excitation and emission wavelengths of280 and 310 nm respectively all fromWaters (Madrid Spain)

The analysis of wastewater samples was performed ina UHPLC-MSMS system from Waters (Madrid Spain)similar to the described above with a 2777 autosamplerequipped with a 25120583L syringe and a tray to hold 2mLvials and an ACQUITY tandem triple quadrupole (TQD)mass spectrometer with an electrospray ionization (ESI)interface All Waters components (Madrid Spain) werecontrolled using the MassLynx Mass Spectrometry SoftwareElectrospray ionisation parameters were fixed as followsthe capillary voltage was 3 kV in positive mode and minus2 kVin negative mode the source temperature was 150∘C thedesolvation temperature was 500∘C and the desolvation gasflow rate was 1000 Lhr Nitrogen was used as the desolvationgas and argon was employed as the collision gas

The detailed MSMS detection parameters for each hor-monal compound are presented in Table 2 and were opti-mised by the direct injection of a 1mgsdotLminus1 standard solutionof each analyte into the detector at a flow rate of 10 120583Lsdotminminus1

24 Chromatographic Conditions For the SPE optimizationthe analytical column was a 50mm times 21mm ACQUITYUHPLCBEHWaters C

18columnwith a particle size of 17120583m

(Waters Chromatography Barcelona Spain) operating at atemperature of 30∘C Analytes separation was carried outemploying the following gradient starting at 55 45 (vv)water methanol for 1 minute During 3 minutes it changedto 50 50 (vv) and stayed for 25 minutes more Finally cameback to initial conditions in 1 minute and stayed for 15

Journal of Analytical Methods in Chemistry 3

Table 1 List of hormonal compounds pKa values chemical structure and retention times

Compound pKa [21] Structure 119905119877

(min)

E3 Estriol 103

HO

OH

OH

H H

H096

E2 17120573-estradiol 103

HO

OH

H H

H218

EE 17120572-ethinylestradiol 103

HO

HO

H H

H223

E1 Estrone 103

HO

O

H

H H220

DES Diethylstilbestrol 102

HO

OH

235

TES Testosterone 151

OH

OH H

H240

MGA Megestrol acetate

O

O

O

OH

H

H306

NOR Levonorgestrel 131

OH

O

H

H

H

H263

minutes Therefore the analysis took 9 minutes at a flow of05mLsdotminminus1

For the analysis of real samples aUHPLC-MSMS systemwas used The analytical column was the same and themobile phase was water and methanol adjusted with a bufferconsisting in 01 vv ammonia and 15mM of ammoniumacetate The analysis was performed in gradient mode at aflow rate of 03mLsdotminminus1The gradient started at 50 50 (vv)mixture of water methanol which changed to 25 75 (vv) in3 minutes and returned to 50 50 in 1 minute more Finallythe gradient stayed calibrating for another 15 minutes moreThe sample volume injected was 5120583L

3 Results and Discussion

31 Optimization of Solid-Phase Extraction (SPE) There area number of parameters that affect SPE procedure such as

type of sorbent pH ionic strength sample and desorptionvolumes and wash step To optimize these parameters itused Milli-Q water spiked with a solution of fluorescenceoestrogens (estriol 17120573-estradiol and 17120572-ethinylestradiol)to obtain a final concentration of 250120583gsdotLminus1

The first parameter to optimize is the choice of sorbentsince it controls the selectivity affinity and capacity overanalytes In this study the SPE cartridges used were OASISHLB SepPak C

18(both from Waters Madrid Spain) and

BondElut ENV (fromAgilent Madrid Spain) Keeping otherparameters fixed (ionic strength of 0 sample volume of100mL) the cartridges were studied at three different pHs(5 8 and 11) From the results obtained it can be observedthat the better signals are found for SepPak C

18cartridge

(Figure 1)After choosing the optimum cartridge we used an initial

experimental design of 23 to study the influence of pH ionic

4 Journal of Analytical Methods in Chemistry

Table 2 Mass spectrometer parameters for the determination of target analytes

Compound Precursor ion(mz)

Capillary voltage(Ion mode)

Quantification ionmz(collision potential V)

Quantification ionmz(collision potential V)

E3 2872 minus65V (ESI minus) 1710 (37) 1452 (39)E2 2712 minus65V (ESI minus) 1451 (40) 1831 (31)EE 2952 minus60V (ESI minus) 1450 (37) 1589 (33)E1 2692 minus65V (ESI minus) 1450 (36) 1430 (48)DES 2671 minus50V (ESI minus) 2371 (29) 2511 (25)TES 2892 38V (ESI +) 1870 (18) 1040 (21)MGA 3855 30V (ESI +) 2673 (15) 2242 (30)NOR 3132 38V (ESI +) 1090 (26) 2451 (18)

0

500

1000

1500

2000

2500

E3 E2 EE

Peak

area

Cartridge optimizationOASIS HLB pH = 5

OASIS HLB pH = 8

OASIS HLB pH = 11SepPak C18 pH = 5

SepPak C18 pH = 8

SepPak C18 pH = 11BondElut ENV pH = 5

BondElut ENV pH = 8

BondElut ENV pH =11

Figure 1 Optimization of SPE cartridges

strength and sample volume over extraction process Theexperimental design was obtained using Statgraphics Plussoftware 51 and the statistics study was done with IBM SPSSStatistics 19 We assessed two levels and three parameters pH(3 and 8) ionic strength (0 and 30 of NaCl) and samplevolume (50 and 250mL) to obtain the influence of eachparameter and the variable correlation to each other In thisstudy it is observed that the ionic strength and sample volumehad the major influence on the recoveries of the analytesFor that a 32 factorial design to optimize these two variablesat three levels per parameter (0 15 and 30 of NaCl forionic strength and 50 100 y 250mL for sample volume) wasused Figure 2 shows the response surface obtained for theestriol and 17120572-ethinylestradiol The results obtained showedthat an increment of the ionic strength did not producean increase in the response area of the compound and theoptimum volume was 250mL Because of that a solutionwithout salt addition and 250mL of sample volume waschosen Finally the desorption volume (1mLofmethanol and2mL of methanol in one and two steps) and wash-step (5mL

ofMilli-Q water and 5mL ofMilli-Q water with 5 and 10 ofmethanol vv) were assayed to complete the optimization ofthe SPE process The optimum values were 2mL of methanolin one step and 5mL of Milli-Q water without methanolrespectively

In accordance with the obtained results the optimumconditions for SPE procedure were SepPak C

18cartridge

250mL of sample at pH = 8 and 0 of NaCl desorptionwith 2mL of methanol in one step and wash step with5mL of Milli-Q water In these conditions we achieved apreconcentration factor of 125 In Figure 3 a chromatogramwith the optimum conditions is shown where the peaksof all compounds in their corresponding transitions can beobserved

32 Analytical Parameters Because of the SPE optimizationthat was done only with fluorescent compounds (estriol 17120573-estradiol and 17120572-ethinylestradiol) it was necessary to studythe recoveries of all the hormonal compounds using theoptimized SPE-UHPLC-MSMSmethod All the compoundsunder study showed good recoveries over 73 except thediethylstilbestrol with a recovery of 507

A calibration curve was used for the quantification ofthe analytes by diluting the stock solution of each analyteinto the samples to concentrations ranging between 1 and100 120583gsdotLminus1 Analysis was conducted by UHPLC-MSMS andlinear calibration plots for each analyte (1199032 gt 099) wereobtained based on their chromatographic peak areas

The limit of detection (LOD) and the limit of quantifi-cation (LOQ) for each compound were calculated from thesignal-to-noise ratio of each individual peak The LOD wasdefined as the lowest concentration that gave a signal-to-noiseratio that was greater than 3 The LOQ was defined as thelowest concentration that gave a signal to noise ratio that wasgreater than 10The LODs ranged from015 to 935 ngsdotLminus1 andthe LOQs ranged from 049 to 3118 ngsdotLminus1

The performance and reliability of the process werestudied by determining the repeatability of the quantificationresults for all target analytes under the described conditionsusing six samples (119899 = 6) The relative standard deviations(RSDs) were lower than 84 in all cases indicating a

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 5: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Editorial Board

M Abdel-Rehim SwedenH Y Aboul Enein EgyptSilvana Andreescu USAA N Anthemidis GreeceA N Araujo PortugalR W Arndt SwitzerlandAna Cristi B Dias BrazilPierangelo Bonini ItalyArthur C Brown USAAntony C Calokerinos GreeceRicardo J Cassella BrazilXin-Sheng Chai ChinaO Chailapakul ThailandXingguo Chen ChinaC Collombel FranceW T Corns UKMiguel de la Guardia SpainIvonne Delgadillo PortugalE Dellacassa UruguayCevdet Demir TurkeyM Bonner Denton USAGregory W Diachenko USAM E Diaz-Garcia SpainDieter M Drexler USAJianxiu Du ChinaJenny Emneus DenmarkG Eppe BelgiumJosep Esteve-Romero SpainO Fatibello-Filho BrazilPaul S Francis AustraliaJuan F Garcia-Reyes SpainC Georgiou GreeceKate Grudpan ThailandR Haeckel Germany

Arafa I Hamed EgyptKaroly Heberger HungaryBernd Hitzmann GermanyChih-Ching Huang TaiwanI Isildak TurkeyJaroon Jakmunee ThailandXiue Jiang ChinaSelhan Karagoz TurkeyHiroyuki Kataoka JapanSkip Kingston USAChristos Kontoyannis GreeceR Kowalski PolandAnnamalai S Kumar IndiaIlkeun Lee USAJoe Liscouski USAEulogio J Llorent-Martinez SpainMercedes G Lopez MexicoMiren Lopez de Alda SpainLarisa Lvova ItalyJos Carlos Marques PortugalChristophe A Marquette FranceJean Louis Marty FranceSomenath Mitra USASerban C Moldoveanu USAMaria B Montenegro PortugalG A Nagana Gowda USAMilka Neshkova BulgariaB Nikolova-Damyanova BulgariaSune Nygaard DenmarkC K OrdquoSullivan SpainGangfeng Ouyang ChinaSibel A Ozkan TurkeyVeronica Pino SpainKrystyna Pyrzynska Poland

Jose B Quintana SpainMohammad A Rashid BangladeshD P S Rathore IndiaPablo Richter ChileFabio R P Rocha BrazilErwin Rosenberg AustriaGiuseppe Ruberto ItalyAntonio R Medina SpainBradley B Schneider CanadaGuoyue Shi ChinaJesus S Gandara SpainHana Sklenarova Czech RepublicN H Snow USAP B Stockwell UKF O Suliman OmanIt-Koon Tan SingaporeD G Themelis GreeceNilgun Tokman TurkeyNelson Torto South AfricaMarek Trojanowicz PolandParis Tzanavaras GreeceBengi Uslu TurkeyKrishna K Verma IndiaAdam Voelkel PolandFang Wang USAHai-Long Wu ChinaHui-Fen Wu TaiwanQingli Wu USAMengxia Xie ChinaRongda Xu USAXiu-Ping Yan ChinaLu Yang CanadaC Yin China

Contents

Analysis and Fate of Emerging Pollutants during Water Treatment Fei Qi Guang-Guo Ying Kaimin ShihJolanta Kumirska Elif Pehlivanoglu-Mantas and Xiaojun LuoVolume 2013 Article ID 256956 1 page

Occurrence and Removal Characteristics of Phthalate Esters from Typical Water Sources in NortheastChina Yu Liu Zhonglin Chen and Jimin ShenVolume 2013 Article ID 419349 8 pages

Simultaneous Determination of Hormonal Residues in Treated Waters Using Ultrahigh PerformanceLiquid Chromatography-Tandem Mass Spectrometry Rayco Guedes-Alonso Zoraida Sosa-Ferreraand Jose Juan Santana-RodrıguezVolume 2013 Article ID 210653 8 pages

Removal Efficiency and Mechanism of Sulfamethoxazole in Aqueous Solution by Bioflocculant MFXJie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei WeiVolume 2013 Article ID 568614 8 pages

Pyrite Passivation by Triethylenetetramine An Electrochemical Study Yun Liu Zhi Dang Yin Xuand Tianyuan XuVolume 2013 Article ID 387124 8 pages

A Green Preconcentration Method for Determination of Cobalt and Lead in Fresh Surface and WasteWater Samples Prior to Flame Atomic Absorption Spectrometry Naeemullah Tasneem Gul KaziFaheem Shah Hassan Imran Afridi Sumaira Khan Sadaf Sadia Arian and Kapil Dev BrahmanVolume 2012 Article ID 713862 8 pages

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 256956 1 pagehttpdxdoiorg1011552013256956

EditorialAnalysis and Fate of Emerging Pollutants duringWater Treatment

Fei Qi1 Guang-Guo Ying2 Kaimin Shih3 Jolanta Kumirska4

Elif Pehlivanoglu-Mantas5 and Xiaojun Luo2

1 Beijing Key Lab for Source Control Technology of Water Pollution College of Environmental Science and EngineeringBeijing Forestry University No 35 Qinghua East Road Beijing 100083 China

2 State Key Laboratory of Organic Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of SciencesGuangzhou 510640 China

3Department of Civil Engineering The University of Hong Kong Pokfulam Road Hong Kong4Department of Environmental Analysis Faculty of Chemistry University of Gdansk Sobieskiego 1819 80-952 Gdansk Poland5 Environmental Engineering Department Istanbul Technical University Ayazaga Campus Maslak 34469 Istanbul Turkey

Correspondence should be addressed to Fei Qi qifeibjfueducn

Received 23 April 2013 Accepted 23 April 2013

Copyright copy 2013 Fei Qi et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Emerging pollutants defined as compounds that are notcurrently covered by existing water-quality regulations allover the world have not been studied widely before and arethought to be potential threats to environmental ecosystemsand human health This special issue compiles 5 excitingpapers which are very meticulously performed researches

Generally emerging pollutants encompass a diversegroup of compounds including pharmaceuticals drugs ofabuse personal-care products (PCPs) steroids and hor-mones surfactants perfluorinated compounds (PFCs) flameretardants industrial additives and agents gasoline additivesnew disinfection byproducts (DBPs) nanomaterials and thetoxic minerals

The analysis methods occurrence and fate of hormonaland endocrine disruptors compounds (EDCs) were dis-cussed in two papers of this special issue R Guedes-Alonsoet al determine the hormonal residues in treated water byultrahigh performance liquid chromatography-tandem massspectrometry (UPLC-MS) and evaluate the efficiency ofthe conventional wastewater treatment for the removal ofhormonal compounds Moreover Y Liu et al study anotherkinds of PPCPs named as phthalate esters that is typicalkind of EDCs The occurrence in a surface water and theremoval efficiency in a traditional drinking water treatmentpalnt are studied According to results of the two papers

the occurrence and fate of hormonal and EDCs in water orwastewater treatment are very clear

J Xing et al report a new wastewater treatment technol-ogy bioflocculation for the removal of sulfamethoxazole thatis a typical pharmaceutical in wastewater The performanceand the reaction mechanism of the biodegradation of sul-famethoxazole by the bioflocculation are discussed in depthMoreover the optimum reaction condition is obtained

The heavy metal and toxic mineral are also importantpollutants in the environment especially in the mining areaTwo papers of this issue are focused on this K Naeemul-lah et al report a green preconcentration method for thedetermination of cobalt and lead in water Y Liu et al do anovel research on the electrochemical reaction of pyrite as asimulation of the natural environmental

By compiling this special issue we hope to enrich ourreaders and researchers on the analysis and fate of emergingpollutants during water treatment

Fei QiGuang-Guo Ying

Kaimin ShihJolanta Kumirska

Elif Pehlivanoglu-MantasXiaojun Luo

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 419349 8 pageshttpdxdoiorg1011552013419349

Research ArticleOccurrence and Removal Characteristics of Phthalate Estersfrom Typical Water Sources in Northeast China

Yu Liu Zhonglin Chen and Jimin Shen

State Key Laboratory of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Jimin Shen shenjiminhiteducn

Received 21 December 2012 Accepted 3 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Yu Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The presence of phthalate esters (PAEs) in the environment has gained a considerable attention due to their potential impactson public health This study reports the first data on the occurrence of 15 PAEs in the water near the Mopanshan Reservoirmdashthenew and important water source of Harbin city in Northeast China As drinking water is a major source for human exposureto PAEs the fate of target PAEs in the two waterworks (Mopanshan Waterworks and Seven Waterworks) was also analyzed Theresults demonstrated that the total concentrations of 15 PAEs in the water near the Mopanshan Reservoir were relatively moderateranging from 3558 to 92265 ngL with the mean value of 29431 ngL DBP and DEHP dominated the PAE concentrations whichranged from 525 to 44982 ngL and 1289 to 65709 ngL respectivelyThe occurrence and concentrations of these compoundswereheavily spatially dependent Meanwhile the results on the waterworks samples suggested no significant differences in PAE levelswith the input of the raw waters Without effective and stable removal of PAEs after the conventional drinking water treatment inthe waterworks (258 to 765) the risks posed by PAEs through drinking water ingestion were still existing which should bepaid special attention to the source control in theMopanshan Reservoir and some advanced treatment processes for drinking watersupplies

1 Introduction

Phthalate acid esters a class of chemical compounds mainlyused as plasticizers for polyvinyl chloride (PVC) or to alesser extent other resins in different industrial activities areubiquitous in the environment and have evoked interest inthe past decade due to endocrine disrupting effects and theirpotential impacts on public health [1ndash3]

Worldwide production of PAEs is approximately 6 mil-lion tons per year [4] As PAEs are not chemically boundto the polymeric matrix in soft plastics they can enter theenvironment by losses during manufacturing processes andby leaching or evaporating from final products [5]Thereforethe occurrence and fate of specific PAEs in natural waterenvironments have been observed and also there are a lot ofconsiderable controversies with respect to the safety of PAEsin water [5ndash10]

Six PAE compounds including dimethyl (DMP) diethyl(DEP) dibutyl (DBP) butylbenzyl (BBP) di(2-ethylhexyl)

(DEHP) and di-n-octyl phthalate (DNOP) are classifiedas priority pollutants by the US Environmental ProtectionAgency (EPA) Though the toxicity of PAEs to humans hasnot been well documented for some years the Ministry ofEnvironmental Protection in China has regulated phthalatesas environmental pollutants In addition the standard inChina concerning analytical controls on drinkingwaters doesnot specifically identify any PAEs as organic pollutant indexesto be determined by the new drinking water standard in 2007(Standard for drinking water quality GB5749-2006) whichwas forced to be monitored for the drinking water supplies in2012 Consequently official data about the presence of thesepollutants in the aquatic environment of some cities are notavailable

Harbin the capital of Heilongjiang Province is a typicallyold industrial base and economically developed city with apopulation of over 3million inNortheast China As the newlyenabledwater source forHarbin cityMopanshanwaterworkssupply the whole city with drinking water through long

2 Journal of Analytical Methods in Chemistry

China

HarbinMopanshan

Reservoir

LongfengshanReservoir

Figure 1 Spatial distribution of the 16 sampling sites near the Mopanshan Reservoir in Northeast China

distance transfer from the Mopanshan Reservoir To theauthorsrsquo knowledge the occurrence and fate of PAEs in thewater near this area and its relative waterworks have notpreviously been examined

The objectives of this study were (i) to determine theoccurrence of PAEs and clarify the fate and distribution ofthe pollutants in the water source (ii) to examine the twowaterworks where traditional drinking water treatment stepwas evaluated on the PAEs removal efficiencies and (iii) toevaluate the potential for adverse effects of PAEs on humanhealth Therefore the investigation of PAEs in the water canprovide a valuable record of contamination in Harbin city

2 Materials and Methods

21 Chemical Fifteen PAEs standard mixture includingdimethyl phthalate diethyl phthalate diisobutyl phthalatedi-n-butyl phthalate di(4-methyl-2-pentyl) phthalate di(2-ethoxyethyl) phthalate di-n-amyl phthalate di-n-hexylphthalate butyl benzyl phthalate di(hexyl-2-ethylhexyl)phthalate di(2-n-butoxyethyl) phthalate dicyclohexyl phthal-ate di(2-ethylhexyl) phthalate di-n-nonyl phthalate di-n-octylphthalate at 1000 120583gmL each and surrogate standardsconsisting of diisophenyl phthalate di-n-phenyl phthal-ate and di-n-benzyl phthalate in a mixture solution of500120583gmL each were supplied by AccuStandard Inc Asthe internal standard benzyl benzoate was also purchasedfrom AccuStandard Inc All solvents (acetone hexane anddichloromethane) used were HPLC-grade and were pur-chased from J T Baker Co (USA) Anhydrous sodiumsulfate (Tianjin Chengguang Chemical Reagent Co China)was cleaned at 600∘C for 6 h and then kept in a desiccatorbefore use

22 Sample Collection and Preparation Harbin the capitalof Heilongjiang province in China imports nearly all of itsdrinking water from two sources the Mopanshan Reservoir

Raw water Coagulation sedimentation Filtration Tank

Sampling site Sampling site

Figure 2 Schematic diagram of the waterworks

(long-distance transport project) and the Songhua River (oldwater source)

Water samples from the Mopanshan Reservoir andMopanshan waterwork were collected in 2008 The locationsof the sampling sites near the Mopanshan Reservoir are pre-sented in Figure 1 as a comparison sampling from anotherHarbin water supplymdashSeven waterworks with water sourcefrom the SonghuaRiverwas performed in 2011 In eachwater-works with considering the hydraulic retention time threesets of raw water samples (influent) were taken and thenthe final finished waters (effluent) after the whole treatmentprocess were carried out for the collectionsThe flow diagramof the waterworks is shown in Figure 2

Samples were collected using 20 L glass jars from 05mbelow the water surface During the whole sampling processthe global position system was used to locate the samplingstations (details in Table 1) All samples were transferred tothe laboratory directly after sampling and stored at 4∘C priorto extraction within 2 d

Water samples were filtered under vacuum through glassfiber filters (07 120583mpore sizes) Prior to extraction each sam-ple was spiked with surrogate standards The water sampleswere extracted based on a classical liquid phase extractionmethod (USEPA method 8061) with slight modificationsBriefly 1 L of water samples was placed in a separating funneland extracted by means of mechanical shaking with 150mLdichloromethane and then with filtration on sodium sulfate(about 20 g) the organic extracts were concentrated usinga rotary evaporator The exchange of solvent was done byreplacing dichloromethane with hexane Finally they were

Journal of Analytical Methods in Chemistry 3

Table 1 Detailed descriptions of the sampling locations

Number Sampling site Name Latitude Longitude1 Lalin Jinsan Bridge Mangniu River E127∘0210158405310158401015840 N45∘510158404510158401015840

2 Xingsheng Town Gaojiatun Lalin River E127∘0610158401110158401015840 N44∘5110158405710158401015840

3 Dujia Town Shuguang Lalin River E127∘1010158404410158401015840 N44∘4810158404110158401015840

4 Shanhe Town Taipingchuan Lalin River E127∘1810158403610158401015840 N44∘4310158405010158401015840

5 Xiaoyang Town Qichuankou Lalin River E127∘2310158405410158401015840 N44∘3910158404610158401015840

6 Shahezi Town Mopanshan Reservoir E127∘3810158405910158401015840 N44∘2410158401710158401015840

7 Shahezi Town Gali Lalin River E127∘3510158401710158401015840 N44∘3110158405610158401015840

8 Chonghe Town Changcuizi Mangniu River E127∘4610158403610158401015840 N44∘3510158404610158401015840

9 Chonghe Town Xingguo Mangniu River E127∘3510158401710158401015840 N44∘3110158405710158401015840

10 Longfeng Town Mangniu River E127∘3510158401910158401015840 N44∘4310158404810158401015840

11 Changpu Town Zhonghua Mangniu River E127∘1610158403010158401015840 N45∘110158404210158401015840

12 Erhe Town Shuanghe Mangniu River E127∘1810158403210158401015840 N45∘410158402810158401015840

13 Zhiguang Town Songjiajie Mangniu River E127∘341015840310158401015840 N45∘110158402010158401015840

14 Zhiguang Town Wuxing Mangniu River E127∘2910158402010158401015840 N45∘010158404310158401015840

15 Changpu Town Xingzhuang Mangniu River E127∘1010158404210158401015840 N45∘410158403610158401015840

16 Yingchang Town Xingguang Lalin River E126∘551015840810158401015840 N45∘91015840010158401015840

reduced to 05mL under gentle nitrogen flow The internalstandard was added to the sample prior to instrumentalanalysis

23 Chemical Analysis The extracted compounds weredetermined by gas chromatography coupled to mass spec-trometer analysis as described in other publications [1112] Briefly extracted samples were injected into an Agilent6890 Series GC equipped with a DB-35MS capillary column(Agilent 30m times 025mm id 025120583m film thickness) andan Agilent 5973 MS detector operating in the selective ionmonitoring mode The column temperature was initially setat 70∘C for 1min then ramped at 10∘Cmin to 300∘C andheld constant for 10min The transfer line and the ion sourcetemperature were maintained at 280 and 250∘C respectivelyHelium was used as the carrier gas at a flow rate of 1mLminThe extracts (20 120583L) were injected in splitless mode with aninlet temperature of 300∘C

24 Quality Assurance and Quality Control All glasswarewas properly cleaned with acetone and dichloromethanebefore use Laboratory reagent and instrumental blanks wereanalyzed with each batch of samples to check for possiblecontamination and interferences Only small levels of PAEswere found in procedural blanks in some batches andthe background subtraction was appropriately performed inthe quantification of concentration in the water samplesCalibration curves were obtained from at least 3 replicateanalyses of each standard solution The surrogate standardswere added to all the samples to monitor matrix effectsRecoveries of PAEs ranged from 62 to 112 in the spikedwater and the surrogate recoveries were 751 plusmn 127 fordiisophenyl phthalate 723 plusmn 143 for di-n-phenyl phtha-late and 1026 plusmn 104 for di-n-benzyl phthalate in thewater samples The determination limits ranged from 6 to30 ngL A midpoint calibration check standard was injected

as a check for instrumental drift in sensitivity after every10 samples and a pure solvent (methanol) was injected as acheck for carryover of PAEs from sample to sample All theconcentrations were not corrected for the recoveries of thesurrogate standards

3 Results and Discussion

31 PAEs in Water Source The PAEs in the waters fromthe sampling sites near the Mopanshan Reservoir wereinvestigated and the results are presented in Table 2 Thesum15

PAEs concentrations ranged from 3558 to 92265 ngLwith the geometric mean value of 29431 ngL Among the15 PAEs detected in the waters DIBP DBP and DEHP weremeasured in all the samples with the average concentrationsbeing 1966 8014 and 17741 ngL respectively The threePAE congeners are important and popular addictives inmany industrial products including flexible PVC materialsand household products suggesting the main source of PAEcontaminants in the water [13] The correlations of the con-centration of DEHP DBP and DIBP with the concentrationsof total PAEs in the water samples are shown in Figure 3and a relatively significant correlation between sum

15

PAEs andDEHP concentration was found suggesting the importantpart played by DEHP in total concentrations of PAEs inthe water bodies near the Mopanshan Reservoir In otherwords the contribution of DEHP to total PAEs was higherthan that of other PAE congeners in the water samples Inaddition DMP DEP and DNOP with the mean value of140 284 and 541 ngL respectively only detected at somesampling sites and have also attracted much attention asthe priority pollutants by the China National EnvironmentalMonitoring Center On the contrary the concentrations of6 PAEs (DMEP BMPP BBP DBEP DCHP and DNP) werebelow detection limits in all the water samples near theMopanshan Reservoir which is easily explained in terms ofmuch lower quantities of present use in China

4 Journal of Analytical Methods in Chemistry

0 2000 4000 6000 80000

2000

4000

6000

Con

cent

ratio

ns (n

gL)

DEHP

119903 = 0885 119875 lt 001

sum15PAEs (ngL)

(a)

0 2000 4000 6000 80000

2000

4000

Con

cent

ratio

ns (n

gL)

sum15PAEs (ngL)

DBP

119903 = 0812 119875 lt 001

(b)

1000

500

0

0 2000 4000 6000 8000sum15PAEs (ngL)

DIBP

Con

cent

ratio

ns (n

gL)

119903 = 0724 119875 lt 001

(c)

Figure 3 Correlations of the concentration of the major PAEs (DEHP DBP and DIBP) with the concentrations of total PAEs in the watersamples

Table 2 Concentrations of 15 PAEs in water samples near the Mopanshan Reservoir

PAEs Abbreviation Water (ngL)Range Mean Frequency

Dimethyl phthalate DMP ndndash424 140 816Diethyl phthalate DEP ndndash550 284 1516Diisobutyl phthalate DIBP 400ndash6588 1966 1616Dibutyl phthalate DBP 525ndash44982 8014 1616bis(2-methoxyethyl)phthalate DMEP nd nd 016bis(4-methyl-2-pentyl)phthalate BMPP nd nd 016bis(2-ethoxyethyl)phthalate DEEP ndndash546 128 516Dipentyl phthalate DPP ndndash925 455 1016Dihexyl phthalate DHXP ndndash651 162 516Benzyl butyl phthalate BBP nd nd 016bis(2-n-butoxyethyl)phthalate DBEP nd nd 016Dicyclohexyl phthalate DCHP nd nd 016bis(2-ethylhexyl)phthalate DEHP 1289ndash65709 17741 1616Di-n-octyl phthalate DNOP ndndash4482 541 516Dinonyl phthalate DNP nd nd 016sum15

PAEs 3558ndash92265 29431 mdash

The distribution of 15 PAEs (sum15

PAEs) studied and6 US EPA priority PAEs (sum

6

PAEs including DMP DEPDIBP DBP DEHP and DNOP) in the waters from differentsampling sites are shown in Figure 4 There was an obviousvariation in the total sum

15

PAEs concentrations in water sam-ples near the Mopanshan Reservoir the concentrations ofsum6

PAEs from the same sampling sites varied from 2690 to90860 ngL with an average of 28686 ngL the distributionspectra of which observed for all the sampling sites weresimilar tosum

15

PAEsThe highest levels of PAEs contaminationwere seen on the sampling site 3 followed by some relativelyheavily polluted sites (site 16 13 9 10 and 11) indicating thatthese sites served as important PAE sources and the spatialdistribution of PAEs was site specific The levels in the watersexamined varied over a wide range especially in theMangniu

River near theMopanshan Reservoir (in some case overmorethan one order of magnitude) In general it should be notedthat there might be a relation of PAEs levels with the input oflocal waste such as sewage water food packaging and scrapmaterial near the sampling point which were found duringthe sampling period

32 PAE Congener Profiles in the Water Different PAE pat-terns may indicate different sources of PAEs Measurementof the individual PAE composition is helpful to track thecontaminant source and demonstrate the transport and fateof these compounds in water [11] The relative contributionsof the 9 detectable PAE congeners to thesum

15

PAEs concentra-tions in the water are presented in Figure 5 It is clear thatDEHP was the most abundant in the water samples with

Journal of Analytical Methods in Chemistry 5

0

500

1000

1500

4000

6000

8000

10000

Con

cent

ratio

ns (n

gL)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

sum15PAEssum6PAEs

Figure 4 Spatial distributions of the 16 sampling sites near theMopanshan Reservoir

the exception of site 2 3 and 11 contributions ranging from331 to 963 followed byDBP ranging from 21 to 363The results are consistent with the above data for overallanalysis that DBP and DEHP are the dominant componentsof the PAEs distribution pattern in each sampling site whichreflected the different pattern of plastic contaminant inputduring the sampling period Similarly DIBP and DBP areused in epoxy resins or special adhesive formulations withthe different proportions of these two PAE congeners whichwere also the important indicator of the information pollutedby PAEs for the sampling locations Although the limitedsample number draws only limited conclusions there is stillreason to note that a leaching from the plastic materials intothe runoff water is possible and that water runoff from thecontaminated water is a burden pathway from differentsources of PAEs [14]

33 Comparison with Other Water Bodies Comparison withthe total PAEs concentrations is nevertheless very limited dueto the different analysis compounds However the individualPAE namely DBP and DEHP is by far the most abundantin other researches and it is possible to make a camparisonwith our findings In this case the results of DBP and DEHPconcentrations published in literatures for kinds of waterbodies are presented together in Table 3

The DEHP and DBP concentrations of the present studyshowed to some extent lower concentration levels than thosereported in the other water bodies in China In comparisonthe results were comparable or similar to those from theexaminations described in other foreign countries For exam-ple as shown in Table 3 the DEHP concentrations were sim-ilar to the surface waters from the Netherlands and Italydescribed in the literature Meanwhile these concentrationsin this study were quite lower than the Yangtze River andSecond Songhua River in China

0

20

40

60

80

100

DEEP DPP DHXP DEHP DNOP DBP

DIBP DEP DMP

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

Com

posit

ion

()

Figure 5 PAE composition of thewater samples in 16 sampling sites

In conclusion as compared to the results of other studiesthe waters near the Mopanshan Reservoir were moderatelypolluted by PAEs Therefore there is a definite need to set upa properly planned and systematic approach to water controlnear the Mopanshan Reservoir

34 PAE Levels in the Waterworks The Mopanshan Water-works (MPSW) equipped essentially with the water sourceof the Mopanshan Reservoir has been investigated in orderto assess the fate of the PAEs during the drinking watertreatment process For comparison a sampling campaign forthe determination of PAEs levels in the Seven Waterworks(SW waterworks with the old water source of the SonghuaRiver) was carried out Both waterworks operate coagulationsedimentation and followed by filtration treatment processwhich are typical traditional drinking water treatment

The measured concentrations in the raw and finishedwater of the two investigated waterworks are shown inFigure 6 Six out of fifteen PAEs were detected in the fin-ished water from the two waterworks The detected PAEswere DMP DEP DIBP DBP DEHP and DNOP and theother investigated phthalates are of minor importance withconcentrations all below the limit of detection As showin Figure 6 the measured concentrations of the analyzedPAEs in the finished water of the two waterworks variedstronglyThemost important compound in the finishedwaterwas DEHP with the mean concentration of 34737 and40592 ngL for the MPSW and SW respectively suggestingthe highest relative composition of total PAE concentrationsin the drinking water

For the raw water from the different water sources DMPand DIBP concentrations in the MPSW were much lowerthan the ones in the SW and the concentrations of DEPDBP DEHP andDEHPwere relatively comparable in the two

6 Journal of Analytical Methods in Chemistry

Table 3 Comparison of the concentrations of DEHP and DBP in the water bodies (ngL)

Location DEHP DBP ReferenceRange Median Mean Range Median Mean

Surface water Germany 330ndash97800 2270 mdash 120ndash8800 500 mdash [14]Surface water the Netherlands ndndash5000 320 mdash 66ndash3100 250 mdash [15]Seine River estuary France 160ndash314 mdash mdash 67ndash319 mdash mdash [16]Tama River Japan 13ndash3600 mdash mdash 8ndash540 mdash mdash [17]Velino River Italy ndndash6400 mdash mdash ndndash44300 mdash mdash [2]Surface water Taiwan ndndash18500 mdash 9300 1000ndash13500 mdash 4900 [18]Surface water Jiangsu China 556ndash156707 mdash mdash 16ndash58575 mdash mdash [19]Yangtze River mainstream China 3900ndash54730 mdash mdash ndndash35650 mdash mdash [20]Middle and lower Yellow River China 347ndash31800 mdash mdash ndndash26000 mdash mdash [21]Second Songhua River China ndndash1752650 370020 mdash ndndash5616800 mdash 717240 [22]Urban lakes Guangzhou China 87ndash630 170 240 940ndash3600 1990 2030 [11]Xiangjiang River China 620ndash15230 mdash mdash mdash mdash mdash [23]This study 1289ndash65709 6710 17741 525ndash44982 1103 8014

0

500

1000

100001200014000

0

20

40

60

80

100

Raw waterFinished waterRemoval

Rem

oval

()

Con

cent

ratio

ns (n

gL)

DMP DEP DIBP DBP DEHP DNOP

(a)

Raw waterFinished waterRemoval

0

500

1000

1500

2000

100001200014000

0

20

40

60

80

100C

once

ntra

tions

(ng

L)

Rem

oval

()

DMP DEP DIBP DBP DEHP DNOP

(b)

Figure 6 PAEs detected in the water samples from the MPSW (a) and SW (b)

waterworks The removal of PAEs by these two waterworksranged from 258 to 765 which varied significantly with-out stable removal efficienciesThe lower removal efficienciesfor DMP and DNOP were observed in the SW with theremoval less than 30 For both the waterworks no soundremoval efficiencies were obtained for the PAEs indicatingthat the traditional drinking water treatment cannot showgood performance to eliminate these micro pollutants whichhas nothing to do with the type of the water source

Traditional drinking water treatment focuses on dealingwith the particles and colloids in terms of physical processesMany studies of the environmental fates of PAEs have demon-strated that oxidation or microbial action is the principalmechanism for their removal in the aquatic systems [24ndash26]Therefore the treatment process should be the combinationswith the key techniques for removing PAEs from the waterOn the other hand since the removal efficiencies of PAEs by

these advance drinking water treatments in waterworks hasnot been systematically studied to date further research inthis direction would seem to be required

35 Exposure Assessment of PAEs in Water To evaluate thepotential and adverse effects of PAEs quality guidelines forsurface water and drinking water standard were used Theresults indicated that the mean concentrations of DBP andDEHP at levels were well below the reference doses (RfD)regarded as unsafe by the EPA for the surface water Thelevels were not also above the RfD recommended by China(Environmental Quality Standard for SurfaceWater of ChinaGB3838-2002) On the other hand the amounts of DEHPpresent in public water supplies should be lower than thedrinkingwater standard (0006mgL for EPA and 0008mgLfor China) According to the results the concentrations of

Journal of Analytical Methods in Chemistry 7

DEHP in drinkingwater samples from theMPSWwere lowerthan the limited value

PAEs are also considered to be endocrine disruptingchemicals (EDCs) whose effects may not appear until long-term exposure According to the results PAEs were detectedin the drinking water constantly ingested in daily life indi-cating that drinking water is an important source of humanexposure to PAEs contaminants Assuming a daily waterconsumption rate of 2 L and an average body weight of 60 kgfor adults the average daily intake of DEHP DBP and DIBPby way of drinking water from MPSW was calculated to be1158 1352 and 81 ngkgd respectively In comparison thevalues of SW with the water source of the Songhua Riverwere relatively higher with the calculated results of 1353140 and 155 ngkgd for DEHP DBP and DIBP respectivelyIn this study the estimated daily intake levels of DEHPfrom the drinking water were quite lower than the RfDof 20000 ngkgd released by the EPA However some ofPAEs are partly metabolised in the organism and futureexperiments should be focused on determining the potentialeffects of the metabolites [27]

Currently treated water from the Songhua River is fornonpotable uses and MPSW is the exclusive waterworks runfor the water supply of Harbin city However populationgrowth and drought cycle are limited by the availability of rawwater from theMopanshan Reservoir Tomeet the increasingdemand local and regional water authorities have begun acampaign of second water supply project from the SonghuaRiver again which needs the protection of the Songhua Riverand advanced water treatment for the source

4 Conclusions

This study provided the first detailed data on the contami-nation status of 15 PAEs in the water near the MopanshanReservoir The concentration range of 15 PAEs in the sampleswas from 3558 to 92265 ngL with the mean value of29431 ngL DEHP andDBPwere themain pollutants among15 PAEs accounting for the main watershed pollution Theoccurrence and distribution of PAEs from different samplingsites in the water source varied largely suggesting that thespatial distribution of PAEs was site specific In additionthe monitoring of PAEs in the waterworks also showed thatPAEs can be detected in the drinking water and certaintoxicological risks to drinking water consumers were foundThese results reported here contribute to an understandingof how PAE contaminants are distributed in the new watersource and the waterworks in Harbin city as well as forminga basis for further modeling risk assessment and selection ofdrinking water treatment technology

In conclusion the results implied that no urgent reme-diation measures were required with respect to PAEs in thewaters However the ecological and health effects of thesesubstances through drinkingwater at the relatively lower con-centrations still need further notice in light of their possiblebiological magnifications Therefore the long-term sourcecontrol in the water and adding advanced treatment processfor drinking water supplies should be given special attentionin this area

Acknowledgments

This work was supported by the National Natural ScienceFoundation of China (1077029) the Funds for CreativeResearch Groups of China (Grant no 51121062) the NationalNatural Science Foundation of China (51078105) and theOpen Project of the State Key Laboratory of Urban WaterResource and Environment Harbin Institute of Technology(no QA201019)

References

[1] M Nikonorow H Mazur and H Piekacz ldquoEffect of orallyadministered plasticizers and polyvinyl chloride stabilizers inthe ratrdquo Toxicology and Applied Pharmacology vol 26 no 2 pp253ndash259 1973

[2] M Vitali M Guidotti G Macilenti and C Cremisini ldquoPhtha-late esters in freshwaters asmarkers of contamination sourcesmdasha site study in ItalyrdquoEnvironment International vol 23 no 3 pp337ndash347 1997

[3] G Latini C de Felice G Presta et al ldquoIn utero exposure todi-(2-ethylhexyl)phthalate and duration of human pregnancyrdquoEnvironmental Health Perspectives vol 111 no 14 pp 1783ndash17852003

[4] C E Mackintosh J A Maldonado M G Ikonomou and F AP C Gobas ldquoSorption of phthalate esters and PCBs in a marineecosystemrdquo Environmental Science and Technology vol 40 no11 pp 3481ndash3488 2006

[5] M Clara G Windhofer W Hartl et al ldquoOccurrence of phtha-lates in surface runoff untreated and treated wastewater andfate during wastewater treatmentrdquo Chemosphere vol 78 no 9pp 1078ndash1084 2010

[6] M M Abdel Daiem J Rivera-Utrilla R Ocampo-Perez J DMendez-Dıaz andM Sanchez-Polo ldquoEnvironmental impact ofphthalic acid esters and their removal fromwater and sedimentsby different technologiesmdasha reviewrdquo Journal of EnvironmentalManagement vol 109 pp 164ndash178 2012

[7] L Chen Y Zhao L Li B Chen and Y Zhang ldquoExposureassessment of phthalates in non-occupational populations inChinardquo Science of the Total Environment vol 427-428 pp 60ndash69 2012

[8] M J Teil M Blanchard andM Chevreuil ldquoAtmospheric fate ofphthalate esters in an urban area (Paris-France)rdquo Science of theTotal Environment vol 354 no 2-3 pp 212ndash223 2006

[9] P Roslev K Vorkamp J Aarup K Frederiksen and P HNielsen ldquoDegradation of phthalate esters in an activated sludgewastewater treatment plantrdquo Water Research vol 41 no 5 pp969ndash976 2007

[10] J Gasperi S Garnaud V Rocher and R Moilleron ldquoPrioritypollutants in wastewater and combined sewer overflowrdquo Scienceof the Total Environment vol 407 no 1 pp 263ndash272 2008

[11] F Zeng K Cui Z Xie et al ldquoOccurrence of phthalate estersin water and sediment of urban lakes in a subtropical cityGuangzhou South Chinardquo Environment International vol 34no 3 pp 372ndash380 2008

[12] F Zeng K Cui Z Xie et al ldquoPhthalate esters (PAEs) emergingorganic contaminants in agricultural soils in peri-urban areasaround Guangzhou Chinardquo Environmental Pollution vol 156no 2 pp 425ndash434 2008

[13] G Wildbrett ldquoDiffusion of phthalic acid esters from PVC milktubingrdquo Environmental Health Perspectives vol 3 pp 29ndash351973

8 Journal of Analytical Methods in Chemistry

[14] H Fromme T Kuchler T Otto K Pilz J Muller and AWenzel ldquoOccurrence of phthalates and bisphenol A and F inthe environmentrdquoWater Research vol 36 no 6 pp 1429ndash14382002

[15] A D Vethaak J Lahr S M Schrap et al ldquoAn integrated assess-ment of estrogenic contamination and biological effects in theaquatic environment ofTheNetherlandsrdquoChemosphere vol 59no 4 pp 511ndash524 2005

[16] C Dargnat M Blanchard M Chevreuil andM J Teil ldquoOccur-rence of phthalate esters in the Seine River estuary (France)rdquoHydrological Processes vol 23 no 8 pp 1192ndash1201 2009

[17] T Suzuki K Yaguchi S Suzuki and T Suga ldquoMonitoring ofphthalic acid monoesters in river water by solid-phase extrac-tion and GC-MS determinationrdquo Environmental Science andTechnology vol 35 no 18 pp 3757ndash3763 2001

[18] S Y Yuan C Liu C S Liao and B V Chang ldquoOccurrenceand microbial degradation of phthalate esters in Taiwan riversedimentsrdquo Chemosphere vol 49 no 10 pp 1295ndash1299 2002

[19] B Li C Qu and J Bi ldquoIdentification of trace organic pollutantsin drinking water and the associated human health risks inJiangsu Province Chinardquo Bulletin of Environmental Contami-nation and Toxicology pp 1ndash5 2012

[20] F Wang X Xia and Y Sha ldquoDistribution of phthalic acidesters in Wuhan section of the Yangtze River Chinardquo Journalof Hazardous Materials vol 154 no 1ndash3 pp 317ndash324 2008

[21] Y J Sha X H Xia and X Q Xiao ldquoDistribution characters ofphthalic acid ester in the waters middle and lower reaches ofthe Yellow Riverrdquo China Environmental Science vol 26 no 1pp 120ndash124 2006

[22] J Lu L-B Hao C-Z Wang W Li R-J Bai and D YanldquoDistribution characteristics of phthalic acid esters in middleand lower reaches of no 2 Songhua Riverrdquo EnvironmentalScience amp Technology vol 12 article 014 2007

[23] X J Zhu and Y Y Qiu ldquoMeasuring the phthalates of xiangjiangriver using liquid-liquid extraction gas chromatographyrdquoAdvanced Materials Research vol 301 pp 752ndash755 2011

[24] B L Yuan X Z Li and N Graham ldquoAqueous oxida-tion of dimethyl phthalate in a Fe(VI)-TiO

2

-UV reaction sys-temrdquoWater Research vol 42 no 6-7 pp 1413ndash1420 2008

[25] Z Yunrui ZWanpeng L FudongW Jianbing and Y ShaoxialdquoCatalytic activity of RuAl2O3 for ozonation of dimethylphthalate in aqueous solutionrdquo Chemosphere vol 66 no 1 pp145ndash150 2007

[26] H N Gavala U Yenal and B K Ahring ldquoThermal andenzymatic pretreatment of sludge containing phthalate estersprior tomesophilic anaerobic digestionrdquoBiotechnology and Bio-engineering vol 85 no 5 pp 561ndash567 2004

[27] Y Guo Q Wu and K Kannan ldquoPhthalate metabolites in urinefrom China and implications for human exposuresrdquo Environ-ment International vol 37 no 5 pp 893ndash898 2011

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 210653 8 pageshttpdxdoiorg1011552013210653

Research ArticleSimultaneous Determination of Hormonal Residuesin Treated Waters Using Ultrahigh Performance LiquidChromatography-Tandem Mass Spectrometry

Rayco Guedes-Alonso Zoraida Sosa-Ferrera and Joseacute Juan Santana-Rodriacuteguez

Departamento de Quımica Universidad de Las Palmas de Gran Canaria 35017 Las Palmas de Gran Canaria Spain

Correspondence should be addressed to Jose Juan Santana-Rodrıguez jsantanadquiulpgces

Received 28 December 2012 Accepted 7 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Rayco Guedes-Alonso et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

In the last years hormone consumption has increased exponentially Because of that hormone compounds are considered emergingpollutants since several studies have determinted their presence in water influents and effluents of wastewater treatment plants(WWTPs) In this study a quantitative method for the simultaneous determination of oestrogens (estrone 17120573-estradiol estriol17120572-ethinylestradiol and diethylstilbestrol) androgens (testosterone) and progestogens (norgestrel andmegestrol acetate) has beendeveloped to determine these compounds in wastewater samples Due to the very low concentrations of target compounds in theenvironment a solid phase extraction procedure has been optimized and developed to extract and preconcentrate the analytesDetermination and quantification were performed by ultrahigh performance liquid chromatography-tandem mass spectrometry(UHPLC-MSMS) The method developed presents satisfactory limits of detection (between 015 and 935 ngsdotLminus1) good recoveries(between 73 and 90 for the most of compounds) and low relative standard deviations (under 84) Samples from influents andeffluents of two wastewater treatment plants of Gran Canaria (Spain) were analyzed using the proposed method finding severalhormones with concentrations ranged from 5 to 300 ngsdotLminus1

1 Introduction

In general it is supposed that more than 100000 differentchemical compounds can be introduced in the Environmentmany of them in very small quantity However a lot of thesecompounds are not included as pollutants in the legislationAlthough these compounds named emerging pollutants arenot regulated as pollutants they probably will be in the futurebecause of their potential negative effect in the ecosystem For20 years many articles have reported the presence of theseldquonew compoundsrdquo in wastewater [1 2]

The emerging pollutant origin is mainly anthropogenicconsidering that the majority of these compounds are bio-logically active substances that are synthesized to use themin agriculture industry and medicine The main source ofthese emerging pollutants is the residual urbanwaters and thewastewater treatment plants effluents because many of these

WWTPs are not designed or optimized to treat this kind ofcompounds [3]

Hormones are one of the most potent endocrine disrupt-ing compounds as well as are considered also as emergingpollutants Hormones can be differentiated in oestrogensandrogens and progestogens Some of them have limits intheir use but not a specific legislation [4]

The main characteristic of these pollutants is that it isnot necessary to remain in the environment to cause negativeeffects in view of the fact that their constant introduction init offsets their removal or degradation [5]

The steroid hormones help controlling the metabolisminflammations immunological functions water and salt bal-ance sexual development and the capacity of withstandingillnesses [6] The term steroid can be used for naturalhormones produced by the body as well as for artificiallyproduced medicines that increase the natural steroid effect

2 Journal of Analytical Methods in Chemistry

In the last 50 years the natural and synthetic hormoneworldwide consumption has grown as much as in humanmedicine as in cattle farming and they become the mostprescribed medicines [7]

A significant quantity of consumed oestrogens leaves theorganism through excretions For example 17120573-estradiol (E2)is oxidized rapidly becoming an estrone (E1) that can turninto estriol afterwards (E3) Besides the 17120572-ethinyl estradiol(EE) is excreted as conjugated [8]

With regard to emission sources in the first place arethe wastewater treatment plants (WWTPs) [9] and secon-darily cattle waste such as those leachates from dung anduncontrolled dumping [10] Several studies made in theWWTPs have reported that the treatment plants are capableof eliminating around 60 of hormones [11ndash13]

The identification of hormone residues in environmentis of special interest because knowledge of these compoundsis a requirement to take measures in order to regulate andminimize their environmental impact

However measurement of hormone residues is a verydifficult task not only due to the difficulty in measuringvery low concentration but also due to a very complexityof the samples Therefore use of mass spectrometer (MS)as detector coupled with chromatography techniques hasbecome a powerful method for the analysis of these typesof compounds at trace levels [14ndash17] Consequently LC-MSMS is the principally chosen technique One of the mainadvantages of LC-MSMS is its ability to analyze hormoneswithout derivatization (necessary in GC) or the need ofhydrolyze the conjugated form

Due to low level concentration of these compounds inenvironmental water it is necessary to apply an extractionand preconcentration method prior to LC analysis The mostused technique of extraction and preconcentration methodfor liquid samples is the solid phase extraction (SPE) [18ndash20]

The objective of this study is to develop a rapid and simpleprocedure of extraction preconcentration and determina-tion of four steroid oestrogens (estrone (E1) 17120573-estradiol(E2) estriol (E3) and 17120572-ethinylestradiol (EE)) one non-steroidal oestrogen the diethylstilbestrol (DES) one andro-gen the testosterone (TES) and two synthetic progestogensnorgestrel (NOR) and megestrol acetate (MGA) (Table 1)based on solid phase extraction and ultrahigh performanceliquid chromatography-tandem mass spectrometry (SPE-UHPLC-MSMS) The developed method was applied tothe identification and quantification of these compoundsin wastewater samples obtained from the influents andeffluents of two wastewater treatment plants (WWTPs) ofGran Canaria (Spain) They presented different methodsof wastewater treatments WWTP 1 presented a traditionalmethod based on activated sludge while WWTP 2 used amembrane bioreactor technique

2 Materials and Methods

21 Reagents All of the hormonal compounds usedwere pur-chased from Sigma-Aldrich (Madrid Spain) Stock solutionscontaining 1000mgsdotLminus1 of each analyte were prepared by

dissolving the compound inmethanol and the solutionswerestored in glass-stoppered bottles at 4∘C prior to use Workingaqueous standard solutions were prepared daily Ultrapurewater was provided by a Milli-Q system (Millipore BedfordMA USA) HPLC-grade methanol LC-MS methanol andLC-MS water as well as the ammonia and the ammoniumacetate used to adjust the pH of the mobile phases wereobtained from Panreac Quımica (Barcelona Spain)

22 Sample Collection Water samples were collected fromthe effluents of twowastewater treatment plants located in thenorthern area of Gran Canaria in May and August of 2012WWTP 1 used a conventional activated sludge treatmentsystem while WWTP 2 employed a membrane bioreactortreatment system The samples were collected in 2 L amberglass bottles that were rinsed beforehand with methanol andultrapurewater Samples were purified through filtrationwithfibreglass filters and then with 065 120583m membrane filters(Millipore Ireland) The samples were stored in the dark at4∘C and extracted within 48 hours

23 Instrumentation For the SPE optimization the instru-ment used was an ultrahigh performance liquid chromatog-raphy with fluorescence detector (UHPLC-FD) system con-sisting of an ACQUITYQuaternary Solvent Manager (QSM)used to load samples and wash and recondition the analyticalcolumn an autosampler a column manager and a fluores-cence detector with excitation and emission wavelengths of280 and 310 nm respectively all fromWaters (Madrid Spain)

The analysis of wastewater samples was performed ina UHPLC-MSMS system from Waters (Madrid Spain)similar to the described above with a 2777 autosamplerequipped with a 25120583L syringe and a tray to hold 2mLvials and an ACQUITY tandem triple quadrupole (TQD)mass spectrometer with an electrospray ionization (ESI)interface All Waters components (Madrid Spain) werecontrolled using the MassLynx Mass Spectrometry SoftwareElectrospray ionisation parameters were fixed as followsthe capillary voltage was 3 kV in positive mode and minus2 kVin negative mode the source temperature was 150∘C thedesolvation temperature was 500∘C and the desolvation gasflow rate was 1000 Lhr Nitrogen was used as the desolvationgas and argon was employed as the collision gas

The detailed MSMS detection parameters for each hor-monal compound are presented in Table 2 and were opti-mised by the direct injection of a 1mgsdotLminus1 standard solutionof each analyte into the detector at a flow rate of 10 120583Lsdotminminus1

24 Chromatographic Conditions For the SPE optimizationthe analytical column was a 50mm times 21mm ACQUITYUHPLCBEHWaters C

18columnwith a particle size of 17120583m

(Waters Chromatography Barcelona Spain) operating at atemperature of 30∘C Analytes separation was carried outemploying the following gradient starting at 55 45 (vv)water methanol for 1 minute During 3 minutes it changedto 50 50 (vv) and stayed for 25 minutes more Finally cameback to initial conditions in 1 minute and stayed for 15

Journal of Analytical Methods in Chemistry 3

Table 1 List of hormonal compounds pKa values chemical structure and retention times

Compound pKa [21] Structure 119905119877

(min)

E3 Estriol 103

HO

OH

OH

H H

H096

E2 17120573-estradiol 103

HO

OH

H H

H218

EE 17120572-ethinylestradiol 103

HO

HO

H H

H223

E1 Estrone 103

HO

O

H

H H220

DES Diethylstilbestrol 102

HO

OH

235

TES Testosterone 151

OH

OH H

H240

MGA Megestrol acetate

O

O

O

OH

H

H306

NOR Levonorgestrel 131

OH

O

H

H

H

H263

minutes Therefore the analysis took 9 minutes at a flow of05mLsdotminminus1

For the analysis of real samples aUHPLC-MSMS systemwas used The analytical column was the same and themobile phase was water and methanol adjusted with a bufferconsisting in 01 vv ammonia and 15mM of ammoniumacetate The analysis was performed in gradient mode at aflow rate of 03mLsdotminminus1The gradient started at 50 50 (vv)mixture of water methanol which changed to 25 75 (vv) in3 minutes and returned to 50 50 in 1 minute more Finallythe gradient stayed calibrating for another 15 minutes moreThe sample volume injected was 5120583L

3 Results and Discussion

31 Optimization of Solid-Phase Extraction (SPE) There area number of parameters that affect SPE procedure such as

type of sorbent pH ionic strength sample and desorptionvolumes and wash step To optimize these parameters itused Milli-Q water spiked with a solution of fluorescenceoestrogens (estriol 17120573-estradiol and 17120572-ethinylestradiol)to obtain a final concentration of 250120583gsdotLminus1

The first parameter to optimize is the choice of sorbentsince it controls the selectivity affinity and capacity overanalytes In this study the SPE cartridges used were OASISHLB SepPak C

18(both from Waters Madrid Spain) and

BondElut ENV (fromAgilent Madrid Spain) Keeping otherparameters fixed (ionic strength of 0 sample volume of100mL) the cartridges were studied at three different pHs(5 8 and 11) From the results obtained it can be observedthat the better signals are found for SepPak C

18cartridge

(Figure 1)After choosing the optimum cartridge we used an initial

experimental design of 23 to study the influence of pH ionic

4 Journal of Analytical Methods in Chemistry

Table 2 Mass spectrometer parameters for the determination of target analytes

Compound Precursor ion(mz)

Capillary voltage(Ion mode)

Quantification ionmz(collision potential V)

Quantification ionmz(collision potential V)

E3 2872 minus65V (ESI minus) 1710 (37) 1452 (39)E2 2712 minus65V (ESI minus) 1451 (40) 1831 (31)EE 2952 minus60V (ESI minus) 1450 (37) 1589 (33)E1 2692 minus65V (ESI minus) 1450 (36) 1430 (48)DES 2671 minus50V (ESI minus) 2371 (29) 2511 (25)TES 2892 38V (ESI +) 1870 (18) 1040 (21)MGA 3855 30V (ESI +) 2673 (15) 2242 (30)NOR 3132 38V (ESI +) 1090 (26) 2451 (18)

0

500

1000

1500

2000

2500

E3 E2 EE

Peak

area

Cartridge optimizationOASIS HLB pH = 5

OASIS HLB pH = 8

OASIS HLB pH = 11SepPak C18 pH = 5

SepPak C18 pH = 8

SepPak C18 pH = 11BondElut ENV pH = 5

BondElut ENV pH = 8

BondElut ENV pH =11

Figure 1 Optimization of SPE cartridges

strength and sample volume over extraction process Theexperimental design was obtained using Statgraphics Plussoftware 51 and the statistics study was done with IBM SPSSStatistics 19 We assessed two levels and three parameters pH(3 and 8) ionic strength (0 and 30 of NaCl) and samplevolume (50 and 250mL) to obtain the influence of eachparameter and the variable correlation to each other In thisstudy it is observed that the ionic strength and sample volumehad the major influence on the recoveries of the analytesFor that a 32 factorial design to optimize these two variablesat three levels per parameter (0 15 and 30 of NaCl forionic strength and 50 100 y 250mL for sample volume) wasused Figure 2 shows the response surface obtained for theestriol and 17120572-ethinylestradiol The results obtained showedthat an increment of the ionic strength did not producean increase in the response area of the compound and theoptimum volume was 250mL Because of that a solutionwithout salt addition and 250mL of sample volume waschosen Finally the desorption volume (1mLofmethanol and2mL of methanol in one and two steps) and wash-step (5mL

ofMilli-Q water and 5mL ofMilli-Q water with 5 and 10 ofmethanol vv) were assayed to complete the optimization ofthe SPE process The optimum values were 2mL of methanolin one step and 5mL of Milli-Q water without methanolrespectively

In accordance with the obtained results the optimumconditions for SPE procedure were SepPak C

18cartridge

250mL of sample at pH = 8 and 0 of NaCl desorptionwith 2mL of methanol in one step and wash step with5mL of Milli-Q water In these conditions we achieved apreconcentration factor of 125 In Figure 3 a chromatogramwith the optimum conditions is shown where the peaksof all compounds in their corresponding transitions can beobserved

32 Analytical Parameters Because of the SPE optimizationthat was done only with fluorescent compounds (estriol 17120573-estradiol and 17120572-ethinylestradiol) it was necessary to studythe recoveries of all the hormonal compounds using theoptimized SPE-UHPLC-MSMSmethod All the compoundsunder study showed good recoveries over 73 except thediethylstilbestrol with a recovery of 507

A calibration curve was used for the quantification ofthe analytes by diluting the stock solution of each analyteinto the samples to concentrations ranging between 1 and100 120583gsdotLminus1 Analysis was conducted by UHPLC-MSMS andlinear calibration plots for each analyte (1199032 gt 099) wereobtained based on their chromatographic peak areas

The limit of detection (LOD) and the limit of quantifi-cation (LOQ) for each compound were calculated from thesignal-to-noise ratio of each individual peak The LOD wasdefined as the lowest concentration that gave a signal-to-noiseratio that was greater than 3 The LOQ was defined as thelowest concentration that gave a signal to noise ratio that wasgreater than 10The LODs ranged from015 to 935 ngsdotLminus1 andthe LOQs ranged from 049 to 3118 ngsdotLminus1

The performance and reliability of the process werestudied by determining the repeatability of the quantificationresults for all target analytes under the described conditionsusing six samples (119899 = 6) The relative standard deviations(RSDs) were lower than 84 in all cases indicating a

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 6: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Contents

Analysis and Fate of Emerging Pollutants during Water Treatment Fei Qi Guang-Guo Ying Kaimin ShihJolanta Kumirska Elif Pehlivanoglu-Mantas and Xiaojun LuoVolume 2013 Article ID 256956 1 page

Occurrence and Removal Characteristics of Phthalate Esters from Typical Water Sources in NortheastChina Yu Liu Zhonglin Chen and Jimin ShenVolume 2013 Article ID 419349 8 pages

Simultaneous Determination of Hormonal Residues in Treated Waters Using Ultrahigh PerformanceLiquid Chromatography-Tandem Mass Spectrometry Rayco Guedes-Alonso Zoraida Sosa-Ferreraand Jose Juan Santana-RodrıguezVolume 2013 Article ID 210653 8 pages

Removal Efficiency and Mechanism of Sulfamethoxazole in Aqueous Solution by Bioflocculant MFXJie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei WeiVolume 2013 Article ID 568614 8 pages

Pyrite Passivation by Triethylenetetramine An Electrochemical Study Yun Liu Zhi Dang Yin Xuand Tianyuan XuVolume 2013 Article ID 387124 8 pages

A Green Preconcentration Method for Determination of Cobalt and Lead in Fresh Surface and WasteWater Samples Prior to Flame Atomic Absorption Spectrometry Naeemullah Tasneem Gul KaziFaheem Shah Hassan Imran Afridi Sumaira Khan Sadaf Sadia Arian and Kapil Dev BrahmanVolume 2012 Article ID 713862 8 pages

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 256956 1 pagehttpdxdoiorg1011552013256956

EditorialAnalysis and Fate of Emerging Pollutants duringWater Treatment

Fei Qi1 Guang-Guo Ying2 Kaimin Shih3 Jolanta Kumirska4

Elif Pehlivanoglu-Mantas5 and Xiaojun Luo2

1 Beijing Key Lab for Source Control Technology of Water Pollution College of Environmental Science and EngineeringBeijing Forestry University No 35 Qinghua East Road Beijing 100083 China

2 State Key Laboratory of Organic Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of SciencesGuangzhou 510640 China

3Department of Civil Engineering The University of Hong Kong Pokfulam Road Hong Kong4Department of Environmental Analysis Faculty of Chemistry University of Gdansk Sobieskiego 1819 80-952 Gdansk Poland5 Environmental Engineering Department Istanbul Technical University Ayazaga Campus Maslak 34469 Istanbul Turkey

Correspondence should be addressed to Fei Qi qifeibjfueducn

Received 23 April 2013 Accepted 23 April 2013

Copyright copy 2013 Fei Qi et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Emerging pollutants defined as compounds that are notcurrently covered by existing water-quality regulations allover the world have not been studied widely before and arethought to be potential threats to environmental ecosystemsand human health This special issue compiles 5 excitingpapers which are very meticulously performed researches

Generally emerging pollutants encompass a diversegroup of compounds including pharmaceuticals drugs ofabuse personal-care products (PCPs) steroids and hor-mones surfactants perfluorinated compounds (PFCs) flameretardants industrial additives and agents gasoline additivesnew disinfection byproducts (DBPs) nanomaterials and thetoxic minerals

The analysis methods occurrence and fate of hormonaland endocrine disruptors compounds (EDCs) were dis-cussed in two papers of this special issue R Guedes-Alonsoet al determine the hormonal residues in treated water byultrahigh performance liquid chromatography-tandem massspectrometry (UPLC-MS) and evaluate the efficiency ofthe conventional wastewater treatment for the removal ofhormonal compounds Moreover Y Liu et al study anotherkinds of PPCPs named as phthalate esters that is typicalkind of EDCs The occurrence in a surface water and theremoval efficiency in a traditional drinking water treatmentpalnt are studied According to results of the two papers

the occurrence and fate of hormonal and EDCs in water orwastewater treatment are very clear

J Xing et al report a new wastewater treatment technol-ogy bioflocculation for the removal of sulfamethoxazole thatis a typical pharmaceutical in wastewater The performanceand the reaction mechanism of the biodegradation of sul-famethoxazole by the bioflocculation are discussed in depthMoreover the optimum reaction condition is obtained

The heavy metal and toxic mineral are also importantpollutants in the environment especially in the mining areaTwo papers of this issue are focused on this K Naeemul-lah et al report a green preconcentration method for thedetermination of cobalt and lead in water Y Liu et al do anovel research on the electrochemical reaction of pyrite as asimulation of the natural environmental

By compiling this special issue we hope to enrich ourreaders and researchers on the analysis and fate of emergingpollutants during water treatment

Fei QiGuang-Guo Ying

Kaimin ShihJolanta Kumirska

Elif Pehlivanoglu-MantasXiaojun Luo

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 419349 8 pageshttpdxdoiorg1011552013419349

Research ArticleOccurrence and Removal Characteristics of Phthalate Estersfrom Typical Water Sources in Northeast China

Yu Liu Zhonglin Chen and Jimin Shen

State Key Laboratory of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Jimin Shen shenjiminhiteducn

Received 21 December 2012 Accepted 3 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Yu Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The presence of phthalate esters (PAEs) in the environment has gained a considerable attention due to their potential impactson public health This study reports the first data on the occurrence of 15 PAEs in the water near the Mopanshan Reservoirmdashthenew and important water source of Harbin city in Northeast China As drinking water is a major source for human exposureto PAEs the fate of target PAEs in the two waterworks (Mopanshan Waterworks and Seven Waterworks) was also analyzed Theresults demonstrated that the total concentrations of 15 PAEs in the water near the Mopanshan Reservoir were relatively moderateranging from 3558 to 92265 ngL with the mean value of 29431 ngL DBP and DEHP dominated the PAE concentrations whichranged from 525 to 44982 ngL and 1289 to 65709 ngL respectivelyThe occurrence and concentrations of these compoundswereheavily spatially dependent Meanwhile the results on the waterworks samples suggested no significant differences in PAE levelswith the input of the raw waters Without effective and stable removal of PAEs after the conventional drinking water treatment inthe waterworks (258 to 765) the risks posed by PAEs through drinking water ingestion were still existing which should bepaid special attention to the source control in theMopanshan Reservoir and some advanced treatment processes for drinking watersupplies

1 Introduction

Phthalate acid esters a class of chemical compounds mainlyused as plasticizers for polyvinyl chloride (PVC) or to alesser extent other resins in different industrial activities areubiquitous in the environment and have evoked interest inthe past decade due to endocrine disrupting effects and theirpotential impacts on public health [1ndash3]

Worldwide production of PAEs is approximately 6 mil-lion tons per year [4] As PAEs are not chemically boundto the polymeric matrix in soft plastics they can enter theenvironment by losses during manufacturing processes andby leaching or evaporating from final products [5]Thereforethe occurrence and fate of specific PAEs in natural waterenvironments have been observed and also there are a lot ofconsiderable controversies with respect to the safety of PAEsin water [5ndash10]

Six PAE compounds including dimethyl (DMP) diethyl(DEP) dibutyl (DBP) butylbenzyl (BBP) di(2-ethylhexyl)

(DEHP) and di-n-octyl phthalate (DNOP) are classifiedas priority pollutants by the US Environmental ProtectionAgency (EPA) Though the toxicity of PAEs to humans hasnot been well documented for some years the Ministry ofEnvironmental Protection in China has regulated phthalatesas environmental pollutants In addition the standard inChina concerning analytical controls on drinkingwaters doesnot specifically identify any PAEs as organic pollutant indexesto be determined by the new drinking water standard in 2007(Standard for drinking water quality GB5749-2006) whichwas forced to be monitored for the drinking water supplies in2012 Consequently official data about the presence of thesepollutants in the aquatic environment of some cities are notavailable

Harbin the capital of Heilongjiang Province is a typicallyold industrial base and economically developed city with apopulation of over 3million inNortheast China As the newlyenabledwater source forHarbin cityMopanshanwaterworkssupply the whole city with drinking water through long

2 Journal of Analytical Methods in Chemistry

China

HarbinMopanshan

Reservoir

LongfengshanReservoir

Figure 1 Spatial distribution of the 16 sampling sites near the Mopanshan Reservoir in Northeast China

distance transfer from the Mopanshan Reservoir To theauthorsrsquo knowledge the occurrence and fate of PAEs in thewater near this area and its relative waterworks have notpreviously been examined

The objectives of this study were (i) to determine theoccurrence of PAEs and clarify the fate and distribution ofthe pollutants in the water source (ii) to examine the twowaterworks where traditional drinking water treatment stepwas evaluated on the PAEs removal efficiencies and (iii) toevaluate the potential for adverse effects of PAEs on humanhealth Therefore the investigation of PAEs in the water canprovide a valuable record of contamination in Harbin city

2 Materials and Methods

21 Chemical Fifteen PAEs standard mixture includingdimethyl phthalate diethyl phthalate diisobutyl phthalatedi-n-butyl phthalate di(4-methyl-2-pentyl) phthalate di(2-ethoxyethyl) phthalate di-n-amyl phthalate di-n-hexylphthalate butyl benzyl phthalate di(hexyl-2-ethylhexyl)phthalate di(2-n-butoxyethyl) phthalate dicyclohexyl phthal-ate di(2-ethylhexyl) phthalate di-n-nonyl phthalate di-n-octylphthalate at 1000 120583gmL each and surrogate standardsconsisting of diisophenyl phthalate di-n-phenyl phthal-ate and di-n-benzyl phthalate in a mixture solution of500120583gmL each were supplied by AccuStandard Inc Asthe internal standard benzyl benzoate was also purchasedfrom AccuStandard Inc All solvents (acetone hexane anddichloromethane) used were HPLC-grade and were pur-chased from J T Baker Co (USA) Anhydrous sodiumsulfate (Tianjin Chengguang Chemical Reagent Co China)was cleaned at 600∘C for 6 h and then kept in a desiccatorbefore use

22 Sample Collection and Preparation Harbin the capitalof Heilongjiang province in China imports nearly all of itsdrinking water from two sources the Mopanshan Reservoir

Raw water Coagulation sedimentation Filtration Tank

Sampling site Sampling site

Figure 2 Schematic diagram of the waterworks

(long-distance transport project) and the Songhua River (oldwater source)

Water samples from the Mopanshan Reservoir andMopanshan waterwork were collected in 2008 The locationsof the sampling sites near the Mopanshan Reservoir are pre-sented in Figure 1 as a comparison sampling from anotherHarbin water supplymdashSeven waterworks with water sourcefrom the SonghuaRiverwas performed in 2011 In eachwater-works with considering the hydraulic retention time threesets of raw water samples (influent) were taken and thenthe final finished waters (effluent) after the whole treatmentprocess were carried out for the collectionsThe flow diagramof the waterworks is shown in Figure 2

Samples were collected using 20 L glass jars from 05mbelow the water surface During the whole sampling processthe global position system was used to locate the samplingstations (details in Table 1) All samples were transferred tothe laboratory directly after sampling and stored at 4∘C priorto extraction within 2 d

Water samples were filtered under vacuum through glassfiber filters (07 120583mpore sizes) Prior to extraction each sam-ple was spiked with surrogate standards The water sampleswere extracted based on a classical liquid phase extractionmethod (USEPA method 8061) with slight modificationsBriefly 1 L of water samples was placed in a separating funneland extracted by means of mechanical shaking with 150mLdichloromethane and then with filtration on sodium sulfate(about 20 g) the organic extracts were concentrated usinga rotary evaporator The exchange of solvent was done byreplacing dichloromethane with hexane Finally they were

Journal of Analytical Methods in Chemistry 3

Table 1 Detailed descriptions of the sampling locations

Number Sampling site Name Latitude Longitude1 Lalin Jinsan Bridge Mangniu River E127∘0210158405310158401015840 N45∘510158404510158401015840

2 Xingsheng Town Gaojiatun Lalin River E127∘0610158401110158401015840 N44∘5110158405710158401015840

3 Dujia Town Shuguang Lalin River E127∘1010158404410158401015840 N44∘4810158404110158401015840

4 Shanhe Town Taipingchuan Lalin River E127∘1810158403610158401015840 N44∘4310158405010158401015840

5 Xiaoyang Town Qichuankou Lalin River E127∘2310158405410158401015840 N44∘3910158404610158401015840

6 Shahezi Town Mopanshan Reservoir E127∘3810158405910158401015840 N44∘2410158401710158401015840

7 Shahezi Town Gali Lalin River E127∘3510158401710158401015840 N44∘3110158405610158401015840

8 Chonghe Town Changcuizi Mangniu River E127∘4610158403610158401015840 N44∘3510158404610158401015840

9 Chonghe Town Xingguo Mangniu River E127∘3510158401710158401015840 N44∘3110158405710158401015840

10 Longfeng Town Mangniu River E127∘3510158401910158401015840 N44∘4310158404810158401015840

11 Changpu Town Zhonghua Mangniu River E127∘1610158403010158401015840 N45∘110158404210158401015840

12 Erhe Town Shuanghe Mangniu River E127∘1810158403210158401015840 N45∘410158402810158401015840

13 Zhiguang Town Songjiajie Mangniu River E127∘341015840310158401015840 N45∘110158402010158401015840

14 Zhiguang Town Wuxing Mangniu River E127∘2910158402010158401015840 N45∘010158404310158401015840

15 Changpu Town Xingzhuang Mangniu River E127∘1010158404210158401015840 N45∘410158403610158401015840

16 Yingchang Town Xingguang Lalin River E126∘551015840810158401015840 N45∘91015840010158401015840

reduced to 05mL under gentle nitrogen flow The internalstandard was added to the sample prior to instrumentalanalysis

23 Chemical Analysis The extracted compounds weredetermined by gas chromatography coupled to mass spec-trometer analysis as described in other publications [1112] Briefly extracted samples were injected into an Agilent6890 Series GC equipped with a DB-35MS capillary column(Agilent 30m times 025mm id 025120583m film thickness) andan Agilent 5973 MS detector operating in the selective ionmonitoring mode The column temperature was initially setat 70∘C for 1min then ramped at 10∘Cmin to 300∘C andheld constant for 10min The transfer line and the ion sourcetemperature were maintained at 280 and 250∘C respectivelyHelium was used as the carrier gas at a flow rate of 1mLminThe extracts (20 120583L) were injected in splitless mode with aninlet temperature of 300∘C

24 Quality Assurance and Quality Control All glasswarewas properly cleaned with acetone and dichloromethanebefore use Laboratory reagent and instrumental blanks wereanalyzed with each batch of samples to check for possiblecontamination and interferences Only small levels of PAEswere found in procedural blanks in some batches andthe background subtraction was appropriately performed inthe quantification of concentration in the water samplesCalibration curves were obtained from at least 3 replicateanalyses of each standard solution The surrogate standardswere added to all the samples to monitor matrix effectsRecoveries of PAEs ranged from 62 to 112 in the spikedwater and the surrogate recoveries were 751 plusmn 127 fordiisophenyl phthalate 723 plusmn 143 for di-n-phenyl phtha-late and 1026 plusmn 104 for di-n-benzyl phthalate in thewater samples The determination limits ranged from 6 to30 ngL A midpoint calibration check standard was injected

as a check for instrumental drift in sensitivity after every10 samples and a pure solvent (methanol) was injected as acheck for carryover of PAEs from sample to sample All theconcentrations were not corrected for the recoveries of thesurrogate standards

3 Results and Discussion

31 PAEs in Water Source The PAEs in the waters fromthe sampling sites near the Mopanshan Reservoir wereinvestigated and the results are presented in Table 2 Thesum15

PAEs concentrations ranged from 3558 to 92265 ngLwith the geometric mean value of 29431 ngL Among the15 PAEs detected in the waters DIBP DBP and DEHP weremeasured in all the samples with the average concentrationsbeing 1966 8014 and 17741 ngL respectively The threePAE congeners are important and popular addictives inmany industrial products including flexible PVC materialsand household products suggesting the main source of PAEcontaminants in the water [13] The correlations of the con-centration of DEHP DBP and DIBP with the concentrationsof total PAEs in the water samples are shown in Figure 3and a relatively significant correlation between sum

15

PAEs andDEHP concentration was found suggesting the importantpart played by DEHP in total concentrations of PAEs inthe water bodies near the Mopanshan Reservoir In otherwords the contribution of DEHP to total PAEs was higherthan that of other PAE congeners in the water samples Inaddition DMP DEP and DNOP with the mean value of140 284 and 541 ngL respectively only detected at somesampling sites and have also attracted much attention asthe priority pollutants by the China National EnvironmentalMonitoring Center On the contrary the concentrations of6 PAEs (DMEP BMPP BBP DBEP DCHP and DNP) werebelow detection limits in all the water samples near theMopanshan Reservoir which is easily explained in terms ofmuch lower quantities of present use in China

4 Journal of Analytical Methods in Chemistry

0 2000 4000 6000 80000

2000

4000

6000

Con

cent

ratio

ns (n

gL)

DEHP

119903 = 0885 119875 lt 001

sum15PAEs (ngL)

(a)

0 2000 4000 6000 80000

2000

4000

Con

cent

ratio

ns (n

gL)

sum15PAEs (ngL)

DBP

119903 = 0812 119875 lt 001

(b)

1000

500

0

0 2000 4000 6000 8000sum15PAEs (ngL)

DIBP

Con

cent

ratio

ns (n

gL)

119903 = 0724 119875 lt 001

(c)

Figure 3 Correlations of the concentration of the major PAEs (DEHP DBP and DIBP) with the concentrations of total PAEs in the watersamples

Table 2 Concentrations of 15 PAEs in water samples near the Mopanshan Reservoir

PAEs Abbreviation Water (ngL)Range Mean Frequency

Dimethyl phthalate DMP ndndash424 140 816Diethyl phthalate DEP ndndash550 284 1516Diisobutyl phthalate DIBP 400ndash6588 1966 1616Dibutyl phthalate DBP 525ndash44982 8014 1616bis(2-methoxyethyl)phthalate DMEP nd nd 016bis(4-methyl-2-pentyl)phthalate BMPP nd nd 016bis(2-ethoxyethyl)phthalate DEEP ndndash546 128 516Dipentyl phthalate DPP ndndash925 455 1016Dihexyl phthalate DHXP ndndash651 162 516Benzyl butyl phthalate BBP nd nd 016bis(2-n-butoxyethyl)phthalate DBEP nd nd 016Dicyclohexyl phthalate DCHP nd nd 016bis(2-ethylhexyl)phthalate DEHP 1289ndash65709 17741 1616Di-n-octyl phthalate DNOP ndndash4482 541 516Dinonyl phthalate DNP nd nd 016sum15

PAEs 3558ndash92265 29431 mdash

The distribution of 15 PAEs (sum15

PAEs) studied and6 US EPA priority PAEs (sum

6

PAEs including DMP DEPDIBP DBP DEHP and DNOP) in the waters from differentsampling sites are shown in Figure 4 There was an obviousvariation in the total sum

15

PAEs concentrations in water sam-ples near the Mopanshan Reservoir the concentrations ofsum6

PAEs from the same sampling sites varied from 2690 to90860 ngL with an average of 28686 ngL the distributionspectra of which observed for all the sampling sites weresimilar tosum

15

PAEsThe highest levels of PAEs contaminationwere seen on the sampling site 3 followed by some relativelyheavily polluted sites (site 16 13 9 10 and 11) indicating thatthese sites served as important PAE sources and the spatialdistribution of PAEs was site specific The levels in the watersexamined varied over a wide range especially in theMangniu

River near theMopanshan Reservoir (in some case overmorethan one order of magnitude) In general it should be notedthat there might be a relation of PAEs levels with the input oflocal waste such as sewage water food packaging and scrapmaterial near the sampling point which were found duringthe sampling period

32 PAE Congener Profiles in the Water Different PAE pat-terns may indicate different sources of PAEs Measurementof the individual PAE composition is helpful to track thecontaminant source and demonstrate the transport and fateof these compounds in water [11] The relative contributionsof the 9 detectable PAE congeners to thesum

15

PAEs concentra-tions in the water are presented in Figure 5 It is clear thatDEHP was the most abundant in the water samples with

Journal of Analytical Methods in Chemistry 5

0

500

1000

1500

4000

6000

8000

10000

Con

cent

ratio

ns (n

gL)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

sum15PAEssum6PAEs

Figure 4 Spatial distributions of the 16 sampling sites near theMopanshan Reservoir

the exception of site 2 3 and 11 contributions ranging from331 to 963 followed byDBP ranging from 21 to 363The results are consistent with the above data for overallanalysis that DBP and DEHP are the dominant componentsof the PAEs distribution pattern in each sampling site whichreflected the different pattern of plastic contaminant inputduring the sampling period Similarly DIBP and DBP areused in epoxy resins or special adhesive formulations withthe different proportions of these two PAE congeners whichwere also the important indicator of the information pollutedby PAEs for the sampling locations Although the limitedsample number draws only limited conclusions there is stillreason to note that a leaching from the plastic materials intothe runoff water is possible and that water runoff from thecontaminated water is a burden pathway from differentsources of PAEs [14]

33 Comparison with Other Water Bodies Comparison withthe total PAEs concentrations is nevertheless very limited dueto the different analysis compounds However the individualPAE namely DBP and DEHP is by far the most abundantin other researches and it is possible to make a camparisonwith our findings In this case the results of DBP and DEHPconcentrations published in literatures for kinds of waterbodies are presented together in Table 3

The DEHP and DBP concentrations of the present studyshowed to some extent lower concentration levels than thosereported in the other water bodies in China In comparisonthe results were comparable or similar to those from theexaminations described in other foreign countries For exam-ple as shown in Table 3 the DEHP concentrations were sim-ilar to the surface waters from the Netherlands and Italydescribed in the literature Meanwhile these concentrationsin this study were quite lower than the Yangtze River andSecond Songhua River in China

0

20

40

60

80

100

DEEP DPP DHXP DEHP DNOP DBP

DIBP DEP DMP

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

Com

posit

ion

()

Figure 5 PAE composition of thewater samples in 16 sampling sites

In conclusion as compared to the results of other studiesthe waters near the Mopanshan Reservoir were moderatelypolluted by PAEs Therefore there is a definite need to set upa properly planned and systematic approach to water controlnear the Mopanshan Reservoir

34 PAE Levels in the Waterworks The Mopanshan Water-works (MPSW) equipped essentially with the water sourceof the Mopanshan Reservoir has been investigated in orderto assess the fate of the PAEs during the drinking watertreatment process For comparison a sampling campaign forthe determination of PAEs levels in the Seven Waterworks(SW waterworks with the old water source of the SonghuaRiver) was carried out Both waterworks operate coagulationsedimentation and followed by filtration treatment processwhich are typical traditional drinking water treatment

The measured concentrations in the raw and finishedwater of the two investigated waterworks are shown inFigure 6 Six out of fifteen PAEs were detected in the fin-ished water from the two waterworks The detected PAEswere DMP DEP DIBP DBP DEHP and DNOP and theother investigated phthalates are of minor importance withconcentrations all below the limit of detection As showin Figure 6 the measured concentrations of the analyzedPAEs in the finished water of the two waterworks variedstronglyThemost important compound in the finishedwaterwas DEHP with the mean concentration of 34737 and40592 ngL for the MPSW and SW respectively suggestingthe highest relative composition of total PAE concentrationsin the drinking water

For the raw water from the different water sources DMPand DIBP concentrations in the MPSW were much lowerthan the ones in the SW and the concentrations of DEPDBP DEHP andDEHPwere relatively comparable in the two

6 Journal of Analytical Methods in Chemistry

Table 3 Comparison of the concentrations of DEHP and DBP in the water bodies (ngL)

Location DEHP DBP ReferenceRange Median Mean Range Median Mean

Surface water Germany 330ndash97800 2270 mdash 120ndash8800 500 mdash [14]Surface water the Netherlands ndndash5000 320 mdash 66ndash3100 250 mdash [15]Seine River estuary France 160ndash314 mdash mdash 67ndash319 mdash mdash [16]Tama River Japan 13ndash3600 mdash mdash 8ndash540 mdash mdash [17]Velino River Italy ndndash6400 mdash mdash ndndash44300 mdash mdash [2]Surface water Taiwan ndndash18500 mdash 9300 1000ndash13500 mdash 4900 [18]Surface water Jiangsu China 556ndash156707 mdash mdash 16ndash58575 mdash mdash [19]Yangtze River mainstream China 3900ndash54730 mdash mdash ndndash35650 mdash mdash [20]Middle and lower Yellow River China 347ndash31800 mdash mdash ndndash26000 mdash mdash [21]Second Songhua River China ndndash1752650 370020 mdash ndndash5616800 mdash 717240 [22]Urban lakes Guangzhou China 87ndash630 170 240 940ndash3600 1990 2030 [11]Xiangjiang River China 620ndash15230 mdash mdash mdash mdash mdash [23]This study 1289ndash65709 6710 17741 525ndash44982 1103 8014

0

500

1000

100001200014000

0

20

40

60

80

100

Raw waterFinished waterRemoval

Rem

oval

()

Con

cent

ratio

ns (n

gL)

DMP DEP DIBP DBP DEHP DNOP

(a)

Raw waterFinished waterRemoval

0

500

1000

1500

2000

100001200014000

0

20

40

60

80

100C

once

ntra

tions

(ng

L)

Rem

oval

()

DMP DEP DIBP DBP DEHP DNOP

(b)

Figure 6 PAEs detected in the water samples from the MPSW (a) and SW (b)

waterworks The removal of PAEs by these two waterworksranged from 258 to 765 which varied significantly with-out stable removal efficienciesThe lower removal efficienciesfor DMP and DNOP were observed in the SW with theremoval less than 30 For both the waterworks no soundremoval efficiencies were obtained for the PAEs indicatingthat the traditional drinking water treatment cannot showgood performance to eliminate these micro pollutants whichhas nothing to do with the type of the water source

Traditional drinking water treatment focuses on dealingwith the particles and colloids in terms of physical processesMany studies of the environmental fates of PAEs have demon-strated that oxidation or microbial action is the principalmechanism for their removal in the aquatic systems [24ndash26]Therefore the treatment process should be the combinationswith the key techniques for removing PAEs from the waterOn the other hand since the removal efficiencies of PAEs by

these advance drinking water treatments in waterworks hasnot been systematically studied to date further research inthis direction would seem to be required

35 Exposure Assessment of PAEs in Water To evaluate thepotential and adverse effects of PAEs quality guidelines forsurface water and drinking water standard were used Theresults indicated that the mean concentrations of DBP andDEHP at levels were well below the reference doses (RfD)regarded as unsafe by the EPA for the surface water Thelevels were not also above the RfD recommended by China(Environmental Quality Standard for SurfaceWater of ChinaGB3838-2002) On the other hand the amounts of DEHPpresent in public water supplies should be lower than thedrinkingwater standard (0006mgL for EPA and 0008mgLfor China) According to the results the concentrations of

Journal of Analytical Methods in Chemistry 7

DEHP in drinkingwater samples from theMPSWwere lowerthan the limited value

PAEs are also considered to be endocrine disruptingchemicals (EDCs) whose effects may not appear until long-term exposure According to the results PAEs were detectedin the drinking water constantly ingested in daily life indi-cating that drinking water is an important source of humanexposure to PAEs contaminants Assuming a daily waterconsumption rate of 2 L and an average body weight of 60 kgfor adults the average daily intake of DEHP DBP and DIBPby way of drinking water from MPSW was calculated to be1158 1352 and 81 ngkgd respectively In comparison thevalues of SW with the water source of the Songhua Riverwere relatively higher with the calculated results of 1353140 and 155 ngkgd for DEHP DBP and DIBP respectivelyIn this study the estimated daily intake levels of DEHPfrom the drinking water were quite lower than the RfDof 20000 ngkgd released by the EPA However some ofPAEs are partly metabolised in the organism and futureexperiments should be focused on determining the potentialeffects of the metabolites [27]

Currently treated water from the Songhua River is fornonpotable uses and MPSW is the exclusive waterworks runfor the water supply of Harbin city However populationgrowth and drought cycle are limited by the availability of rawwater from theMopanshan Reservoir Tomeet the increasingdemand local and regional water authorities have begun acampaign of second water supply project from the SonghuaRiver again which needs the protection of the Songhua Riverand advanced water treatment for the source

4 Conclusions

This study provided the first detailed data on the contami-nation status of 15 PAEs in the water near the MopanshanReservoir The concentration range of 15 PAEs in the sampleswas from 3558 to 92265 ngL with the mean value of29431 ngL DEHP andDBPwere themain pollutants among15 PAEs accounting for the main watershed pollution Theoccurrence and distribution of PAEs from different samplingsites in the water source varied largely suggesting that thespatial distribution of PAEs was site specific In additionthe monitoring of PAEs in the waterworks also showed thatPAEs can be detected in the drinking water and certaintoxicological risks to drinking water consumers were foundThese results reported here contribute to an understandingof how PAE contaminants are distributed in the new watersource and the waterworks in Harbin city as well as forminga basis for further modeling risk assessment and selection ofdrinking water treatment technology

In conclusion the results implied that no urgent reme-diation measures were required with respect to PAEs in thewaters However the ecological and health effects of thesesubstances through drinkingwater at the relatively lower con-centrations still need further notice in light of their possiblebiological magnifications Therefore the long-term sourcecontrol in the water and adding advanced treatment processfor drinking water supplies should be given special attentionin this area

Acknowledgments

This work was supported by the National Natural ScienceFoundation of China (1077029) the Funds for CreativeResearch Groups of China (Grant no 51121062) the NationalNatural Science Foundation of China (51078105) and theOpen Project of the State Key Laboratory of Urban WaterResource and Environment Harbin Institute of Technology(no QA201019)

References

[1] M Nikonorow H Mazur and H Piekacz ldquoEffect of orallyadministered plasticizers and polyvinyl chloride stabilizers inthe ratrdquo Toxicology and Applied Pharmacology vol 26 no 2 pp253ndash259 1973

[2] M Vitali M Guidotti G Macilenti and C Cremisini ldquoPhtha-late esters in freshwaters asmarkers of contamination sourcesmdasha site study in ItalyrdquoEnvironment International vol 23 no 3 pp337ndash347 1997

[3] G Latini C de Felice G Presta et al ldquoIn utero exposure todi-(2-ethylhexyl)phthalate and duration of human pregnancyrdquoEnvironmental Health Perspectives vol 111 no 14 pp 1783ndash17852003

[4] C E Mackintosh J A Maldonado M G Ikonomou and F AP C Gobas ldquoSorption of phthalate esters and PCBs in a marineecosystemrdquo Environmental Science and Technology vol 40 no11 pp 3481ndash3488 2006

[5] M Clara G Windhofer W Hartl et al ldquoOccurrence of phtha-lates in surface runoff untreated and treated wastewater andfate during wastewater treatmentrdquo Chemosphere vol 78 no 9pp 1078ndash1084 2010

[6] M M Abdel Daiem J Rivera-Utrilla R Ocampo-Perez J DMendez-Dıaz andM Sanchez-Polo ldquoEnvironmental impact ofphthalic acid esters and their removal fromwater and sedimentsby different technologiesmdasha reviewrdquo Journal of EnvironmentalManagement vol 109 pp 164ndash178 2012

[7] L Chen Y Zhao L Li B Chen and Y Zhang ldquoExposureassessment of phthalates in non-occupational populations inChinardquo Science of the Total Environment vol 427-428 pp 60ndash69 2012

[8] M J Teil M Blanchard andM Chevreuil ldquoAtmospheric fate ofphthalate esters in an urban area (Paris-France)rdquo Science of theTotal Environment vol 354 no 2-3 pp 212ndash223 2006

[9] P Roslev K Vorkamp J Aarup K Frederiksen and P HNielsen ldquoDegradation of phthalate esters in an activated sludgewastewater treatment plantrdquo Water Research vol 41 no 5 pp969ndash976 2007

[10] J Gasperi S Garnaud V Rocher and R Moilleron ldquoPrioritypollutants in wastewater and combined sewer overflowrdquo Scienceof the Total Environment vol 407 no 1 pp 263ndash272 2008

[11] F Zeng K Cui Z Xie et al ldquoOccurrence of phthalate estersin water and sediment of urban lakes in a subtropical cityGuangzhou South Chinardquo Environment International vol 34no 3 pp 372ndash380 2008

[12] F Zeng K Cui Z Xie et al ldquoPhthalate esters (PAEs) emergingorganic contaminants in agricultural soils in peri-urban areasaround Guangzhou Chinardquo Environmental Pollution vol 156no 2 pp 425ndash434 2008

[13] G Wildbrett ldquoDiffusion of phthalic acid esters from PVC milktubingrdquo Environmental Health Perspectives vol 3 pp 29ndash351973

8 Journal of Analytical Methods in Chemistry

[14] H Fromme T Kuchler T Otto K Pilz J Muller and AWenzel ldquoOccurrence of phthalates and bisphenol A and F inthe environmentrdquoWater Research vol 36 no 6 pp 1429ndash14382002

[15] A D Vethaak J Lahr S M Schrap et al ldquoAn integrated assess-ment of estrogenic contamination and biological effects in theaquatic environment ofTheNetherlandsrdquoChemosphere vol 59no 4 pp 511ndash524 2005

[16] C Dargnat M Blanchard M Chevreuil andM J Teil ldquoOccur-rence of phthalate esters in the Seine River estuary (France)rdquoHydrological Processes vol 23 no 8 pp 1192ndash1201 2009

[17] T Suzuki K Yaguchi S Suzuki and T Suga ldquoMonitoring ofphthalic acid monoesters in river water by solid-phase extrac-tion and GC-MS determinationrdquo Environmental Science andTechnology vol 35 no 18 pp 3757ndash3763 2001

[18] S Y Yuan C Liu C S Liao and B V Chang ldquoOccurrenceand microbial degradation of phthalate esters in Taiwan riversedimentsrdquo Chemosphere vol 49 no 10 pp 1295ndash1299 2002

[19] B Li C Qu and J Bi ldquoIdentification of trace organic pollutantsin drinking water and the associated human health risks inJiangsu Province Chinardquo Bulletin of Environmental Contami-nation and Toxicology pp 1ndash5 2012

[20] F Wang X Xia and Y Sha ldquoDistribution of phthalic acidesters in Wuhan section of the Yangtze River Chinardquo Journalof Hazardous Materials vol 154 no 1ndash3 pp 317ndash324 2008

[21] Y J Sha X H Xia and X Q Xiao ldquoDistribution characters ofphthalic acid ester in the waters middle and lower reaches ofthe Yellow Riverrdquo China Environmental Science vol 26 no 1pp 120ndash124 2006

[22] J Lu L-B Hao C-Z Wang W Li R-J Bai and D YanldquoDistribution characteristics of phthalic acid esters in middleand lower reaches of no 2 Songhua Riverrdquo EnvironmentalScience amp Technology vol 12 article 014 2007

[23] X J Zhu and Y Y Qiu ldquoMeasuring the phthalates of xiangjiangriver using liquid-liquid extraction gas chromatographyrdquoAdvanced Materials Research vol 301 pp 752ndash755 2011

[24] B L Yuan X Z Li and N Graham ldquoAqueous oxida-tion of dimethyl phthalate in a Fe(VI)-TiO

2

-UV reaction sys-temrdquoWater Research vol 42 no 6-7 pp 1413ndash1420 2008

[25] Z Yunrui ZWanpeng L FudongW Jianbing and Y ShaoxialdquoCatalytic activity of RuAl2O3 for ozonation of dimethylphthalate in aqueous solutionrdquo Chemosphere vol 66 no 1 pp145ndash150 2007

[26] H N Gavala U Yenal and B K Ahring ldquoThermal andenzymatic pretreatment of sludge containing phthalate estersprior tomesophilic anaerobic digestionrdquoBiotechnology and Bio-engineering vol 85 no 5 pp 561ndash567 2004

[27] Y Guo Q Wu and K Kannan ldquoPhthalate metabolites in urinefrom China and implications for human exposuresrdquo Environ-ment International vol 37 no 5 pp 893ndash898 2011

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 210653 8 pageshttpdxdoiorg1011552013210653

Research ArticleSimultaneous Determination of Hormonal Residuesin Treated Waters Using Ultrahigh Performance LiquidChromatography-Tandem Mass Spectrometry

Rayco Guedes-Alonso Zoraida Sosa-Ferrera and Joseacute Juan Santana-Rodriacuteguez

Departamento de Quımica Universidad de Las Palmas de Gran Canaria 35017 Las Palmas de Gran Canaria Spain

Correspondence should be addressed to Jose Juan Santana-Rodrıguez jsantanadquiulpgces

Received 28 December 2012 Accepted 7 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Rayco Guedes-Alonso et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

In the last years hormone consumption has increased exponentially Because of that hormone compounds are considered emergingpollutants since several studies have determinted their presence in water influents and effluents of wastewater treatment plants(WWTPs) In this study a quantitative method for the simultaneous determination of oestrogens (estrone 17120573-estradiol estriol17120572-ethinylestradiol and diethylstilbestrol) androgens (testosterone) and progestogens (norgestrel andmegestrol acetate) has beendeveloped to determine these compounds in wastewater samples Due to the very low concentrations of target compounds in theenvironment a solid phase extraction procedure has been optimized and developed to extract and preconcentrate the analytesDetermination and quantification were performed by ultrahigh performance liquid chromatography-tandem mass spectrometry(UHPLC-MSMS) The method developed presents satisfactory limits of detection (between 015 and 935 ngsdotLminus1) good recoveries(between 73 and 90 for the most of compounds) and low relative standard deviations (under 84) Samples from influents andeffluents of two wastewater treatment plants of Gran Canaria (Spain) were analyzed using the proposed method finding severalhormones with concentrations ranged from 5 to 300 ngsdotLminus1

1 Introduction

In general it is supposed that more than 100000 differentchemical compounds can be introduced in the Environmentmany of them in very small quantity However a lot of thesecompounds are not included as pollutants in the legislationAlthough these compounds named emerging pollutants arenot regulated as pollutants they probably will be in the futurebecause of their potential negative effect in the ecosystem For20 years many articles have reported the presence of theseldquonew compoundsrdquo in wastewater [1 2]

The emerging pollutant origin is mainly anthropogenicconsidering that the majority of these compounds are bio-logically active substances that are synthesized to use themin agriculture industry and medicine The main source ofthese emerging pollutants is the residual urbanwaters and thewastewater treatment plants effluents because many of these

WWTPs are not designed or optimized to treat this kind ofcompounds [3]

Hormones are one of the most potent endocrine disrupt-ing compounds as well as are considered also as emergingpollutants Hormones can be differentiated in oestrogensandrogens and progestogens Some of them have limits intheir use but not a specific legislation [4]

The main characteristic of these pollutants is that it isnot necessary to remain in the environment to cause negativeeffects in view of the fact that their constant introduction init offsets their removal or degradation [5]

The steroid hormones help controlling the metabolisminflammations immunological functions water and salt bal-ance sexual development and the capacity of withstandingillnesses [6] The term steroid can be used for naturalhormones produced by the body as well as for artificiallyproduced medicines that increase the natural steroid effect

2 Journal of Analytical Methods in Chemistry

In the last 50 years the natural and synthetic hormoneworldwide consumption has grown as much as in humanmedicine as in cattle farming and they become the mostprescribed medicines [7]

A significant quantity of consumed oestrogens leaves theorganism through excretions For example 17120573-estradiol (E2)is oxidized rapidly becoming an estrone (E1) that can turninto estriol afterwards (E3) Besides the 17120572-ethinyl estradiol(EE) is excreted as conjugated [8]

With regard to emission sources in the first place arethe wastewater treatment plants (WWTPs) [9] and secon-darily cattle waste such as those leachates from dung anduncontrolled dumping [10] Several studies made in theWWTPs have reported that the treatment plants are capableof eliminating around 60 of hormones [11ndash13]

The identification of hormone residues in environmentis of special interest because knowledge of these compoundsis a requirement to take measures in order to regulate andminimize their environmental impact

However measurement of hormone residues is a verydifficult task not only due to the difficulty in measuringvery low concentration but also due to a very complexityof the samples Therefore use of mass spectrometer (MS)as detector coupled with chromatography techniques hasbecome a powerful method for the analysis of these typesof compounds at trace levels [14ndash17] Consequently LC-MSMS is the principally chosen technique One of the mainadvantages of LC-MSMS is its ability to analyze hormoneswithout derivatization (necessary in GC) or the need ofhydrolyze the conjugated form

Due to low level concentration of these compounds inenvironmental water it is necessary to apply an extractionand preconcentration method prior to LC analysis The mostused technique of extraction and preconcentration methodfor liquid samples is the solid phase extraction (SPE) [18ndash20]

The objective of this study is to develop a rapid and simpleprocedure of extraction preconcentration and determina-tion of four steroid oestrogens (estrone (E1) 17120573-estradiol(E2) estriol (E3) and 17120572-ethinylestradiol (EE)) one non-steroidal oestrogen the diethylstilbestrol (DES) one andro-gen the testosterone (TES) and two synthetic progestogensnorgestrel (NOR) and megestrol acetate (MGA) (Table 1)based on solid phase extraction and ultrahigh performanceliquid chromatography-tandem mass spectrometry (SPE-UHPLC-MSMS) The developed method was applied tothe identification and quantification of these compoundsin wastewater samples obtained from the influents andeffluents of two wastewater treatment plants (WWTPs) ofGran Canaria (Spain) They presented different methodsof wastewater treatments WWTP 1 presented a traditionalmethod based on activated sludge while WWTP 2 used amembrane bioreactor technique

2 Materials and Methods

21 Reagents All of the hormonal compounds usedwere pur-chased from Sigma-Aldrich (Madrid Spain) Stock solutionscontaining 1000mgsdotLminus1 of each analyte were prepared by

dissolving the compound inmethanol and the solutionswerestored in glass-stoppered bottles at 4∘C prior to use Workingaqueous standard solutions were prepared daily Ultrapurewater was provided by a Milli-Q system (Millipore BedfordMA USA) HPLC-grade methanol LC-MS methanol andLC-MS water as well as the ammonia and the ammoniumacetate used to adjust the pH of the mobile phases wereobtained from Panreac Quımica (Barcelona Spain)

22 Sample Collection Water samples were collected fromthe effluents of twowastewater treatment plants located in thenorthern area of Gran Canaria in May and August of 2012WWTP 1 used a conventional activated sludge treatmentsystem while WWTP 2 employed a membrane bioreactortreatment system The samples were collected in 2 L amberglass bottles that were rinsed beforehand with methanol andultrapurewater Samples were purified through filtrationwithfibreglass filters and then with 065 120583m membrane filters(Millipore Ireland) The samples were stored in the dark at4∘C and extracted within 48 hours

23 Instrumentation For the SPE optimization the instru-ment used was an ultrahigh performance liquid chromatog-raphy with fluorescence detector (UHPLC-FD) system con-sisting of an ACQUITYQuaternary Solvent Manager (QSM)used to load samples and wash and recondition the analyticalcolumn an autosampler a column manager and a fluores-cence detector with excitation and emission wavelengths of280 and 310 nm respectively all fromWaters (Madrid Spain)

The analysis of wastewater samples was performed ina UHPLC-MSMS system from Waters (Madrid Spain)similar to the described above with a 2777 autosamplerequipped with a 25120583L syringe and a tray to hold 2mLvials and an ACQUITY tandem triple quadrupole (TQD)mass spectrometer with an electrospray ionization (ESI)interface All Waters components (Madrid Spain) werecontrolled using the MassLynx Mass Spectrometry SoftwareElectrospray ionisation parameters were fixed as followsthe capillary voltage was 3 kV in positive mode and minus2 kVin negative mode the source temperature was 150∘C thedesolvation temperature was 500∘C and the desolvation gasflow rate was 1000 Lhr Nitrogen was used as the desolvationgas and argon was employed as the collision gas

The detailed MSMS detection parameters for each hor-monal compound are presented in Table 2 and were opti-mised by the direct injection of a 1mgsdotLminus1 standard solutionof each analyte into the detector at a flow rate of 10 120583Lsdotminminus1

24 Chromatographic Conditions For the SPE optimizationthe analytical column was a 50mm times 21mm ACQUITYUHPLCBEHWaters C

18columnwith a particle size of 17120583m

(Waters Chromatography Barcelona Spain) operating at atemperature of 30∘C Analytes separation was carried outemploying the following gradient starting at 55 45 (vv)water methanol for 1 minute During 3 minutes it changedto 50 50 (vv) and stayed for 25 minutes more Finally cameback to initial conditions in 1 minute and stayed for 15

Journal of Analytical Methods in Chemistry 3

Table 1 List of hormonal compounds pKa values chemical structure and retention times

Compound pKa [21] Structure 119905119877

(min)

E3 Estriol 103

HO

OH

OH

H H

H096

E2 17120573-estradiol 103

HO

OH

H H

H218

EE 17120572-ethinylestradiol 103

HO

HO

H H

H223

E1 Estrone 103

HO

O

H

H H220

DES Diethylstilbestrol 102

HO

OH

235

TES Testosterone 151

OH

OH H

H240

MGA Megestrol acetate

O

O

O

OH

H

H306

NOR Levonorgestrel 131

OH

O

H

H

H

H263

minutes Therefore the analysis took 9 minutes at a flow of05mLsdotminminus1

For the analysis of real samples aUHPLC-MSMS systemwas used The analytical column was the same and themobile phase was water and methanol adjusted with a bufferconsisting in 01 vv ammonia and 15mM of ammoniumacetate The analysis was performed in gradient mode at aflow rate of 03mLsdotminminus1The gradient started at 50 50 (vv)mixture of water methanol which changed to 25 75 (vv) in3 minutes and returned to 50 50 in 1 minute more Finallythe gradient stayed calibrating for another 15 minutes moreThe sample volume injected was 5120583L

3 Results and Discussion

31 Optimization of Solid-Phase Extraction (SPE) There area number of parameters that affect SPE procedure such as

type of sorbent pH ionic strength sample and desorptionvolumes and wash step To optimize these parameters itused Milli-Q water spiked with a solution of fluorescenceoestrogens (estriol 17120573-estradiol and 17120572-ethinylestradiol)to obtain a final concentration of 250120583gsdotLminus1

The first parameter to optimize is the choice of sorbentsince it controls the selectivity affinity and capacity overanalytes In this study the SPE cartridges used were OASISHLB SepPak C

18(both from Waters Madrid Spain) and

BondElut ENV (fromAgilent Madrid Spain) Keeping otherparameters fixed (ionic strength of 0 sample volume of100mL) the cartridges were studied at three different pHs(5 8 and 11) From the results obtained it can be observedthat the better signals are found for SepPak C

18cartridge

(Figure 1)After choosing the optimum cartridge we used an initial

experimental design of 23 to study the influence of pH ionic

4 Journal of Analytical Methods in Chemistry

Table 2 Mass spectrometer parameters for the determination of target analytes

Compound Precursor ion(mz)

Capillary voltage(Ion mode)

Quantification ionmz(collision potential V)

Quantification ionmz(collision potential V)

E3 2872 minus65V (ESI minus) 1710 (37) 1452 (39)E2 2712 minus65V (ESI minus) 1451 (40) 1831 (31)EE 2952 minus60V (ESI minus) 1450 (37) 1589 (33)E1 2692 minus65V (ESI minus) 1450 (36) 1430 (48)DES 2671 minus50V (ESI minus) 2371 (29) 2511 (25)TES 2892 38V (ESI +) 1870 (18) 1040 (21)MGA 3855 30V (ESI +) 2673 (15) 2242 (30)NOR 3132 38V (ESI +) 1090 (26) 2451 (18)

0

500

1000

1500

2000

2500

E3 E2 EE

Peak

area

Cartridge optimizationOASIS HLB pH = 5

OASIS HLB pH = 8

OASIS HLB pH = 11SepPak C18 pH = 5

SepPak C18 pH = 8

SepPak C18 pH = 11BondElut ENV pH = 5

BondElut ENV pH = 8

BondElut ENV pH =11

Figure 1 Optimization of SPE cartridges

strength and sample volume over extraction process Theexperimental design was obtained using Statgraphics Plussoftware 51 and the statistics study was done with IBM SPSSStatistics 19 We assessed two levels and three parameters pH(3 and 8) ionic strength (0 and 30 of NaCl) and samplevolume (50 and 250mL) to obtain the influence of eachparameter and the variable correlation to each other In thisstudy it is observed that the ionic strength and sample volumehad the major influence on the recoveries of the analytesFor that a 32 factorial design to optimize these two variablesat three levels per parameter (0 15 and 30 of NaCl forionic strength and 50 100 y 250mL for sample volume) wasused Figure 2 shows the response surface obtained for theestriol and 17120572-ethinylestradiol The results obtained showedthat an increment of the ionic strength did not producean increase in the response area of the compound and theoptimum volume was 250mL Because of that a solutionwithout salt addition and 250mL of sample volume waschosen Finally the desorption volume (1mLofmethanol and2mL of methanol in one and two steps) and wash-step (5mL

ofMilli-Q water and 5mL ofMilli-Q water with 5 and 10 ofmethanol vv) were assayed to complete the optimization ofthe SPE process The optimum values were 2mL of methanolin one step and 5mL of Milli-Q water without methanolrespectively

In accordance with the obtained results the optimumconditions for SPE procedure were SepPak C

18cartridge

250mL of sample at pH = 8 and 0 of NaCl desorptionwith 2mL of methanol in one step and wash step with5mL of Milli-Q water In these conditions we achieved apreconcentration factor of 125 In Figure 3 a chromatogramwith the optimum conditions is shown where the peaksof all compounds in their corresponding transitions can beobserved

32 Analytical Parameters Because of the SPE optimizationthat was done only with fluorescent compounds (estriol 17120573-estradiol and 17120572-ethinylestradiol) it was necessary to studythe recoveries of all the hormonal compounds using theoptimized SPE-UHPLC-MSMSmethod All the compoundsunder study showed good recoveries over 73 except thediethylstilbestrol with a recovery of 507

A calibration curve was used for the quantification ofthe analytes by diluting the stock solution of each analyteinto the samples to concentrations ranging between 1 and100 120583gsdotLminus1 Analysis was conducted by UHPLC-MSMS andlinear calibration plots for each analyte (1199032 gt 099) wereobtained based on their chromatographic peak areas

The limit of detection (LOD) and the limit of quantifi-cation (LOQ) for each compound were calculated from thesignal-to-noise ratio of each individual peak The LOD wasdefined as the lowest concentration that gave a signal-to-noiseratio that was greater than 3 The LOQ was defined as thelowest concentration that gave a signal to noise ratio that wasgreater than 10The LODs ranged from015 to 935 ngsdotLminus1 andthe LOQs ranged from 049 to 3118 ngsdotLminus1

The performance and reliability of the process werestudied by determining the repeatability of the quantificationresults for all target analytes under the described conditionsusing six samples (119899 = 6) The relative standard deviations(RSDs) were lower than 84 in all cases indicating a

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 7: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 256956 1 pagehttpdxdoiorg1011552013256956

EditorialAnalysis and Fate of Emerging Pollutants duringWater Treatment

Fei Qi1 Guang-Guo Ying2 Kaimin Shih3 Jolanta Kumirska4

Elif Pehlivanoglu-Mantas5 and Xiaojun Luo2

1 Beijing Key Lab for Source Control Technology of Water Pollution College of Environmental Science and EngineeringBeijing Forestry University No 35 Qinghua East Road Beijing 100083 China

2 State Key Laboratory of Organic Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of SciencesGuangzhou 510640 China

3Department of Civil Engineering The University of Hong Kong Pokfulam Road Hong Kong4Department of Environmental Analysis Faculty of Chemistry University of Gdansk Sobieskiego 1819 80-952 Gdansk Poland5 Environmental Engineering Department Istanbul Technical University Ayazaga Campus Maslak 34469 Istanbul Turkey

Correspondence should be addressed to Fei Qi qifeibjfueducn

Received 23 April 2013 Accepted 23 April 2013

Copyright copy 2013 Fei Qi et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Emerging pollutants defined as compounds that are notcurrently covered by existing water-quality regulations allover the world have not been studied widely before and arethought to be potential threats to environmental ecosystemsand human health This special issue compiles 5 excitingpapers which are very meticulously performed researches

Generally emerging pollutants encompass a diversegroup of compounds including pharmaceuticals drugs ofabuse personal-care products (PCPs) steroids and hor-mones surfactants perfluorinated compounds (PFCs) flameretardants industrial additives and agents gasoline additivesnew disinfection byproducts (DBPs) nanomaterials and thetoxic minerals

The analysis methods occurrence and fate of hormonaland endocrine disruptors compounds (EDCs) were dis-cussed in two papers of this special issue R Guedes-Alonsoet al determine the hormonal residues in treated water byultrahigh performance liquid chromatography-tandem massspectrometry (UPLC-MS) and evaluate the efficiency ofthe conventional wastewater treatment for the removal ofhormonal compounds Moreover Y Liu et al study anotherkinds of PPCPs named as phthalate esters that is typicalkind of EDCs The occurrence in a surface water and theremoval efficiency in a traditional drinking water treatmentpalnt are studied According to results of the two papers

the occurrence and fate of hormonal and EDCs in water orwastewater treatment are very clear

J Xing et al report a new wastewater treatment technol-ogy bioflocculation for the removal of sulfamethoxazole thatis a typical pharmaceutical in wastewater The performanceand the reaction mechanism of the biodegradation of sul-famethoxazole by the bioflocculation are discussed in depthMoreover the optimum reaction condition is obtained

The heavy metal and toxic mineral are also importantpollutants in the environment especially in the mining areaTwo papers of this issue are focused on this K Naeemul-lah et al report a green preconcentration method for thedetermination of cobalt and lead in water Y Liu et al do anovel research on the electrochemical reaction of pyrite as asimulation of the natural environmental

By compiling this special issue we hope to enrich ourreaders and researchers on the analysis and fate of emergingpollutants during water treatment

Fei QiGuang-Guo Ying

Kaimin ShihJolanta Kumirska

Elif Pehlivanoglu-MantasXiaojun Luo

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 419349 8 pageshttpdxdoiorg1011552013419349

Research ArticleOccurrence and Removal Characteristics of Phthalate Estersfrom Typical Water Sources in Northeast China

Yu Liu Zhonglin Chen and Jimin Shen

State Key Laboratory of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Jimin Shen shenjiminhiteducn

Received 21 December 2012 Accepted 3 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Yu Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The presence of phthalate esters (PAEs) in the environment has gained a considerable attention due to their potential impactson public health This study reports the first data on the occurrence of 15 PAEs in the water near the Mopanshan Reservoirmdashthenew and important water source of Harbin city in Northeast China As drinking water is a major source for human exposureto PAEs the fate of target PAEs in the two waterworks (Mopanshan Waterworks and Seven Waterworks) was also analyzed Theresults demonstrated that the total concentrations of 15 PAEs in the water near the Mopanshan Reservoir were relatively moderateranging from 3558 to 92265 ngL with the mean value of 29431 ngL DBP and DEHP dominated the PAE concentrations whichranged from 525 to 44982 ngL and 1289 to 65709 ngL respectivelyThe occurrence and concentrations of these compoundswereheavily spatially dependent Meanwhile the results on the waterworks samples suggested no significant differences in PAE levelswith the input of the raw waters Without effective and stable removal of PAEs after the conventional drinking water treatment inthe waterworks (258 to 765) the risks posed by PAEs through drinking water ingestion were still existing which should bepaid special attention to the source control in theMopanshan Reservoir and some advanced treatment processes for drinking watersupplies

1 Introduction

Phthalate acid esters a class of chemical compounds mainlyused as plasticizers for polyvinyl chloride (PVC) or to alesser extent other resins in different industrial activities areubiquitous in the environment and have evoked interest inthe past decade due to endocrine disrupting effects and theirpotential impacts on public health [1ndash3]

Worldwide production of PAEs is approximately 6 mil-lion tons per year [4] As PAEs are not chemically boundto the polymeric matrix in soft plastics they can enter theenvironment by losses during manufacturing processes andby leaching or evaporating from final products [5]Thereforethe occurrence and fate of specific PAEs in natural waterenvironments have been observed and also there are a lot ofconsiderable controversies with respect to the safety of PAEsin water [5ndash10]

Six PAE compounds including dimethyl (DMP) diethyl(DEP) dibutyl (DBP) butylbenzyl (BBP) di(2-ethylhexyl)

(DEHP) and di-n-octyl phthalate (DNOP) are classifiedas priority pollutants by the US Environmental ProtectionAgency (EPA) Though the toxicity of PAEs to humans hasnot been well documented for some years the Ministry ofEnvironmental Protection in China has regulated phthalatesas environmental pollutants In addition the standard inChina concerning analytical controls on drinkingwaters doesnot specifically identify any PAEs as organic pollutant indexesto be determined by the new drinking water standard in 2007(Standard for drinking water quality GB5749-2006) whichwas forced to be monitored for the drinking water supplies in2012 Consequently official data about the presence of thesepollutants in the aquatic environment of some cities are notavailable

Harbin the capital of Heilongjiang Province is a typicallyold industrial base and economically developed city with apopulation of over 3million inNortheast China As the newlyenabledwater source forHarbin cityMopanshanwaterworkssupply the whole city with drinking water through long

2 Journal of Analytical Methods in Chemistry

China

HarbinMopanshan

Reservoir

LongfengshanReservoir

Figure 1 Spatial distribution of the 16 sampling sites near the Mopanshan Reservoir in Northeast China

distance transfer from the Mopanshan Reservoir To theauthorsrsquo knowledge the occurrence and fate of PAEs in thewater near this area and its relative waterworks have notpreviously been examined

The objectives of this study were (i) to determine theoccurrence of PAEs and clarify the fate and distribution ofthe pollutants in the water source (ii) to examine the twowaterworks where traditional drinking water treatment stepwas evaluated on the PAEs removal efficiencies and (iii) toevaluate the potential for adverse effects of PAEs on humanhealth Therefore the investigation of PAEs in the water canprovide a valuable record of contamination in Harbin city

2 Materials and Methods

21 Chemical Fifteen PAEs standard mixture includingdimethyl phthalate diethyl phthalate diisobutyl phthalatedi-n-butyl phthalate di(4-methyl-2-pentyl) phthalate di(2-ethoxyethyl) phthalate di-n-amyl phthalate di-n-hexylphthalate butyl benzyl phthalate di(hexyl-2-ethylhexyl)phthalate di(2-n-butoxyethyl) phthalate dicyclohexyl phthal-ate di(2-ethylhexyl) phthalate di-n-nonyl phthalate di-n-octylphthalate at 1000 120583gmL each and surrogate standardsconsisting of diisophenyl phthalate di-n-phenyl phthal-ate and di-n-benzyl phthalate in a mixture solution of500120583gmL each were supplied by AccuStandard Inc Asthe internal standard benzyl benzoate was also purchasedfrom AccuStandard Inc All solvents (acetone hexane anddichloromethane) used were HPLC-grade and were pur-chased from J T Baker Co (USA) Anhydrous sodiumsulfate (Tianjin Chengguang Chemical Reagent Co China)was cleaned at 600∘C for 6 h and then kept in a desiccatorbefore use

22 Sample Collection and Preparation Harbin the capitalof Heilongjiang province in China imports nearly all of itsdrinking water from two sources the Mopanshan Reservoir

Raw water Coagulation sedimentation Filtration Tank

Sampling site Sampling site

Figure 2 Schematic diagram of the waterworks

(long-distance transport project) and the Songhua River (oldwater source)

Water samples from the Mopanshan Reservoir andMopanshan waterwork were collected in 2008 The locationsof the sampling sites near the Mopanshan Reservoir are pre-sented in Figure 1 as a comparison sampling from anotherHarbin water supplymdashSeven waterworks with water sourcefrom the SonghuaRiverwas performed in 2011 In eachwater-works with considering the hydraulic retention time threesets of raw water samples (influent) were taken and thenthe final finished waters (effluent) after the whole treatmentprocess were carried out for the collectionsThe flow diagramof the waterworks is shown in Figure 2

Samples were collected using 20 L glass jars from 05mbelow the water surface During the whole sampling processthe global position system was used to locate the samplingstations (details in Table 1) All samples were transferred tothe laboratory directly after sampling and stored at 4∘C priorto extraction within 2 d

Water samples were filtered under vacuum through glassfiber filters (07 120583mpore sizes) Prior to extraction each sam-ple was spiked with surrogate standards The water sampleswere extracted based on a classical liquid phase extractionmethod (USEPA method 8061) with slight modificationsBriefly 1 L of water samples was placed in a separating funneland extracted by means of mechanical shaking with 150mLdichloromethane and then with filtration on sodium sulfate(about 20 g) the organic extracts were concentrated usinga rotary evaporator The exchange of solvent was done byreplacing dichloromethane with hexane Finally they were

Journal of Analytical Methods in Chemistry 3

Table 1 Detailed descriptions of the sampling locations

Number Sampling site Name Latitude Longitude1 Lalin Jinsan Bridge Mangniu River E127∘0210158405310158401015840 N45∘510158404510158401015840

2 Xingsheng Town Gaojiatun Lalin River E127∘0610158401110158401015840 N44∘5110158405710158401015840

3 Dujia Town Shuguang Lalin River E127∘1010158404410158401015840 N44∘4810158404110158401015840

4 Shanhe Town Taipingchuan Lalin River E127∘1810158403610158401015840 N44∘4310158405010158401015840

5 Xiaoyang Town Qichuankou Lalin River E127∘2310158405410158401015840 N44∘3910158404610158401015840

6 Shahezi Town Mopanshan Reservoir E127∘3810158405910158401015840 N44∘2410158401710158401015840

7 Shahezi Town Gali Lalin River E127∘3510158401710158401015840 N44∘3110158405610158401015840

8 Chonghe Town Changcuizi Mangniu River E127∘4610158403610158401015840 N44∘3510158404610158401015840

9 Chonghe Town Xingguo Mangniu River E127∘3510158401710158401015840 N44∘3110158405710158401015840

10 Longfeng Town Mangniu River E127∘3510158401910158401015840 N44∘4310158404810158401015840

11 Changpu Town Zhonghua Mangniu River E127∘1610158403010158401015840 N45∘110158404210158401015840

12 Erhe Town Shuanghe Mangniu River E127∘1810158403210158401015840 N45∘410158402810158401015840

13 Zhiguang Town Songjiajie Mangniu River E127∘341015840310158401015840 N45∘110158402010158401015840

14 Zhiguang Town Wuxing Mangniu River E127∘2910158402010158401015840 N45∘010158404310158401015840

15 Changpu Town Xingzhuang Mangniu River E127∘1010158404210158401015840 N45∘410158403610158401015840

16 Yingchang Town Xingguang Lalin River E126∘551015840810158401015840 N45∘91015840010158401015840

reduced to 05mL under gentle nitrogen flow The internalstandard was added to the sample prior to instrumentalanalysis

23 Chemical Analysis The extracted compounds weredetermined by gas chromatography coupled to mass spec-trometer analysis as described in other publications [1112] Briefly extracted samples were injected into an Agilent6890 Series GC equipped with a DB-35MS capillary column(Agilent 30m times 025mm id 025120583m film thickness) andan Agilent 5973 MS detector operating in the selective ionmonitoring mode The column temperature was initially setat 70∘C for 1min then ramped at 10∘Cmin to 300∘C andheld constant for 10min The transfer line and the ion sourcetemperature were maintained at 280 and 250∘C respectivelyHelium was used as the carrier gas at a flow rate of 1mLminThe extracts (20 120583L) were injected in splitless mode with aninlet temperature of 300∘C

24 Quality Assurance and Quality Control All glasswarewas properly cleaned with acetone and dichloromethanebefore use Laboratory reagent and instrumental blanks wereanalyzed with each batch of samples to check for possiblecontamination and interferences Only small levels of PAEswere found in procedural blanks in some batches andthe background subtraction was appropriately performed inthe quantification of concentration in the water samplesCalibration curves were obtained from at least 3 replicateanalyses of each standard solution The surrogate standardswere added to all the samples to monitor matrix effectsRecoveries of PAEs ranged from 62 to 112 in the spikedwater and the surrogate recoveries were 751 plusmn 127 fordiisophenyl phthalate 723 plusmn 143 for di-n-phenyl phtha-late and 1026 plusmn 104 for di-n-benzyl phthalate in thewater samples The determination limits ranged from 6 to30 ngL A midpoint calibration check standard was injected

as a check for instrumental drift in sensitivity after every10 samples and a pure solvent (methanol) was injected as acheck for carryover of PAEs from sample to sample All theconcentrations were not corrected for the recoveries of thesurrogate standards

3 Results and Discussion

31 PAEs in Water Source The PAEs in the waters fromthe sampling sites near the Mopanshan Reservoir wereinvestigated and the results are presented in Table 2 Thesum15

PAEs concentrations ranged from 3558 to 92265 ngLwith the geometric mean value of 29431 ngL Among the15 PAEs detected in the waters DIBP DBP and DEHP weremeasured in all the samples with the average concentrationsbeing 1966 8014 and 17741 ngL respectively The threePAE congeners are important and popular addictives inmany industrial products including flexible PVC materialsand household products suggesting the main source of PAEcontaminants in the water [13] The correlations of the con-centration of DEHP DBP and DIBP with the concentrationsof total PAEs in the water samples are shown in Figure 3and a relatively significant correlation between sum

15

PAEs andDEHP concentration was found suggesting the importantpart played by DEHP in total concentrations of PAEs inthe water bodies near the Mopanshan Reservoir In otherwords the contribution of DEHP to total PAEs was higherthan that of other PAE congeners in the water samples Inaddition DMP DEP and DNOP with the mean value of140 284 and 541 ngL respectively only detected at somesampling sites and have also attracted much attention asthe priority pollutants by the China National EnvironmentalMonitoring Center On the contrary the concentrations of6 PAEs (DMEP BMPP BBP DBEP DCHP and DNP) werebelow detection limits in all the water samples near theMopanshan Reservoir which is easily explained in terms ofmuch lower quantities of present use in China

4 Journal of Analytical Methods in Chemistry

0 2000 4000 6000 80000

2000

4000

6000

Con

cent

ratio

ns (n

gL)

DEHP

119903 = 0885 119875 lt 001

sum15PAEs (ngL)

(a)

0 2000 4000 6000 80000

2000

4000

Con

cent

ratio

ns (n

gL)

sum15PAEs (ngL)

DBP

119903 = 0812 119875 lt 001

(b)

1000

500

0

0 2000 4000 6000 8000sum15PAEs (ngL)

DIBP

Con

cent

ratio

ns (n

gL)

119903 = 0724 119875 lt 001

(c)

Figure 3 Correlations of the concentration of the major PAEs (DEHP DBP and DIBP) with the concentrations of total PAEs in the watersamples

Table 2 Concentrations of 15 PAEs in water samples near the Mopanshan Reservoir

PAEs Abbreviation Water (ngL)Range Mean Frequency

Dimethyl phthalate DMP ndndash424 140 816Diethyl phthalate DEP ndndash550 284 1516Diisobutyl phthalate DIBP 400ndash6588 1966 1616Dibutyl phthalate DBP 525ndash44982 8014 1616bis(2-methoxyethyl)phthalate DMEP nd nd 016bis(4-methyl-2-pentyl)phthalate BMPP nd nd 016bis(2-ethoxyethyl)phthalate DEEP ndndash546 128 516Dipentyl phthalate DPP ndndash925 455 1016Dihexyl phthalate DHXP ndndash651 162 516Benzyl butyl phthalate BBP nd nd 016bis(2-n-butoxyethyl)phthalate DBEP nd nd 016Dicyclohexyl phthalate DCHP nd nd 016bis(2-ethylhexyl)phthalate DEHP 1289ndash65709 17741 1616Di-n-octyl phthalate DNOP ndndash4482 541 516Dinonyl phthalate DNP nd nd 016sum15

PAEs 3558ndash92265 29431 mdash

The distribution of 15 PAEs (sum15

PAEs) studied and6 US EPA priority PAEs (sum

6

PAEs including DMP DEPDIBP DBP DEHP and DNOP) in the waters from differentsampling sites are shown in Figure 4 There was an obviousvariation in the total sum

15

PAEs concentrations in water sam-ples near the Mopanshan Reservoir the concentrations ofsum6

PAEs from the same sampling sites varied from 2690 to90860 ngL with an average of 28686 ngL the distributionspectra of which observed for all the sampling sites weresimilar tosum

15

PAEsThe highest levels of PAEs contaminationwere seen on the sampling site 3 followed by some relativelyheavily polluted sites (site 16 13 9 10 and 11) indicating thatthese sites served as important PAE sources and the spatialdistribution of PAEs was site specific The levels in the watersexamined varied over a wide range especially in theMangniu

River near theMopanshan Reservoir (in some case overmorethan one order of magnitude) In general it should be notedthat there might be a relation of PAEs levels with the input oflocal waste such as sewage water food packaging and scrapmaterial near the sampling point which were found duringthe sampling period

32 PAE Congener Profiles in the Water Different PAE pat-terns may indicate different sources of PAEs Measurementof the individual PAE composition is helpful to track thecontaminant source and demonstrate the transport and fateof these compounds in water [11] The relative contributionsof the 9 detectable PAE congeners to thesum

15

PAEs concentra-tions in the water are presented in Figure 5 It is clear thatDEHP was the most abundant in the water samples with

Journal of Analytical Methods in Chemistry 5

0

500

1000

1500

4000

6000

8000

10000

Con

cent

ratio

ns (n

gL)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

sum15PAEssum6PAEs

Figure 4 Spatial distributions of the 16 sampling sites near theMopanshan Reservoir

the exception of site 2 3 and 11 contributions ranging from331 to 963 followed byDBP ranging from 21 to 363The results are consistent with the above data for overallanalysis that DBP and DEHP are the dominant componentsof the PAEs distribution pattern in each sampling site whichreflected the different pattern of plastic contaminant inputduring the sampling period Similarly DIBP and DBP areused in epoxy resins or special adhesive formulations withthe different proportions of these two PAE congeners whichwere also the important indicator of the information pollutedby PAEs for the sampling locations Although the limitedsample number draws only limited conclusions there is stillreason to note that a leaching from the plastic materials intothe runoff water is possible and that water runoff from thecontaminated water is a burden pathway from differentsources of PAEs [14]

33 Comparison with Other Water Bodies Comparison withthe total PAEs concentrations is nevertheless very limited dueto the different analysis compounds However the individualPAE namely DBP and DEHP is by far the most abundantin other researches and it is possible to make a camparisonwith our findings In this case the results of DBP and DEHPconcentrations published in literatures for kinds of waterbodies are presented together in Table 3

The DEHP and DBP concentrations of the present studyshowed to some extent lower concentration levels than thosereported in the other water bodies in China In comparisonthe results were comparable or similar to those from theexaminations described in other foreign countries For exam-ple as shown in Table 3 the DEHP concentrations were sim-ilar to the surface waters from the Netherlands and Italydescribed in the literature Meanwhile these concentrationsin this study were quite lower than the Yangtze River andSecond Songhua River in China

0

20

40

60

80

100

DEEP DPP DHXP DEHP DNOP DBP

DIBP DEP DMP

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

Com

posit

ion

()

Figure 5 PAE composition of thewater samples in 16 sampling sites

In conclusion as compared to the results of other studiesthe waters near the Mopanshan Reservoir were moderatelypolluted by PAEs Therefore there is a definite need to set upa properly planned and systematic approach to water controlnear the Mopanshan Reservoir

34 PAE Levels in the Waterworks The Mopanshan Water-works (MPSW) equipped essentially with the water sourceof the Mopanshan Reservoir has been investigated in orderto assess the fate of the PAEs during the drinking watertreatment process For comparison a sampling campaign forthe determination of PAEs levels in the Seven Waterworks(SW waterworks with the old water source of the SonghuaRiver) was carried out Both waterworks operate coagulationsedimentation and followed by filtration treatment processwhich are typical traditional drinking water treatment

The measured concentrations in the raw and finishedwater of the two investigated waterworks are shown inFigure 6 Six out of fifteen PAEs were detected in the fin-ished water from the two waterworks The detected PAEswere DMP DEP DIBP DBP DEHP and DNOP and theother investigated phthalates are of minor importance withconcentrations all below the limit of detection As showin Figure 6 the measured concentrations of the analyzedPAEs in the finished water of the two waterworks variedstronglyThemost important compound in the finishedwaterwas DEHP with the mean concentration of 34737 and40592 ngL for the MPSW and SW respectively suggestingthe highest relative composition of total PAE concentrationsin the drinking water

For the raw water from the different water sources DMPand DIBP concentrations in the MPSW were much lowerthan the ones in the SW and the concentrations of DEPDBP DEHP andDEHPwere relatively comparable in the two

6 Journal of Analytical Methods in Chemistry

Table 3 Comparison of the concentrations of DEHP and DBP in the water bodies (ngL)

Location DEHP DBP ReferenceRange Median Mean Range Median Mean

Surface water Germany 330ndash97800 2270 mdash 120ndash8800 500 mdash [14]Surface water the Netherlands ndndash5000 320 mdash 66ndash3100 250 mdash [15]Seine River estuary France 160ndash314 mdash mdash 67ndash319 mdash mdash [16]Tama River Japan 13ndash3600 mdash mdash 8ndash540 mdash mdash [17]Velino River Italy ndndash6400 mdash mdash ndndash44300 mdash mdash [2]Surface water Taiwan ndndash18500 mdash 9300 1000ndash13500 mdash 4900 [18]Surface water Jiangsu China 556ndash156707 mdash mdash 16ndash58575 mdash mdash [19]Yangtze River mainstream China 3900ndash54730 mdash mdash ndndash35650 mdash mdash [20]Middle and lower Yellow River China 347ndash31800 mdash mdash ndndash26000 mdash mdash [21]Second Songhua River China ndndash1752650 370020 mdash ndndash5616800 mdash 717240 [22]Urban lakes Guangzhou China 87ndash630 170 240 940ndash3600 1990 2030 [11]Xiangjiang River China 620ndash15230 mdash mdash mdash mdash mdash [23]This study 1289ndash65709 6710 17741 525ndash44982 1103 8014

0

500

1000

100001200014000

0

20

40

60

80

100

Raw waterFinished waterRemoval

Rem

oval

()

Con

cent

ratio

ns (n

gL)

DMP DEP DIBP DBP DEHP DNOP

(a)

Raw waterFinished waterRemoval

0

500

1000

1500

2000

100001200014000

0

20

40

60

80

100C

once

ntra

tions

(ng

L)

Rem

oval

()

DMP DEP DIBP DBP DEHP DNOP

(b)

Figure 6 PAEs detected in the water samples from the MPSW (a) and SW (b)

waterworks The removal of PAEs by these two waterworksranged from 258 to 765 which varied significantly with-out stable removal efficienciesThe lower removal efficienciesfor DMP and DNOP were observed in the SW with theremoval less than 30 For both the waterworks no soundremoval efficiencies were obtained for the PAEs indicatingthat the traditional drinking water treatment cannot showgood performance to eliminate these micro pollutants whichhas nothing to do with the type of the water source

Traditional drinking water treatment focuses on dealingwith the particles and colloids in terms of physical processesMany studies of the environmental fates of PAEs have demon-strated that oxidation or microbial action is the principalmechanism for their removal in the aquatic systems [24ndash26]Therefore the treatment process should be the combinationswith the key techniques for removing PAEs from the waterOn the other hand since the removal efficiencies of PAEs by

these advance drinking water treatments in waterworks hasnot been systematically studied to date further research inthis direction would seem to be required

35 Exposure Assessment of PAEs in Water To evaluate thepotential and adverse effects of PAEs quality guidelines forsurface water and drinking water standard were used Theresults indicated that the mean concentrations of DBP andDEHP at levels were well below the reference doses (RfD)regarded as unsafe by the EPA for the surface water Thelevels were not also above the RfD recommended by China(Environmental Quality Standard for SurfaceWater of ChinaGB3838-2002) On the other hand the amounts of DEHPpresent in public water supplies should be lower than thedrinkingwater standard (0006mgL for EPA and 0008mgLfor China) According to the results the concentrations of

Journal of Analytical Methods in Chemistry 7

DEHP in drinkingwater samples from theMPSWwere lowerthan the limited value

PAEs are also considered to be endocrine disruptingchemicals (EDCs) whose effects may not appear until long-term exposure According to the results PAEs were detectedin the drinking water constantly ingested in daily life indi-cating that drinking water is an important source of humanexposure to PAEs contaminants Assuming a daily waterconsumption rate of 2 L and an average body weight of 60 kgfor adults the average daily intake of DEHP DBP and DIBPby way of drinking water from MPSW was calculated to be1158 1352 and 81 ngkgd respectively In comparison thevalues of SW with the water source of the Songhua Riverwere relatively higher with the calculated results of 1353140 and 155 ngkgd for DEHP DBP and DIBP respectivelyIn this study the estimated daily intake levels of DEHPfrom the drinking water were quite lower than the RfDof 20000 ngkgd released by the EPA However some ofPAEs are partly metabolised in the organism and futureexperiments should be focused on determining the potentialeffects of the metabolites [27]

Currently treated water from the Songhua River is fornonpotable uses and MPSW is the exclusive waterworks runfor the water supply of Harbin city However populationgrowth and drought cycle are limited by the availability of rawwater from theMopanshan Reservoir Tomeet the increasingdemand local and regional water authorities have begun acampaign of second water supply project from the SonghuaRiver again which needs the protection of the Songhua Riverand advanced water treatment for the source

4 Conclusions

This study provided the first detailed data on the contami-nation status of 15 PAEs in the water near the MopanshanReservoir The concentration range of 15 PAEs in the sampleswas from 3558 to 92265 ngL with the mean value of29431 ngL DEHP andDBPwere themain pollutants among15 PAEs accounting for the main watershed pollution Theoccurrence and distribution of PAEs from different samplingsites in the water source varied largely suggesting that thespatial distribution of PAEs was site specific In additionthe monitoring of PAEs in the waterworks also showed thatPAEs can be detected in the drinking water and certaintoxicological risks to drinking water consumers were foundThese results reported here contribute to an understandingof how PAE contaminants are distributed in the new watersource and the waterworks in Harbin city as well as forminga basis for further modeling risk assessment and selection ofdrinking water treatment technology

In conclusion the results implied that no urgent reme-diation measures were required with respect to PAEs in thewaters However the ecological and health effects of thesesubstances through drinkingwater at the relatively lower con-centrations still need further notice in light of their possiblebiological magnifications Therefore the long-term sourcecontrol in the water and adding advanced treatment processfor drinking water supplies should be given special attentionin this area

Acknowledgments

This work was supported by the National Natural ScienceFoundation of China (1077029) the Funds for CreativeResearch Groups of China (Grant no 51121062) the NationalNatural Science Foundation of China (51078105) and theOpen Project of the State Key Laboratory of Urban WaterResource and Environment Harbin Institute of Technology(no QA201019)

References

[1] M Nikonorow H Mazur and H Piekacz ldquoEffect of orallyadministered plasticizers and polyvinyl chloride stabilizers inthe ratrdquo Toxicology and Applied Pharmacology vol 26 no 2 pp253ndash259 1973

[2] M Vitali M Guidotti G Macilenti and C Cremisini ldquoPhtha-late esters in freshwaters asmarkers of contamination sourcesmdasha site study in ItalyrdquoEnvironment International vol 23 no 3 pp337ndash347 1997

[3] G Latini C de Felice G Presta et al ldquoIn utero exposure todi-(2-ethylhexyl)phthalate and duration of human pregnancyrdquoEnvironmental Health Perspectives vol 111 no 14 pp 1783ndash17852003

[4] C E Mackintosh J A Maldonado M G Ikonomou and F AP C Gobas ldquoSorption of phthalate esters and PCBs in a marineecosystemrdquo Environmental Science and Technology vol 40 no11 pp 3481ndash3488 2006

[5] M Clara G Windhofer W Hartl et al ldquoOccurrence of phtha-lates in surface runoff untreated and treated wastewater andfate during wastewater treatmentrdquo Chemosphere vol 78 no 9pp 1078ndash1084 2010

[6] M M Abdel Daiem J Rivera-Utrilla R Ocampo-Perez J DMendez-Dıaz andM Sanchez-Polo ldquoEnvironmental impact ofphthalic acid esters and their removal fromwater and sedimentsby different technologiesmdasha reviewrdquo Journal of EnvironmentalManagement vol 109 pp 164ndash178 2012

[7] L Chen Y Zhao L Li B Chen and Y Zhang ldquoExposureassessment of phthalates in non-occupational populations inChinardquo Science of the Total Environment vol 427-428 pp 60ndash69 2012

[8] M J Teil M Blanchard andM Chevreuil ldquoAtmospheric fate ofphthalate esters in an urban area (Paris-France)rdquo Science of theTotal Environment vol 354 no 2-3 pp 212ndash223 2006

[9] P Roslev K Vorkamp J Aarup K Frederiksen and P HNielsen ldquoDegradation of phthalate esters in an activated sludgewastewater treatment plantrdquo Water Research vol 41 no 5 pp969ndash976 2007

[10] J Gasperi S Garnaud V Rocher and R Moilleron ldquoPrioritypollutants in wastewater and combined sewer overflowrdquo Scienceof the Total Environment vol 407 no 1 pp 263ndash272 2008

[11] F Zeng K Cui Z Xie et al ldquoOccurrence of phthalate estersin water and sediment of urban lakes in a subtropical cityGuangzhou South Chinardquo Environment International vol 34no 3 pp 372ndash380 2008

[12] F Zeng K Cui Z Xie et al ldquoPhthalate esters (PAEs) emergingorganic contaminants in agricultural soils in peri-urban areasaround Guangzhou Chinardquo Environmental Pollution vol 156no 2 pp 425ndash434 2008

[13] G Wildbrett ldquoDiffusion of phthalic acid esters from PVC milktubingrdquo Environmental Health Perspectives vol 3 pp 29ndash351973

8 Journal of Analytical Methods in Chemistry

[14] H Fromme T Kuchler T Otto K Pilz J Muller and AWenzel ldquoOccurrence of phthalates and bisphenol A and F inthe environmentrdquoWater Research vol 36 no 6 pp 1429ndash14382002

[15] A D Vethaak J Lahr S M Schrap et al ldquoAn integrated assess-ment of estrogenic contamination and biological effects in theaquatic environment ofTheNetherlandsrdquoChemosphere vol 59no 4 pp 511ndash524 2005

[16] C Dargnat M Blanchard M Chevreuil andM J Teil ldquoOccur-rence of phthalate esters in the Seine River estuary (France)rdquoHydrological Processes vol 23 no 8 pp 1192ndash1201 2009

[17] T Suzuki K Yaguchi S Suzuki and T Suga ldquoMonitoring ofphthalic acid monoesters in river water by solid-phase extrac-tion and GC-MS determinationrdquo Environmental Science andTechnology vol 35 no 18 pp 3757ndash3763 2001

[18] S Y Yuan C Liu C S Liao and B V Chang ldquoOccurrenceand microbial degradation of phthalate esters in Taiwan riversedimentsrdquo Chemosphere vol 49 no 10 pp 1295ndash1299 2002

[19] B Li C Qu and J Bi ldquoIdentification of trace organic pollutantsin drinking water and the associated human health risks inJiangsu Province Chinardquo Bulletin of Environmental Contami-nation and Toxicology pp 1ndash5 2012

[20] F Wang X Xia and Y Sha ldquoDistribution of phthalic acidesters in Wuhan section of the Yangtze River Chinardquo Journalof Hazardous Materials vol 154 no 1ndash3 pp 317ndash324 2008

[21] Y J Sha X H Xia and X Q Xiao ldquoDistribution characters ofphthalic acid ester in the waters middle and lower reaches ofthe Yellow Riverrdquo China Environmental Science vol 26 no 1pp 120ndash124 2006

[22] J Lu L-B Hao C-Z Wang W Li R-J Bai and D YanldquoDistribution characteristics of phthalic acid esters in middleand lower reaches of no 2 Songhua Riverrdquo EnvironmentalScience amp Technology vol 12 article 014 2007

[23] X J Zhu and Y Y Qiu ldquoMeasuring the phthalates of xiangjiangriver using liquid-liquid extraction gas chromatographyrdquoAdvanced Materials Research vol 301 pp 752ndash755 2011

[24] B L Yuan X Z Li and N Graham ldquoAqueous oxida-tion of dimethyl phthalate in a Fe(VI)-TiO

2

-UV reaction sys-temrdquoWater Research vol 42 no 6-7 pp 1413ndash1420 2008

[25] Z Yunrui ZWanpeng L FudongW Jianbing and Y ShaoxialdquoCatalytic activity of RuAl2O3 for ozonation of dimethylphthalate in aqueous solutionrdquo Chemosphere vol 66 no 1 pp145ndash150 2007

[26] H N Gavala U Yenal and B K Ahring ldquoThermal andenzymatic pretreatment of sludge containing phthalate estersprior tomesophilic anaerobic digestionrdquoBiotechnology and Bio-engineering vol 85 no 5 pp 561ndash567 2004

[27] Y Guo Q Wu and K Kannan ldquoPhthalate metabolites in urinefrom China and implications for human exposuresrdquo Environ-ment International vol 37 no 5 pp 893ndash898 2011

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 210653 8 pageshttpdxdoiorg1011552013210653

Research ArticleSimultaneous Determination of Hormonal Residuesin Treated Waters Using Ultrahigh Performance LiquidChromatography-Tandem Mass Spectrometry

Rayco Guedes-Alonso Zoraida Sosa-Ferrera and Joseacute Juan Santana-Rodriacuteguez

Departamento de Quımica Universidad de Las Palmas de Gran Canaria 35017 Las Palmas de Gran Canaria Spain

Correspondence should be addressed to Jose Juan Santana-Rodrıguez jsantanadquiulpgces

Received 28 December 2012 Accepted 7 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Rayco Guedes-Alonso et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

In the last years hormone consumption has increased exponentially Because of that hormone compounds are considered emergingpollutants since several studies have determinted their presence in water influents and effluents of wastewater treatment plants(WWTPs) In this study a quantitative method for the simultaneous determination of oestrogens (estrone 17120573-estradiol estriol17120572-ethinylestradiol and diethylstilbestrol) androgens (testosterone) and progestogens (norgestrel andmegestrol acetate) has beendeveloped to determine these compounds in wastewater samples Due to the very low concentrations of target compounds in theenvironment a solid phase extraction procedure has been optimized and developed to extract and preconcentrate the analytesDetermination and quantification were performed by ultrahigh performance liquid chromatography-tandem mass spectrometry(UHPLC-MSMS) The method developed presents satisfactory limits of detection (between 015 and 935 ngsdotLminus1) good recoveries(between 73 and 90 for the most of compounds) and low relative standard deviations (under 84) Samples from influents andeffluents of two wastewater treatment plants of Gran Canaria (Spain) were analyzed using the proposed method finding severalhormones with concentrations ranged from 5 to 300 ngsdotLminus1

1 Introduction

In general it is supposed that more than 100000 differentchemical compounds can be introduced in the Environmentmany of them in very small quantity However a lot of thesecompounds are not included as pollutants in the legislationAlthough these compounds named emerging pollutants arenot regulated as pollutants they probably will be in the futurebecause of their potential negative effect in the ecosystem For20 years many articles have reported the presence of theseldquonew compoundsrdquo in wastewater [1 2]

The emerging pollutant origin is mainly anthropogenicconsidering that the majority of these compounds are bio-logically active substances that are synthesized to use themin agriculture industry and medicine The main source ofthese emerging pollutants is the residual urbanwaters and thewastewater treatment plants effluents because many of these

WWTPs are not designed or optimized to treat this kind ofcompounds [3]

Hormones are one of the most potent endocrine disrupt-ing compounds as well as are considered also as emergingpollutants Hormones can be differentiated in oestrogensandrogens and progestogens Some of them have limits intheir use but not a specific legislation [4]

The main characteristic of these pollutants is that it isnot necessary to remain in the environment to cause negativeeffects in view of the fact that their constant introduction init offsets their removal or degradation [5]

The steroid hormones help controlling the metabolisminflammations immunological functions water and salt bal-ance sexual development and the capacity of withstandingillnesses [6] The term steroid can be used for naturalhormones produced by the body as well as for artificiallyproduced medicines that increase the natural steroid effect

2 Journal of Analytical Methods in Chemistry

In the last 50 years the natural and synthetic hormoneworldwide consumption has grown as much as in humanmedicine as in cattle farming and they become the mostprescribed medicines [7]

A significant quantity of consumed oestrogens leaves theorganism through excretions For example 17120573-estradiol (E2)is oxidized rapidly becoming an estrone (E1) that can turninto estriol afterwards (E3) Besides the 17120572-ethinyl estradiol(EE) is excreted as conjugated [8]

With regard to emission sources in the first place arethe wastewater treatment plants (WWTPs) [9] and secon-darily cattle waste such as those leachates from dung anduncontrolled dumping [10] Several studies made in theWWTPs have reported that the treatment plants are capableof eliminating around 60 of hormones [11ndash13]

The identification of hormone residues in environmentis of special interest because knowledge of these compoundsis a requirement to take measures in order to regulate andminimize their environmental impact

However measurement of hormone residues is a verydifficult task not only due to the difficulty in measuringvery low concentration but also due to a very complexityof the samples Therefore use of mass spectrometer (MS)as detector coupled with chromatography techniques hasbecome a powerful method for the analysis of these typesof compounds at trace levels [14ndash17] Consequently LC-MSMS is the principally chosen technique One of the mainadvantages of LC-MSMS is its ability to analyze hormoneswithout derivatization (necessary in GC) or the need ofhydrolyze the conjugated form

Due to low level concentration of these compounds inenvironmental water it is necessary to apply an extractionand preconcentration method prior to LC analysis The mostused technique of extraction and preconcentration methodfor liquid samples is the solid phase extraction (SPE) [18ndash20]

The objective of this study is to develop a rapid and simpleprocedure of extraction preconcentration and determina-tion of four steroid oestrogens (estrone (E1) 17120573-estradiol(E2) estriol (E3) and 17120572-ethinylestradiol (EE)) one non-steroidal oestrogen the diethylstilbestrol (DES) one andro-gen the testosterone (TES) and two synthetic progestogensnorgestrel (NOR) and megestrol acetate (MGA) (Table 1)based on solid phase extraction and ultrahigh performanceliquid chromatography-tandem mass spectrometry (SPE-UHPLC-MSMS) The developed method was applied tothe identification and quantification of these compoundsin wastewater samples obtained from the influents andeffluents of two wastewater treatment plants (WWTPs) ofGran Canaria (Spain) They presented different methodsof wastewater treatments WWTP 1 presented a traditionalmethod based on activated sludge while WWTP 2 used amembrane bioreactor technique

2 Materials and Methods

21 Reagents All of the hormonal compounds usedwere pur-chased from Sigma-Aldrich (Madrid Spain) Stock solutionscontaining 1000mgsdotLminus1 of each analyte were prepared by

dissolving the compound inmethanol and the solutionswerestored in glass-stoppered bottles at 4∘C prior to use Workingaqueous standard solutions were prepared daily Ultrapurewater was provided by a Milli-Q system (Millipore BedfordMA USA) HPLC-grade methanol LC-MS methanol andLC-MS water as well as the ammonia and the ammoniumacetate used to adjust the pH of the mobile phases wereobtained from Panreac Quımica (Barcelona Spain)

22 Sample Collection Water samples were collected fromthe effluents of twowastewater treatment plants located in thenorthern area of Gran Canaria in May and August of 2012WWTP 1 used a conventional activated sludge treatmentsystem while WWTP 2 employed a membrane bioreactortreatment system The samples were collected in 2 L amberglass bottles that were rinsed beforehand with methanol andultrapurewater Samples were purified through filtrationwithfibreglass filters and then with 065 120583m membrane filters(Millipore Ireland) The samples were stored in the dark at4∘C and extracted within 48 hours

23 Instrumentation For the SPE optimization the instru-ment used was an ultrahigh performance liquid chromatog-raphy with fluorescence detector (UHPLC-FD) system con-sisting of an ACQUITYQuaternary Solvent Manager (QSM)used to load samples and wash and recondition the analyticalcolumn an autosampler a column manager and a fluores-cence detector with excitation and emission wavelengths of280 and 310 nm respectively all fromWaters (Madrid Spain)

The analysis of wastewater samples was performed ina UHPLC-MSMS system from Waters (Madrid Spain)similar to the described above with a 2777 autosamplerequipped with a 25120583L syringe and a tray to hold 2mLvials and an ACQUITY tandem triple quadrupole (TQD)mass spectrometer with an electrospray ionization (ESI)interface All Waters components (Madrid Spain) werecontrolled using the MassLynx Mass Spectrometry SoftwareElectrospray ionisation parameters were fixed as followsthe capillary voltage was 3 kV in positive mode and minus2 kVin negative mode the source temperature was 150∘C thedesolvation temperature was 500∘C and the desolvation gasflow rate was 1000 Lhr Nitrogen was used as the desolvationgas and argon was employed as the collision gas

The detailed MSMS detection parameters for each hor-monal compound are presented in Table 2 and were opti-mised by the direct injection of a 1mgsdotLminus1 standard solutionof each analyte into the detector at a flow rate of 10 120583Lsdotminminus1

24 Chromatographic Conditions For the SPE optimizationthe analytical column was a 50mm times 21mm ACQUITYUHPLCBEHWaters C

18columnwith a particle size of 17120583m

(Waters Chromatography Barcelona Spain) operating at atemperature of 30∘C Analytes separation was carried outemploying the following gradient starting at 55 45 (vv)water methanol for 1 minute During 3 minutes it changedto 50 50 (vv) and stayed for 25 minutes more Finally cameback to initial conditions in 1 minute and stayed for 15

Journal of Analytical Methods in Chemistry 3

Table 1 List of hormonal compounds pKa values chemical structure and retention times

Compound pKa [21] Structure 119905119877

(min)

E3 Estriol 103

HO

OH

OH

H H

H096

E2 17120573-estradiol 103

HO

OH

H H

H218

EE 17120572-ethinylestradiol 103

HO

HO

H H

H223

E1 Estrone 103

HO

O

H

H H220

DES Diethylstilbestrol 102

HO

OH

235

TES Testosterone 151

OH

OH H

H240

MGA Megestrol acetate

O

O

O

OH

H

H306

NOR Levonorgestrel 131

OH

O

H

H

H

H263

minutes Therefore the analysis took 9 minutes at a flow of05mLsdotminminus1

For the analysis of real samples aUHPLC-MSMS systemwas used The analytical column was the same and themobile phase was water and methanol adjusted with a bufferconsisting in 01 vv ammonia and 15mM of ammoniumacetate The analysis was performed in gradient mode at aflow rate of 03mLsdotminminus1The gradient started at 50 50 (vv)mixture of water methanol which changed to 25 75 (vv) in3 minutes and returned to 50 50 in 1 minute more Finallythe gradient stayed calibrating for another 15 minutes moreThe sample volume injected was 5120583L

3 Results and Discussion

31 Optimization of Solid-Phase Extraction (SPE) There area number of parameters that affect SPE procedure such as

type of sorbent pH ionic strength sample and desorptionvolumes and wash step To optimize these parameters itused Milli-Q water spiked with a solution of fluorescenceoestrogens (estriol 17120573-estradiol and 17120572-ethinylestradiol)to obtain a final concentration of 250120583gsdotLminus1

The first parameter to optimize is the choice of sorbentsince it controls the selectivity affinity and capacity overanalytes In this study the SPE cartridges used were OASISHLB SepPak C

18(both from Waters Madrid Spain) and

BondElut ENV (fromAgilent Madrid Spain) Keeping otherparameters fixed (ionic strength of 0 sample volume of100mL) the cartridges were studied at three different pHs(5 8 and 11) From the results obtained it can be observedthat the better signals are found for SepPak C

18cartridge

(Figure 1)After choosing the optimum cartridge we used an initial

experimental design of 23 to study the influence of pH ionic

4 Journal of Analytical Methods in Chemistry

Table 2 Mass spectrometer parameters for the determination of target analytes

Compound Precursor ion(mz)

Capillary voltage(Ion mode)

Quantification ionmz(collision potential V)

Quantification ionmz(collision potential V)

E3 2872 minus65V (ESI minus) 1710 (37) 1452 (39)E2 2712 minus65V (ESI minus) 1451 (40) 1831 (31)EE 2952 minus60V (ESI minus) 1450 (37) 1589 (33)E1 2692 minus65V (ESI minus) 1450 (36) 1430 (48)DES 2671 minus50V (ESI minus) 2371 (29) 2511 (25)TES 2892 38V (ESI +) 1870 (18) 1040 (21)MGA 3855 30V (ESI +) 2673 (15) 2242 (30)NOR 3132 38V (ESI +) 1090 (26) 2451 (18)

0

500

1000

1500

2000

2500

E3 E2 EE

Peak

area

Cartridge optimizationOASIS HLB pH = 5

OASIS HLB pH = 8

OASIS HLB pH = 11SepPak C18 pH = 5

SepPak C18 pH = 8

SepPak C18 pH = 11BondElut ENV pH = 5

BondElut ENV pH = 8

BondElut ENV pH =11

Figure 1 Optimization of SPE cartridges

strength and sample volume over extraction process Theexperimental design was obtained using Statgraphics Plussoftware 51 and the statistics study was done with IBM SPSSStatistics 19 We assessed two levels and three parameters pH(3 and 8) ionic strength (0 and 30 of NaCl) and samplevolume (50 and 250mL) to obtain the influence of eachparameter and the variable correlation to each other In thisstudy it is observed that the ionic strength and sample volumehad the major influence on the recoveries of the analytesFor that a 32 factorial design to optimize these two variablesat three levels per parameter (0 15 and 30 of NaCl forionic strength and 50 100 y 250mL for sample volume) wasused Figure 2 shows the response surface obtained for theestriol and 17120572-ethinylestradiol The results obtained showedthat an increment of the ionic strength did not producean increase in the response area of the compound and theoptimum volume was 250mL Because of that a solutionwithout salt addition and 250mL of sample volume waschosen Finally the desorption volume (1mLofmethanol and2mL of methanol in one and two steps) and wash-step (5mL

ofMilli-Q water and 5mL ofMilli-Q water with 5 and 10 ofmethanol vv) were assayed to complete the optimization ofthe SPE process The optimum values were 2mL of methanolin one step and 5mL of Milli-Q water without methanolrespectively

In accordance with the obtained results the optimumconditions for SPE procedure were SepPak C

18cartridge

250mL of sample at pH = 8 and 0 of NaCl desorptionwith 2mL of methanol in one step and wash step with5mL of Milli-Q water In these conditions we achieved apreconcentration factor of 125 In Figure 3 a chromatogramwith the optimum conditions is shown where the peaksof all compounds in their corresponding transitions can beobserved

32 Analytical Parameters Because of the SPE optimizationthat was done only with fluorescent compounds (estriol 17120573-estradiol and 17120572-ethinylestradiol) it was necessary to studythe recoveries of all the hormonal compounds using theoptimized SPE-UHPLC-MSMSmethod All the compoundsunder study showed good recoveries over 73 except thediethylstilbestrol with a recovery of 507

A calibration curve was used for the quantification ofthe analytes by diluting the stock solution of each analyteinto the samples to concentrations ranging between 1 and100 120583gsdotLminus1 Analysis was conducted by UHPLC-MSMS andlinear calibration plots for each analyte (1199032 gt 099) wereobtained based on their chromatographic peak areas

The limit of detection (LOD) and the limit of quantifi-cation (LOQ) for each compound were calculated from thesignal-to-noise ratio of each individual peak The LOD wasdefined as the lowest concentration that gave a signal-to-noiseratio that was greater than 3 The LOQ was defined as thelowest concentration that gave a signal to noise ratio that wasgreater than 10The LODs ranged from015 to 935 ngsdotLminus1 andthe LOQs ranged from 049 to 3118 ngsdotLminus1

The performance and reliability of the process werestudied by determining the repeatability of the quantificationresults for all target analytes under the described conditionsusing six samples (119899 = 6) The relative standard deviations(RSDs) were lower than 84 in all cases indicating a

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 8: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 419349 8 pageshttpdxdoiorg1011552013419349

Research ArticleOccurrence and Removal Characteristics of Phthalate Estersfrom Typical Water Sources in Northeast China

Yu Liu Zhonglin Chen and Jimin Shen

State Key Laboratory of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Jimin Shen shenjiminhiteducn

Received 21 December 2012 Accepted 3 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Yu Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The presence of phthalate esters (PAEs) in the environment has gained a considerable attention due to their potential impactson public health This study reports the first data on the occurrence of 15 PAEs in the water near the Mopanshan Reservoirmdashthenew and important water source of Harbin city in Northeast China As drinking water is a major source for human exposureto PAEs the fate of target PAEs in the two waterworks (Mopanshan Waterworks and Seven Waterworks) was also analyzed Theresults demonstrated that the total concentrations of 15 PAEs in the water near the Mopanshan Reservoir were relatively moderateranging from 3558 to 92265 ngL with the mean value of 29431 ngL DBP and DEHP dominated the PAE concentrations whichranged from 525 to 44982 ngL and 1289 to 65709 ngL respectivelyThe occurrence and concentrations of these compoundswereheavily spatially dependent Meanwhile the results on the waterworks samples suggested no significant differences in PAE levelswith the input of the raw waters Without effective and stable removal of PAEs after the conventional drinking water treatment inthe waterworks (258 to 765) the risks posed by PAEs through drinking water ingestion were still existing which should bepaid special attention to the source control in theMopanshan Reservoir and some advanced treatment processes for drinking watersupplies

1 Introduction

Phthalate acid esters a class of chemical compounds mainlyused as plasticizers for polyvinyl chloride (PVC) or to alesser extent other resins in different industrial activities areubiquitous in the environment and have evoked interest inthe past decade due to endocrine disrupting effects and theirpotential impacts on public health [1ndash3]

Worldwide production of PAEs is approximately 6 mil-lion tons per year [4] As PAEs are not chemically boundto the polymeric matrix in soft plastics they can enter theenvironment by losses during manufacturing processes andby leaching or evaporating from final products [5]Thereforethe occurrence and fate of specific PAEs in natural waterenvironments have been observed and also there are a lot ofconsiderable controversies with respect to the safety of PAEsin water [5ndash10]

Six PAE compounds including dimethyl (DMP) diethyl(DEP) dibutyl (DBP) butylbenzyl (BBP) di(2-ethylhexyl)

(DEHP) and di-n-octyl phthalate (DNOP) are classifiedas priority pollutants by the US Environmental ProtectionAgency (EPA) Though the toxicity of PAEs to humans hasnot been well documented for some years the Ministry ofEnvironmental Protection in China has regulated phthalatesas environmental pollutants In addition the standard inChina concerning analytical controls on drinkingwaters doesnot specifically identify any PAEs as organic pollutant indexesto be determined by the new drinking water standard in 2007(Standard for drinking water quality GB5749-2006) whichwas forced to be monitored for the drinking water supplies in2012 Consequently official data about the presence of thesepollutants in the aquatic environment of some cities are notavailable

Harbin the capital of Heilongjiang Province is a typicallyold industrial base and economically developed city with apopulation of over 3million inNortheast China As the newlyenabledwater source forHarbin cityMopanshanwaterworkssupply the whole city with drinking water through long

2 Journal of Analytical Methods in Chemistry

China

HarbinMopanshan

Reservoir

LongfengshanReservoir

Figure 1 Spatial distribution of the 16 sampling sites near the Mopanshan Reservoir in Northeast China

distance transfer from the Mopanshan Reservoir To theauthorsrsquo knowledge the occurrence and fate of PAEs in thewater near this area and its relative waterworks have notpreviously been examined

The objectives of this study were (i) to determine theoccurrence of PAEs and clarify the fate and distribution ofthe pollutants in the water source (ii) to examine the twowaterworks where traditional drinking water treatment stepwas evaluated on the PAEs removal efficiencies and (iii) toevaluate the potential for adverse effects of PAEs on humanhealth Therefore the investigation of PAEs in the water canprovide a valuable record of contamination in Harbin city

2 Materials and Methods

21 Chemical Fifteen PAEs standard mixture includingdimethyl phthalate diethyl phthalate diisobutyl phthalatedi-n-butyl phthalate di(4-methyl-2-pentyl) phthalate di(2-ethoxyethyl) phthalate di-n-amyl phthalate di-n-hexylphthalate butyl benzyl phthalate di(hexyl-2-ethylhexyl)phthalate di(2-n-butoxyethyl) phthalate dicyclohexyl phthal-ate di(2-ethylhexyl) phthalate di-n-nonyl phthalate di-n-octylphthalate at 1000 120583gmL each and surrogate standardsconsisting of diisophenyl phthalate di-n-phenyl phthal-ate and di-n-benzyl phthalate in a mixture solution of500120583gmL each were supplied by AccuStandard Inc Asthe internal standard benzyl benzoate was also purchasedfrom AccuStandard Inc All solvents (acetone hexane anddichloromethane) used were HPLC-grade and were pur-chased from J T Baker Co (USA) Anhydrous sodiumsulfate (Tianjin Chengguang Chemical Reagent Co China)was cleaned at 600∘C for 6 h and then kept in a desiccatorbefore use

22 Sample Collection and Preparation Harbin the capitalof Heilongjiang province in China imports nearly all of itsdrinking water from two sources the Mopanshan Reservoir

Raw water Coagulation sedimentation Filtration Tank

Sampling site Sampling site

Figure 2 Schematic diagram of the waterworks

(long-distance transport project) and the Songhua River (oldwater source)

Water samples from the Mopanshan Reservoir andMopanshan waterwork were collected in 2008 The locationsof the sampling sites near the Mopanshan Reservoir are pre-sented in Figure 1 as a comparison sampling from anotherHarbin water supplymdashSeven waterworks with water sourcefrom the SonghuaRiverwas performed in 2011 In eachwater-works with considering the hydraulic retention time threesets of raw water samples (influent) were taken and thenthe final finished waters (effluent) after the whole treatmentprocess were carried out for the collectionsThe flow diagramof the waterworks is shown in Figure 2

Samples were collected using 20 L glass jars from 05mbelow the water surface During the whole sampling processthe global position system was used to locate the samplingstations (details in Table 1) All samples were transferred tothe laboratory directly after sampling and stored at 4∘C priorto extraction within 2 d

Water samples were filtered under vacuum through glassfiber filters (07 120583mpore sizes) Prior to extraction each sam-ple was spiked with surrogate standards The water sampleswere extracted based on a classical liquid phase extractionmethod (USEPA method 8061) with slight modificationsBriefly 1 L of water samples was placed in a separating funneland extracted by means of mechanical shaking with 150mLdichloromethane and then with filtration on sodium sulfate(about 20 g) the organic extracts were concentrated usinga rotary evaporator The exchange of solvent was done byreplacing dichloromethane with hexane Finally they were

Journal of Analytical Methods in Chemistry 3

Table 1 Detailed descriptions of the sampling locations

Number Sampling site Name Latitude Longitude1 Lalin Jinsan Bridge Mangniu River E127∘0210158405310158401015840 N45∘510158404510158401015840

2 Xingsheng Town Gaojiatun Lalin River E127∘0610158401110158401015840 N44∘5110158405710158401015840

3 Dujia Town Shuguang Lalin River E127∘1010158404410158401015840 N44∘4810158404110158401015840

4 Shanhe Town Taipingchuan Lalin River E127∘1810158403610158401015840 N44∘4310158405010158401015840

5 Xiaoyang Town Qichuankou Lalin River E127∘2310158405410158401015840 N44∘3910158404610158401015840

6 Shahezi Town Mopanshan Reservoir E127∘3810158405910158401015840 N44∘2410158401710158401015840

7 Shahezi Town Gali Lalin River E127∘3510158401710158401015840 N44∘3110158405610158401015840

8 Chonghe Town Changcuizi Mangniu River E127∘4610158403610158401015840 N44∘3510158404610158401015840

9 Chonghe Town Xingguo Mangniu River E127∘3510158401710158401015840 N44∘3110158405710158401015840

10 Longfeng Town Mangniu River E127∘3510158401910158401015840 N44∘4310158404810158401015840

11 Changpu Town Zhonghua Mangniu River E127∘1610158403010158401015840 N45∘110158404210158401015840

12 Erhe Town Shuanghe Mangniu River E127∘1810158403210158401015840 N45∘410158402810158401015840

13 Zhiguang Town Songjiajie Mangniu River E127∘341015840310158401015840 N45∘110158402010158401015840

14 Zhiguang Town Wuxing Mangniu River E127∘2910158402010158401015840 N45∘010158404310158401015840

15 Changpu Town Xingzhuang Mangniu River E127∘1010158404210158401015840 N45∘410158403610158401015840

16 Yingchang Town Xingguang Lalin River E126∘551015840810158401015840 N45∘91015840010158401015840

reduced to 05mL under gentle nitrogen flow The internalstandard was added to the sample prior to instrumentalanalysis

23 Chemical Analysis The extracted compounds weredetermined by gas chromatography coupled to mass spec-trometer analysis as described in other publications [1112] Briefly extracted samples were injected into an Agilent6890 Series GC equipped with a DB-35MS capillary column(Agilent 30m times 025mm id 025120583m film thickness) andan Agilent 5973 MS detector operating in the selective ionmonitoring mode The column temperature was initially setat 70∘C for 1min then ramped at 10∘Cmin to 300∘C andheld constant for 10min The transfer line and the ion sourcetemperature were maintained at 280 and 250∘C respectivelyHelium was used as the carrier gas at a flow rate of 1mLminThe extracts (20 120583L) were injected in splitless mode with aninlet temperature of 300∘C

24 Quality Assurance and Quality Control All glasswarewas properly cleaned with acetone and dichloromethanebefore use Laboratory reagent and instrumental blanks wereanalyzed with each batch of samples to check for possiblecontamination and interferences Only small levels of PAEswere found in procedural blanks in some batches andthe background subtraction was appropriately performed inthe quantification of concentration in the water samplesCalibration curves were obtained from at least 3 replicateanalyses of each standard solution The surrogate standardswere added to all the samples to monitor matrix effectsRecoveries of PAEs ranged from 62 to 112 in the spikedwater and the surrogate recoveries were 751 plusmn 127 fordiisophenyl phthalate 723 plusmn 143 for di-n-phenyl phtha-late and 1026 plusmn 104 for di-n-benzyl phthalate in thewater samples The determination limits ranged from 6 to30 ngL A midpoint calibration check standard was injected

as a check for instrumental drift in sensitivity after every10 samples and a pure solvent (methanol) was injected as acheck for carryover of PAEs from sample to sample All theconcentrations were not corrected for the recoveries of thesurrogate standards

3 Results and Discussion

31 PAEs in Water Source The PAEs in the waters fromthe sampling sites near the Mopanshan Reservoir wereinvestigated and the results are presented in Table 2 Thesum15

PAEs concentrations ranged from 3558 to 92265 ngLwith the geometric mean value of 29431 ngL Among the15 PAEs detected in the waters DIBP DBP and DEHP weremeasured in all the samples with the average concentrationsbeing 1966 8014 and 17741 ngL respectively The threePAE congeners are important and popular addictives inmany industrial products including flexible PVC materialsand household products suggesting the main source of PAEcontaminants in the water [13] The correlations of the con-centration of DEHP DBP and DIBP with the concentrationsof total PAEs in the water samples are shown in Figure 3and a relatively significant correlation between sum

15

PAEs andDEHP concentration was found suggesting the importantpart played by DEHP in total concentrations of PAEs inthe water bodies near the Mopanshan Reservoir In otherwords the contribution of DEHP to total PAEs was higherthan that of other PAE congeners in the water samples Inaddition DMP DEP and DNOP with the mean value of140 284 and 541 ngL respectively only detected at somesampling sites and have also attracted much attention asthe priority pollutants by the China National EnvironmentalMonitoring Center On the contrary the concentrations of6 PAEs (DMEP BMPP BBP DBEP DCHP and DNP) werebelow detection limits in all the water samples near theMopanshan Reservoir which is easily explained in terms ofmuch lower quantities of present use in China

4 Journal of Analytical Methods in Chemistry

0 2000 4000 6000 80000

2000

4000

6000

Con

cent

ratio

ns (n

gL)

DEHP

119903 = 0885 119875 lt 001

sum15PAEs (ngL)

(a)

0 2000 4000 6000 80000

2000

4000

Con

cent

ratio

ns (n

gL)

sum15PAEs (ngL)

DBP

119903 = 0812 119875 lt 001

(b)

1000

500

0

0 2000 4000 6000 8000sum15PAEs (ngL)

DIBP

Con

cent

ratio

ns (n

gL)

119903 = 0724 119875 lt 001

(c)

Figure 3 Correlations of the concentration of the major PAEs (DEHP DBP and DIBP) with the concentrations of total PAEs in the watersamples

Table 2 Concentrations of 15 PAEs in water samples near the Mopanshan Reservoir

PAEs Abbreviation Water (ngL)Range Mean Frequency

Dimethyl phthalate DMP ndndash424 140 816Diethyl phthalate DEP ndndash550 284 1516Diisobutyl phthalate DIBP 400ndash6588 1966 1616Dibutyl phthalate DBP 525ndash44982 8014 1616bis(2-methoxyethyl)phthalate DMEP nd nd 016bis(4-methyl-2-pentyl)phthalate BMPP nd nd 016bis(2-ethoxyethyl)phthalate DEEP ndndash546 128 516Dipentyl phthalate DPP ndndash925 455 1016Dihexyl phthalate DHXP ndndash651 162 516Benzyl butyl phthalate BBP nd nd 016bis(2-n-butoxyethyl)phthalate DBEP nd nd 016Dicyclohexyl phthalate DCHP nd nd 016bis(2-ethylhexyl)phthalate DEHP 1289ndash65709 17741 1616Di-n-octyl phthalate DNOP ndndash4482 541 516Dinonyl phthalate DNP nd nd 016sum15

PAEs 3558ndash92265 29431 mdash

The distribution of 15 PAEs (sum15

PAEs) studied and6 US EPA priority PAEs (sum

6

PAEs including DMP DEPDIBP DBP DEHP and DNOP) in the waters from differentsampling sites are shown in Figure 4 There was an obviousvariation in the total sum

15

PAEs concentrations in water sam-ples near the Mopanshan Reservoir the concentrations ofsum6

PAEs from the same sampling sites varied from 2690 to90860 ngL with an average of 28686 ngL the distributionspectra of which observed for all the sampling sites weresimilar tosum

15

PAEsThe highest levels of PAEs contaminationwere seen on the sampling site 3 followed by some relativelyheavily polluted sites (site 16 13 9 10 and 11) indicating thatthese sites served as important PAE sources and the spatialdistribution of PAEs was site specific The levels in the watersexamined varied over a wide range especially in theMangniu

River near theMopanshan Reservoir (in some case overmorethan one order of magnitude) In general it should be notedthat there might be a relation of PAEs levels with the input oflocal waste such as sewage water food packaging and scrapmaterial near the sampling point which were found duringthe sampling period

32 PAE Congener Profiles in the Water Different PAE pat-terns may indicate different sources of PAEs Measurementof the individual PAE composition is helpful to track thecontaminant source and demonstrate the transport and fateof these compounds in water [11] The relative contributionsof the 9 detectable PAE congeners to thesum

15

PAEs concentra-tions in the water are presented in Figure 5 It is clear thatDEHP was the most abundant in the water samples with

Journal of Analytical Methods in Chemistry 5

0

500

1000

1500

4000

6000

8000

10000

Con

cent

ratio

ns (n

gL)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

sum15PAEssum6PAEs

Figure 4 Spatial distributions of the 16 sampling sites near theMopanshan Reservoir

the exception of site 2 3 and 11 contributions ranging from331 to 963 followed byDBP ranging from 21 to 363The results are consistent with the above data for overallanalysis that DBP and DEHP are the dominant componentsof the PAEs distribution pattern in each sampling site whichreflected the different pattern of plastic contaminant inputduring the sampling period Similarly DIBP and DBP areused in epoxy resins or special adhesive formulations withthe different proportions of these two PAE congeners whichwere also the important indicator of the information pollutedby PAEs for the sampling locations Although the limitedsample number draws only limited conclusions there is stillreason to note that a leaching from the plastic materials intothe runoff water is possible and that water runoff from thecontaminated water is a burden pathway from differentsources of PAEs [14]

33 Comparison with Other Water Bodies Comparison withthe total PAEs concentrations is nevertheless very limited dueto the different analysis compounds However the individualPAE namely DBP and DEHP is by far the most abundantin other researches and it is possible to make a camparisonwith our findings In this case the results of DBP and DEHPconcentrations published in literatures for kinds of waterbodies are presented together in Table 3

The DEHP and DBP concentrations of the present studyshowed to some extent lower concentration levels than thosereported in the other water bodies in China In comparisonthe results were comparable or similar to those from theexaminations described in other foreign countries For exam-ple as shown in Table 3 the DEHP concentrations were sim-ilar to the surface waters from the Netherlands and Italydescribed in the literature Meanwhile these concentrationsin this study were quite lower than the Yangtze River andSecond Songhua River in China

0

20

40

60

80

100

DEEP DPP DHXP DEHP DNOP DBP

DIBP DEP DMP

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

Com

posit

ion

()

Figure 5 PAE composition of thewater samples in 16 sampling sites

In conclusion as compared to the results of other studiesthe waters near the Mopanshan Reservoir were moderatelypolluted by PAEs Therefore there is a definite need to set upa properly planned and systematic approach to water controlnear the Mopanshan Reservoir

34 PAE Levels in the Waterworks The Mopanshan Water-works (MPSW) equipped essentially with the water sourceof the Mopanshan Reservoir has been investigated in orderto assess the fate of the PAEs during the drinking watertreatment process For comparison a sampling campaign forthe determination of PAEs levels in the Seven Waterworks(SW waterworks with the old water source of the SonghuaRiver) was carried out Both waterworks operate coagulationsedimentation and followed by filtration treatment processwhich are typical traditional drinking water treatment

The measured concentrations in the raw and finishedwater of the two investigated waterworks are shown inFigure 6 Six out of fifteen PAEs were detected in the fin-ished water from the two waterworks The detected PAEswere DMP DEP DIBP DBP DEHP and DNOP and theother investigated phthalates are of minor importance withconcentrations all below the limit of detection As showin Figure 6 the measured concentrations of the analyzedPAEs in the finished water of the two waterworks variedstronglyThemost important compound in the finishedwaterwas DEHP with the mean concentration of 34737 and40592 ngL for the MPSW and SW respectively suggestingthe highest relative composition of total PAE concentrationsin the drinking water

For the raw water from the different water sources DMPand DIBP concentrations in the MPSW were much lowerthan the ones in the SW and the concentrations of DEPDBP DEHP andDEHPwere relatively comparable in the two

6 Journal of Analytical Methods in Chemistry

Table 3 Comparison of the concentrations of DEHP and DBP in the water bodies (ngL)

Location DEHP DBP ReferenceRange Median Mean Range Median Mean

Surface water Germany 330ndash97800 2270 mdash 120ndash8800 500 mdash [14]Surface water the Netherlands ndndash5000 320 mdash 66ndash3100 250 mdash [15]Seine River estuary France 160ndash314 mdash mdash 67ndash319 mdash mdash [16]Tama River Japan 13ndash3600 mdash mdash 8ndash540 mdash mdash [17]Velino River Italy ndndash6400 mdash mdash ndndash44300 mdash mdash [2]Surface water Taiwan ndndash18500 mdash 9300 1000ndash13500 mdash 4900 [18]Surface water Jiangsu China 556ndash156707 mdash mdash 16ndash58575 mdash mdash [19]Yangtze River mainstream China 3900ndash54730 mdash mdash ndndash35650 mdash mdash [20]Middle and lower Yellow River China 347ndash31800 mdash mdash ndndash26000 mdash mdash [21]Second Songhua River China ndndash1752650 370020 mdash ndndash5616800 mdash 717240 [22]Urban lakes Guangzhou China 87ndash630 170 240 940ndash3600 1990 2030 [11]Xiangjiang River China 620ndash15230 mdash mdash mdash mdash mdash [23]This study 1289ndash65709 6710 17741 525ndash44982 1103 8014

0

500

1000

100001200014000

0

20

40

60

80

100

Raw waterFinished waterRemoval

Rem

oval

()

Con

cent

ratio

ns (n

gL)

DMP DEP DIBP DBP DEHP DNOP

(a)

Raw waterFinished waterRemoval

0

500

1000

1500

2000

100001200014000

0

20

40

60

80

100C

once

ntra

tions

(ng

L)

Rem

oval

()

DMP DEP DIBP DBP DEHP DNOP

(b)

Figure 6 PAEs detected in the water samples from the MPSW (a) and SW (b)

waterworks The removal of PAEs by these two waterworksranged from 258 to 765 which varied significantly with-out stable removal efficienciesThe lower removal efficienciesfor DMP and DNOP were observed in the SW with theremoval less than 30 For both the waterworks no soundremoval efficiencies were obtained for the PAEs indicatingthat the traditional drinking water treatment cannot showgood performance to eliminate these micro pollutants whichhas nothing to do with the type of the water source

Traditional drinking water treatment focuses on dealingwith the particles and colloids in terms of physical processesMany studies of the environmental fates of PAEs have demon-strated that oxidation or microbial action is the principalmechanism for their removal in the aquatic systems [24ndash26]Therefore the treatment process should be the combinationswith the key techniques for removing PAEs from the waterOn the other hand since the removal efficiencies of PAEs by

these advance drinking water treatments in waterworks hasnot been systematically studied to date further research inthis direction would seem to be required

35 Exposure Assessment of PAEs in Water To evaluate thepotential and adverse effects of PAEs quality guidelines forsurface water and drinking water standard were used Theresults indicated that the mean concentrations of DBP andDEHP at levels were well below the reference doses (RfD)regarded as unsafe by the EPA for the surface water Thelevels were not also above the RfD recommended by China(Environmental Quality Standard for SurfaceWater of ChinaGB3838-2002) On the other hand the amounts of DEHPpresent in public water supplies should be lower than thedrinkingwater standard (0006mgL for EPA and 0008mgLfor China) According to the results the concentrations of

Journal of Analytical Methods in Chemistry 7

DEHP in drinkingwater samples from theMPSWwere lowerthan the limited value

PAEs are also considered to be endocrine disruptingchemicals (EDCs) whose effects may not appear until long-term exposure According to the results PAEs were detectedin the drinking water constantly ingested in daily life indi-cating that drinking water is an important source of humanexposure to PAEs contaminants Assuming a daily waterconsumption rate of 2 L and an average body weight of 60 kgfor adults the average daily intake of DEHP DBP and DIBPby way of drinking water from MPSW was calculated to be1158 1352 and 81 ngkgd respectively In comparison thevalues of SW with the water source of the Songhua Riverwere relatively higher with the calculated results of 1353140 and 155 ngkgd for DEHP DBP and DIBP respectivelyIn this study the estimated daily intake levels of DEHPfrom the drinking water were quite lower than the RfDof 20000 ngkgd released by the EPA However some ofPAEs are partly metabolised in the organism and futureexperiments should be focused on determining the potentialeffects of the metabolites [27]

Currently treated water from the Songhua River is fornonpotable uses and MPSW is the exclusive waterworks runfor the water supply of Harbin city However populationgrowth and drought cycle are limited by the availability of rawwater from theMopanshan Reservoir Tomeet the increasingdemand local and regional water authorities have begun acampaign of second water supply project from the SonghuaRiver again which needs the protection of the Songhua Riverand advanced water treatment for the source

4 Conclusions

This study provided the first detailed data on the contami-nation status of 15 PAEs in the water near the MopanshanReservoir The concentration range of 15 PAEs in the sampleswas from 3558 to 92265 ngL with the mean value of29431 ngL DEHP andDBPwere themain pollutants among15 PAEs accounting for the main watershed pollution Theoccurrence and distribution of PAEs from different samplingsites in the water source varied largely suggesting that thespatial distribution of PAEs was site specific In additionthe monitoring of PAEs in the waterworks also showed thatPAEs can be detected in the drinking water and certaintoxicological risks to drinking water consumers were foundThese results reported here contribute to an understandingof how PAE contaminants are distributed in the new watersource and the waterworks in Harbin city as well as forminga basis for further modeling risk assessment and selection ofdrinking water treatment technology

In conclusion the results implied that no urgent reme-diation measures were required with respect to PAEs in thewaters However the ecological and health effects of thesesubstances through drinkingwater at the relatively lower con-centrations still need further notice in light of their possiblebiological magnifications Therefore the long-term sourcecontrol in the water and adding advanced treatment processfor drinking water supplies should be given special attentionin this area

Acknowledgments

This work was supported by the National Natural ScienceFoundation of China (1077029) the Funds for CreativeResearch Groups of China (Grant no 51121062) the NationalNatural Science Foundation of China (51078105) and theOpen Project of the State Key Laboratory of Urban WaterResource and Environment Harbin Institute of Technology(no QA201019)

References

[1] M Nikonorow H Mazur and H Piekacz ldquoEffect of orallyadministered plasticizers and polyvinyl chloride stabilizers inthe ratrdquo Toxicology and Applied Pharmacology vol 26 no 2 pp253ndash259 1973

[2] M Vitali M Guidotti G Macilenti and C Cremisini ldquoPhtha-late esters in freshwaters asmarkers of contamination sourcesmdasha site study in ItalyrdquoEnvironment International vol 23 no 3 pp337ndash347 1997

[3] G Latini C de Felice G Presta et al ldquoIn utero exposure todi-(2-ethylhexyl)phthalate and duration of human pregnancyrdquoEnvironmental Health Perspectives vol 111 no 14 pp 1783ndash17852003

[4] C E Mackintosh J A Maldonado M G Ikonomou and F AP C Gobas ldquoSorption of phthalate esters and PCBs in a marineecosystemrdquo Environmental Science and Technology vol 40 no11 pp 3481ndash3488 2006

[5] M Clara G Windhofer W Hartl et al ldquoOccurrence of phtha-lates in surface runoff untreated and treated wastewater andfate during wastewater treatmentrdquo Chemosphere vol 78 no 9pp 1078ndash1084 2010

[6] M M Abdel Daiem J Rivera-Utrilla R Ocampo-Perez J DMendez-Dıaz andM Sanchez-Polo ldquoEnvironmental impact ofphthalic acid esters and their removal fromwater and sedimentsby different technologiesmdasha reviewrdquo Journal of EnvironmentalManagement vol 109 pp 164ndash178 2012

[7] L Chen Y Zhao L Li B Chen and Y Zhang ldquoExposureassessment of phthalates in non-occupational populations inChinardquo Science of the Total Environment vol 427-428 pp 60ndash69 2012

[8] M J Teil M Blanchard andM Chevreuil ldquoAtmospheric fate ofphthalate esters in an urban area (Paris-France)rdquo Science of theTotal Environment vol 354 no 2-3 pp 212ndash223 2006

[9] P Roslev K Vorkamp J Aarup K Frederiksen and P HNielsen ldquoDegradation of phthalate esters in an activated sludgewastewater treatment plantrdquo Water Research vol 41 no 5 pp969ndash976 2007

[10] J Gasperi S Garnaud V Rocher and R Moilleron ldquoPrioritypollutants in wastewater and combined sewer overflowrdquo Scienceof the Total Environment vol 407 no 1 pp 263ndash272 2008

[11] F Zeng K Cui Z Xie et al ldquoOccurrence of phthalate estersin water and sediment of urban lakes in a subtropical cityGuangzhou South Chinardquo Environment International vol 34no 3 pp 372ndash380 2008

[12] F Zeng K Cui Z Xie et al ldquoPhthalate esters (PAEs) emergingorganic contaminants in agricultural soils in peri-urban areasaround Guangzhou Chinardquo Environmental Pollution vol 156no 2 pp 425ndash434 2008

[13] G Wildbrett ldquoDiffusion of phthalic acid esters from PVC milktubingrdquo Environmental Health Perspectives vol 3 pp 29ndash351973

8 Journal of Analytical Methods in Chemistry

[14] H Fromme T Kuchler T Otto K Pilz J Muller and AWenzel ldquoOccurrence of phthalates and bisphenol A and F inthe environmentrdquoWater Research vol 36 no 6 pp 1429ndash14382002

[15] A D Vethaak J Lahr S M Schrap et al ldquoAn integrated assess-ment of estrogenic contamination and biological effects in theaquatic environment ofTheNetherlandsrdquoChemosphere vol 59no 4 pp 511ndash524 2005

[16] C Dargnat M Blanchard M Chevreuil andM J Teil ldquoOccur-rence of phthalate esters in the Seine River estuary (France)rdquoHydrological Processes vol 23 no 8 pp 1192ndash1201 2009

[17] T Suzuki K Yaguchi S Suzuki and T Suga ldquoMonitoring ofphthalic acid monoesters in river water by solid-phase extrac-tion and GC-MS determinationrdquo Environmental Science andTechnology vol 35 no 18 pp 3757ndash3763 2001

[18] S Y Yuan C Liu C S Liao and B V Chang ldquoOccurrenceand microbial degradation of phthalate esters in Taiwan riversedimentsrdquo Chemosphere vol 49 no 10 pp 1295ndash1299 2002

[19] B Li C Qu and J Bi ldquoIdentification of trace organic pollutantsin drinking water and the associated human health risks inJiangsu Province Chinardquo Bulletin of Environmental Contami-nation and Toxicology pp 1ndash5 2012

[20] F Wang X Xia and Y Sha ldquoDistribution of phthalic acidesters in Wuhan section of the Yangtze River Chinardquo Journalof Hazardous Materials vol 154 no 1ndash3 pp 317ndash324 2008

[21] Y J Sha X H Xia and X Q Xiao ldquoDistribution characters ofphthalic acid ester in the waters middle and lower reaches ofthe Yellow Riverrdquo China Environmental Science vol 26 no 1pp 120ndash124 2006

[22] J Lu L-B Hao C-Z Wang W Li R-J Bai and D YanldquoDistribution characteristics of phthalic acid esters in middleand lower reaches of no 2 Songhua Riverrdquo EnvironmentalScience amp Technology vol 12 article 014 2007

[23] X J Zhu and Y Y Qiu ldquoMeasuring the phthalates of xiangjiangriver using liquid-liquid extraction gas chromatographyrdquoAdvanced Materials Research vol 301 pp 752ndash755 2011

[24] B L Yuan X Z Li and N Graham ldquoAqueous oxida-tion of dimethyl phthalate in a Fe(VI)-TiO

2

-UV reaction sys-temrdquoWater Research vol 42 no 6-7 pp 1413ndash1420 2008

[25] Z Yunrui ZWanpeng L FudongW Jianbing and Y ShaoxialdquoCatalytic activity of RuAl2O3 for ozonation of dimethylphthalate in aqueous solutionrdquo Chemosphere vol 66 no 1 pp145ndash150 2007

[26] H N Gavala U Yenal and B K Ahring ldquoThermal andenzymatic pretreatment of sludge containing phthalate estersprior tomesophilic anaerobic digestionrdquoBiotechnology and Bio-engineering vol 85 no 5 pp 561ndash567 2004

[27] Y Guo Q Wu and K Kannan ldquoPhthalate metabolites in urinefrom China and implications for human exposuresrdquo Environ-ment International vol 37 no 5 pp 893ndash898 2011

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 210653 8 pageshttpdxdoiorg1011552013210653

Research ArticleSimultaneous Determination of Hormonal Residuesin Treated Waters Using Ultrahigh Performance LiquidChromatography-Tandem Mass Spectrometry

Rayco Guedes-Alonso Zoraida Sosa-Ferrera and Joseacute Juan Santana-Rodriacuteguez

Departamento de Quımica Universidad de Las Palmas de Gran Canaria 35017 Las Palmas de Gran Canaria Spain

Correspondence should be addressed to Jose Juan Santana-Rodrıguez jsantanadquiulpgces

Received 28 December 2012 Accepted 7 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Rayco Guedes-Alonso et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

In the last years hormone consumption has increased exponentially Because of that hormone compounds are considered emergingpollutants since several studies have determinted their presence in water influents and effluents of wastewater treatment plants(WWTPs) In this study a quantitative method for the simultaneous determination of oestrogens (estrone 17120573-estradiol estriol17120572-ethinylestradiol and diethylstilbestrol) androgens (testosterone) and progestogens (norgestrel andmegestrol acetate) has beendeveloped to determine these compounds in wastewater samples Due to the very low concentrations of target compounds in theenvironment a solid phase extraction procedure has been optimized and developed to extract and preconcentrate the analytesDetermination and quantification were performed by ultrahigh performance liquid chromatography-tandem mass spectrometry(UHPLC-MSMS) The method developed presents satisfactory limits of detection (between 015 and 935 ngsdotLminus1) good recoveries(between 73 and 90 for the most of compounds) and low relative standard deviations (under 84) Samples from influents andeffluents of two wastewater treatment plants of Gran Canaria (Spain) were analyzed using the proposed method finding severalhormones with concentrations ranged from 5 to 300 ngsdotLminus1

1 Introduction

In general it is supposed that more than 100000 differentchemical compounds can be introduced in the Environmentmany of them in very small quantity However a lot of thesecompounds are not included as pollutants in the legislationAlthough these compounds named emerging pollutants arenot regulated as pollutants they probably will be in the futurebecause of their potential negative effect in the ecosystem For20 years many articles have reported the presence of theseldquonew compoundsrdquo in wastewater [1 2]

The emerging pollutant origin is mainly anthropogenicconsidering that the majority of these compounds are bio-logically active substances that are synthesized to use themin agriculture industry and medicine The main source ofthese emerging pollutants is the residual urbanwaters and thewastewater treatment plants effluents because many of these

WWTPs are not designed or optimized to treat this kind ofcompounds [3]

Hormones are one of the most potent endocrine disrupt-ing compounds as well as are considered also as emergingpollutants Hormones can be differentiated in oestrogensandrogens and progestogens Some of them have limits intheir use but not a specific legislation [4]

The main characteristic of these pollutants is that it isnot necessary to remain in the environment to cause negativeeffects in view of the fact that their constant introduction init offsets their removal or degradation [5]

The steroid hormones help controlling the metabolisminflammations immunological functions water and salt bal-ance sexual development and the capacity of withstandingillnesses [6] The term steroid can be used for naturalhormones produced by the body as well as for artificiallyproduced medicines that increase the natural steroid effect

2 Journal of Analytical Methods in Chemistry

In the last 50 years the natural and synthetic hormoneworldwide consumption has grown as much as in humanmedicine as in cattle farming and they become the mostprescribed medicines [7]

A significant quantity of consumed oestrogens leaves theorganism through excretions For example 17120573-estradiol (E2)is oxidized rapidly becoming an estrone (E1) that can turninto estriol afterwards (E3) Besides the 17120572-ethinyl estradiol(EE) is excreted as conjugated [8]

With regard to emission sources in the first place arethe wastewater treatment plants (WWTPs) [9] and secon-darily cattle waste such as those leachates from dung anduncontrolled dumping [10] Several studies made in theWWTPs have reported that the treatment plants are capableof eliminating around 60 of hormones [11ndash13]

The identification of hormone residues in environmentis of special interest because knowledge of these compoundsis a requirement to take measures in order to regulate andminimize their environmental impact

However measurement of hormone residues is a verydifficult task not only due to the difficulty in measuringvery low concentration but also due to a very complexityof the samples Therefore use of mass spectrometer (MS)as detector coupled with chromatography techniques hasbecome a powerful method for the analysis of these typesof compounds at trace levels [14ndash17] Consequently LC-MSMS is the principally chosen technique One of the mainadvantages of LC-MSMS is its ability to analyze hormoneswithout derivatization (necessary in GC) or the need ofhydrolyze the conjugated form

Due to low level concentration of these compounds inenvironmental water it is necessary to apply an extractionand preconcentration method prior to LC analysis The mostused technique of extraction and preconcentration methodfor liquid samples is the solid phase extraction (SPE) [18ndash20]

The objective of this study is to develop a rapid and simpleprocedure of extraction preconcentration and determina-tion of four steroid oestrogens (estrone (E1) 17120573-estradiol(E2) estriol (E3) and 17120572-ethinylestradiol (EE)) one non-steroidal oestrogen the diethylstilbestrol (DES) one andro-gen the testosterone (TES) and two synthetic progestogensnorgestrel (NOR) and megestrol acetate (MGA) (Table 1)based on solid phase extraction and ultrahigh performanceliquid chromatography-tandem mass spectrometry (SPE-UHPLC-MSMS) The developed method was applied tothe identification and quantification of these compoundsin wastewater samples obtained from the influents andeffluents of two wastewater treatment plants (WWTPs) ofGran Canaria (Spain) They presented different methodsof wastewater treatments WWTP 1 presented a traditionalmethod based on activated sludge while WWTP 2 used amembrane bioreactor technique

2 Materials and Methods

21 Reagents All of the hormonal compounds usedwere pur-chased from Sigma-Aldrich (Madrid Spain) Stock solutionscontaining 1000mgsdotLminus1 of each analyte were prepared by

dissolving the compound inmethanol and the solutionswerestored in glass-stoppered bottles at 4∘C prior to use Workingaqueous standard solutions were prepared daily Ultrapurewater was provided by a Milli-Q system (Millipore BedfordMA USA) HPLC-grade methanol LC-MS methanol andLC-MS water as well as the ammonia and the ammoniumacetate used to adjust the pH of the mobile phases wereobtained from Panreac Quımica (Barcelona Spain)

22 Sample Collection Water samples were collected fromthe effluents of twowastewater treatment plants located in thenorthern area of Gran Canaria in May and August of 2012WWTP 1 used a conventional activated sludge treatmentsystem while WWTP 2 employed a membrane bioreactortreatment system The samples were collected in 2 L amberglass bottles that were rinsed beforehand with methanol andultrapurewater Samples were purified through filtrationwithfibreglass filters and then with 065 120583m membrane filters(Millipore Ireland) The samples were stored in the dark at4∘C and extracted within 48 hours

23 Instrumentation For the SPE optimization the instru-ment used was an ultrahigh performance liquid chromatog-raphy with fluorescence detector (UHPLC-FD) system con-sisting of an ACQUITYQuaternary Solvent Manager (QSM)used to load samples and wash and recondition the analyticalcolumn an autosampler a column manager and a fluores-cence detector with excitation and emission wavelengths of280 and 310 nm respectively all fromWaters (Madrid Spain)

The analysis of wastewater samples was performed ina UHPLC-MSMS system from Waters (Madrid Spain)similar to the described above with a 2777 autosamplerequipped with a 25120583L syringe and a tray to hold 2mLvials and an ACQUITY tandem triple quadrupole (TQD)mass spectrometer with an electrospray ionization (ESI)interface All Waters components (Madrid Spain) werecontrolled using the MassLynx Mass Spectrometry SoftwareElectrospray ionisation parameters were fixed as followsthe capillary voltage was 3 kV in positive mode and minus2 kVin negative mode the source temperature was 150∘C thedesolvation temperature was 500∘C and the desolvation gasflow rate was 1000 Lhr Nitrogen was used as the desolvationgas and argon was employed as the collision gas

The detailed MSMS detection parameters for each hor-monal compound are presented in Table 2 and were opti-mised by the direct injection of a 1mgsdotLminus1 standard solutionof each analyte into the detector at a flow rate of 10 120583Lsdotminminus1

24 Chromatographic Conditions For the SPE optimizationthe analytical column was a 50mm times 21mm ACQUITYUHPLCBEHWaters C

18columnwith a particle size of 17120583m

(Waters Chromatography Barcelona Spain) operating at atemperature of 30∘C Analytes separation was carried outemploying the following gradient starting at 55 45 (vv)water methanol for 1 minute During 3 minutes it changedto 50 50 (vv) and stayed for 25 minutes more Finally cameback to initial conditions in 1 minute and stayed for 15

Journal of Analytical Methods in Chemistry 3

Table 1 List of hormonal compounds pKa values chemical structure and retention times

Compound pKa [21] Structure 119905119877

(min)

E3 Estriol 103

HO

OH

OH

H H

H096

E2 17120573-estradiol 103

HO

OH

H H

H218

EE 17120572-ethinylestradiol 103

HO

HO

H H

H223

E1 Estrone 103

HO

O

H

H H220

DES Diethylstilbestrol 102

HO

OH

235

TES Testosterone 151

OH

OH H

H240

MGA Megestrol acetate

O

O

O

OH

H

H306

NOR Levonorgestrel 131

OH

O

H

H

H

H263

minutes Therefore the analysis took 9 minutes at a flow of05mLsdotminminus1

For the analysis of real samples aUHPLC-MSMS systemwas used The analytical column was the same and themobile phase was water and methanol adjusted with a bufferconsisting in 01 vv ammonia and 15mM of ammoniumacetate The analysis was performed in gradient mode at aflow rate of 03mLsdotminminus1The gradient started at 50 50 (vv)mixture of water methanol which changed to 25 75 (vv) in3 minutes and returned to 50 50 in 1 minute more Finallythe gradient stayed calibrating for another 15 minutes moreThe sample volume injected was 5120583L

3 Results and Discussion

31 Optimization of Solid-Phase Extraction (SPE) There area number of parameters that affect SPE procedure such as

type of sorbent pH ionic strength sample and desorptionvolumes and wash step To optimize these parameters itused Milli-Q water spiked with a solution of fluorescenceoestrogens (estriol 17120573-estradiol and 17120572-ethinylestradiol)to obtain a final concentration of 250120583gsdotLminus1

The first parameter to optimize is the choice of sorbentsince it controls the selectivity affinity and capacity overanalytes In this study the SPE cartridges used were OASISHLB SepPak C

18(both from Waters Madrid Spain) and

BondElut ENV (fromAgilent Madrid Spain) Keeping otherparameters fixed (ionic strength of 0 sample volume of100mL) the cartridges were studied at three different pHs(5 8 and 11) From the results obtained it can be observedthat the better signals are found for SepPak C

18cartridge

(Figure 1)After choosing the optimum cartridge we used an initial

experimental design of 23 to study the influence of pH ionic

4 Journal of Analytical Methods in Chemistry

Table 2 Mass spectrometer parameters for the determination of target analytes

Compound Precursor ion(mz)

Capillary voltage(Ion mode)

Quantification ionmz(collision potential V)

Quantification ionmz(collision potential V)

E3 2872 minus65V (ESI minus) 1710 (37) 1452 (39)E2 2712 minus65V (ESI minus) 1451 (40) 1831 (31)EE 2952 minus60V (ESI minus) 1450 (37) 1589 (33)E1 2692 minus65V (ESI minus) 1450 (36) 1430 (48)DES 2671 minus50V (ESI minus) 2371 (29) 2511 (25)TES 2892 38V (ESI +) 1870 (18) 1040 (21)MGA 3855 30V (ESI +) 2673 (15) 2242 (30)NOR 3132 38V (ESI +) 1090 (26) 2451 (18)

0

500

1000

1500

2000

2500

E3 E2 EE

Peak

area

Cartridge optimizationOASIS HLB pH = 5

OASIS HLB pH = 8

OASIS HLB pH = 11SepPak C18 pH = 5

SepPak C18 pH = 8

SepPak C18 pH = 11BondElut ENV pH = 5

BondElut ENV pH = 8

BondElut ENV pH =11

Figure 1 Optimization of SPE cartridges

strength and sample volume over extraction process Theexperimental design was obtained using Statgraphics Plussoftware 51 and the statistics study was done with IBM SPSSStatistics 19 We assessed two levels and three parameters pH(3 and 8) ionic strength (0 and 30 of NaCl) and samplevolume (50 and 250mL) to obtain the influence of eachparameter and the variable correlation to each other In thisstudy it is observed that the ionic strength and sample volumehad the major influence on the recoveries of the analytesFor that a 32 factorial design to optimize these two variablesat three levels per parameter (0 15 and 30 of NaCl forionic strength and 50 100 y 250mL for sample volume) wasused Figure 2 shows the response surface obtained for theestriol and 17120572-ethinylestradiol The results obtained showedthat an increment of the ionic strength did not producean increase in the response area of the compound and theoptimum volume was 250mL Because of that a solutionwithout salt addition and 250mL of sample volume waschosen Finally the desorption volume (1mLofmethanol and2mL of methanol in one and two steps) and wash-step (5mL

ofMilli-Q water and 5mL ofMilli-Q water with 5 and 10 ofmethanol vv) were assayed to complete the optimization ofthe SPE process The optimum values were 2mL of methanolin one step and 5mL of Milli-Q water without methanolrespectively

In accordance with the obtained results the optimumconditions for SPE procedure were SepPak C

18cartridge

250mL of sample at pH = 8 and 0 of NaCl desorptionwith 2mL of methanol in one step and wash step with5mL of Milli-Q water In these conditions we achieved apreconcentration factor of 125 In Figure 3 a chromatogramwith the optimum conditions is shown where the peaksof all compounds in their corresponding transitions can beobserved

32 Analytical Parameters Because of the SPE optimizationthat was done only with fluorescent compounds (estriol 17120573-estradiol and 17120572-ethinylestradiol) it was necessary to studythe recoveries of all the hormonal compounds using theoptimized SPE-UHPLC-MSMSmethod All the compoundsunder study showed good recoveries over 73 except thediethylstilbestrol with a recovery of 507

A calibration curve was used for the quantification ofthe analytes by diluting the stock solution of each analyteinto the samples to concentrations ranging between 1 and100 120583gsdotLminus1 Analysis was conducted by UHPLC-MSMS andlinear calibration plots for each analyte (1199032 gt 099) wereobtained based on their chromatographic peak areas

The limit of detection (LOD) and the limit of quantifi-cation (LOQ) for each compound were calculated from thesignal-to-noise ratio of each individual peak The LOD wasdefined as the lowest concentration that gave a signal-to-noiseratio that was greater than 3 The LOQ was defined as thelowest concentration that gave a signal to noise ratio that wasgreater than 10The LODs ranged from015 to 935 ngsdotLminus1 andthe LOQs ranged from 049 to 3118 ngsdotLminus1

The performance and reliability of the process werestudied by determining the repeatability of the quantificationresults for all target analytes under the described conditionsusing six samples (119899 = 6) The relative standard deviations(RSDs) were lower than 84 in all cases indicating a

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 9: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

2 Journal of Analytical Methods in Chemistry

China

HarbinMopanshan

Reservoir

LongfengshanReservoir

Figure 1 Spatial distribution of the 16 sampling sites near the Mopanshan Reservoir in Northeast China

distance transfer from the Mopanshan Reservoir To theauthorsrsquo knowledge the occurrence and fate of PAEs in thewater near this area and its relative waterworks have notpreviously been examined

The objectives of this study were (i) to determine theoccurrence of PAEs and clarify the fate and distribution ofthe pollutants in the water source (ii) to examine the twowaterworks where traditional drinking water treatment stepwas evaluated on the PAEs removal efficiencies and (iii) toevaluate the potential for adverse effects of PAEs on humanhealth Therefore the investigation of PAEs in the water canprovide a valuable record of contamination in Harbin city

2 Materials and Methods

21 Chemical Fifteen PAEs standard mixture includingdimethyl phthalate diethyl phthalate diisobutyl phthalatedi-n-butyl phthalate di(4-methyl-2-pentyl) phthalate di(2-ethoxyethyl) phthalate di-n-amyl phthalate di-n-hexylphthalate butyl benzyl phthalate di(hexyl-2-ethylhexyl)phthalate di(2-n-butoxyethyl) phthalate dicyclohexyl phthal-ate di(2-ethylhexyl) phthalate di-n-nonyl phthalate di-n-octylphthalate at 1000 120583gmL each and surrogate standardsconsisting of diisophenyl phthalate di-n-phenyl phthal-ate and di-n-benzyl phthalate in a mixture solution of500120583gmL each were supplied by AccuStandard Inc Asthe internal standard benzyl benzoate was also purchasedfrom AccuStandard Inc All solvents (acetone hexane anddichloromethane) used were HPLC-grade and were pur-chased from J T Baker Co (USA) Anhydrous sodiumsulfate (Tianjin Chengguang Chemical Reagent Co China)was cleaned at 600∘C for 6 h and then kept in a desiccatorbefore use

22 Sample Collection and Preparation Harbin the capitalof Heilongjiang province in China imports nearly all of itsdrinking water from two sources the Mopanshan Reservoir

Raw water Coagulation sedimentation Filtration Tank

Sampling site Sampling site

Figure 2 Schematic diagram of the waterworks

(long-distance transport project) and the Songhua River (oldwater source)

Water samples from the Mopanshan Reservoir andMopanshan waterwork were collected in 2008 The locationsof the sampling sites near the Mopanshan Reservoir are pre-sented in Figure 1 as a comparison sampling from anotherHarbin water supplymdashSeven waterworks with water sourcefrom the SonghuaRiverwas performed in 2011 In eachwater-works with considering the hydraulic retention time threesets of raw water samples (influent) were taken and thenthe final finished waters (effluent) after the whole treatmentprocess were carried out for the collectionsThe flow diagramof the waterworks is shown in Figure 2

Samples were collected using 20 L glass jars from 05mbelow the water surface During the whole sampling processthe global position system was used to locate the samplingstations (details in Table 1) All samples were transferred tothe laboratory directly after sampling and stored at 4∘C priorto extraction within 2 d

Water samples were filtered under vacuum through glassfiber filters (07 120583mpore sizes) Prior to extraction each sam-ple was spiked with surrogate standards The water sampleswere extracted based on a classical liquid phase extractionmethod (USEPA method 8061) with slight modificationsBriefly 1 L of water samples was placed in a separating funneland extracted by means of mechanical shaking with 150mLdichloromethane and then with filtration on sodium sulfate(about 20 g) the organic extracts were concentrated usinga rotary evaporator The exchange of solvent was done byreplacing dichloromethane with hexane Finally they were

Journal of Analytical Methods in Chemistry 3

Table 1 Detailed descriptions of the sampling locations

Number Sampling site Name Latitude Longitude1 Lalin Jinsan Bridge Mangniu River E127∘0210158405310158401015840 N45∘510158404510158401015840

2 Xingsheng Town Gaojiatun Lalin River E127∘0610158401110158401015840 N44∘5110158405710158401015840

3 Dujia Town Shuguang Lalin River E127∘1010158404410158401015840 N44∘4810158404110158401015840

4 Shanhe Town Taipingchuan Lalin River E127∘1810158403610158401015840 N44∘4310158405010158401015840

5 Xiaoyang Town Qichuankou Lalin River E127∘2310158405410158401015840 N44∘3910158404610158401015840

6 Shahezi Town Mopanshan Reservoir E127∘3810158405910158401015840 N44∘2410158401710158401015840

7 Shahezi Town Gali Lalin River E127∘3510158401710158401015840 N44∘3110158405610158401015840

8 Chonghe Town Changcuizi Mangniu River E127∘4610158403610158401015840 N44∘3510158404610158401015840

9 Chonghe Town Xingguo Mangniu River E127∘3510158401710158401015840 N44∘3110158405710158401015840

10 Longfeng Town Mangniu River E127∘3510158401910158401015840 N44∘4310158404810158401015840

11 Changpu Town Zhonghua Mangniu River E127∘1610158403010158401015840 N45∘110158404210158401015840

12 Erhe Town Shuanghe Mangniu River E127∘1810158403210158401015840 N45∘410158402810158401015840

13 Zhiguang Town Songjiajie Mangniu River E127∘341015840310158401015840 N45∘110158402010158401015840

14 Zhiguang Town Wuxing Mangniu River E127∘2910158402010158401015840 N45∘010158404310158401015840

15 Changpu Town Xingzhuang Mangniu River E127∘1010158404210158401015840 N45∘410158403610158401015840

16 Yingchang Town Xingguang Lalin River E126∘551015840810158401015840 N45∘91015840010158401015840

reduced to 05mL under gentle nitrogen flow The internalstandard was added to the sample prior to instrumentalanalysis

23 Chemical Analysis The extracted compounds weredetermined by gas chromatography coupled to mass spec-trometer analysis as described in other publications [1112] Briefly extracted samples were injected into an Agilent6890 Series GC equipped with a DB-35MS capillary column(Agilent 30m times 025mm id 025120583m film thickness) andan Agilent 5973 MS detector operating in the selective ionmonitoring mode The column temperature was initially setat 70∘C for 1min then ramped at 10∘Cmin to 300∘C andheld constant for 10min The transfer line and the ion sourcetemperature were maintained at 280 and 250∘C respectivelyHelium was used as the carrier gas at a flow rate of 1mLminThe extracts (20 120583L) were injected in splitless mode with aninlet temperature of 300∘C

24 Quality Assurance and Quality Control All glasswarewas properly cleaned with acetone and dichloromethanebefore use Laboratory reagent and instrumental blanks wereanalyzed with each batch of samples to check for possiblecontamination and interferences Only small levels of PAEswere found in procedural blanks in some batches andthe background subtraction was appropriately performed inthe quantification of concentration in the water samplesCalibration curves were obtained from at least 3 replicateanalyses of each standard solution The surrogate standardswere added to all the samples to monitor matrix effectsRecoveries of PAEs ranged from 62 to 112 in the spikedwater and the surrogate recoveries were 751 plusmn 127 fordiisophenyl phthalate 723 plusmn 143 for di-n-phenyl phtha-late and 1026 plusmn 104 for di-n-benzyl phthalate in thewater samples The determination limits ranged from 6 to30 ngL A midpoint calibration check standard was injected

as a check for instrumental drift in sensitivity after every10 samples and a pure solvent (methanol) was injected as acheck for carryover of PAEs from sample to sample All theconcentrations were not corrected for the recoveries of thesurrogate standards

3 Results and Discussion

31 PAEs in Water Source The PAEs in the waters fromthe sampling sites near the Mopanshan Reservoir wereinvestigated and the results are presented in Table 2 Thesum15

PAEs concentrations ranged from 3558 to 92265 ngLwith the geometric mean value of 29431 ngL Among the15 PAEs detected in the waters DIBP DBP and DEHP weremeasured in all the samples with the average concentrationsbeing 1966 8014 and 17741 ngL respectively The threePAE congeners are important and popular addictives inmany industrial products including flexible PVC materialsand household products suggesting the main source of PAEcontaminants in the water [13] The correlations of the con-centration of DEHP DBP and DIBP with the concentrationsof total PAEs in the water samples are shown in Figure 3and a relatively significant correlation between sum

15

PAEs andDEHP concentration was found suggesting the importantpart played by DEHP in total concentrations of PAEs inthe water bodies near the Mopanshan Reservoir In otherwords the contribution of DEHP to total PAEs was higherthan that of other PAE congeners in the water samples Inaddition DMP DEP and DNOP with the mean value of140 284 and 541 ngL respectively only detected at somesampling sites and have also attracted much attention asthe priority pollutants by the China National EnvironmentalMonitoring Center On the contrary the concentrations of6 PAEs (DMEP BMPP BBP DBEP DCHP and DNP) werebelow detection limits in all the water samples near theMopanshan Reservoir which is easily explained in terms ofmuch lower quantities of present use in China

4 Journal of Analytical Methods in Chemistry

0 2000 4000 6000 80000

2000

4000

6000

Con

cent

ratio

ns (n

gL)

DEHP

119903 = 0885 119875 lt 001

sum15PAEs (ngL)

(a)

0 2000 4000 6000 80000

2000

4000

Con

cent

ratio

ns (n

gL)

sum15PAEs (ngL)

DBP

119903 = 0812 119875 lt 001

(b)

1000

500

0

0 2000 4000 6000 8000sum15PAEs (ngL)

DIBP

Con

cent

ratio

ns (n

gL)

119903 = 0724 119875 lt 001

(c)

Figure 3 Correlations of the concentration of the major PAEs (DEHP DBP and DIBP) with the concentrations of total PAEs in the watersamples

Table 2 Concentrations of 15 PAEs in water samples near the Mopanshan Reservoir

PAEs Abbreviation Water (ngL)Range Mean Frequency

Dimethyl phthalate DMP ndndash424 140 816Diethyl phthalate DEP ndndash550 284 1516Diisobutyl phthalate DIBP 400ndash6588 1966 1616Dibutyl phthalate DBP 525ndash44982 8014 1616bis(2-methoxyethyl)phthalate DMEP nd nd 016bis(4-methyl-2-pentyl)phthalate BMPP nd nd 016bis(2-ethoxyethyl)phthalate DEEP ndndash546 128 516Dipentyl phthalate DPP ndndash925 455 1016Dihexyl phthalate DHXP ndndash651 162 516Benzyl butyl phthalate BBP nd nd 016bis(2-n-butoxyethyl)phthalate DBEP nd nd 016Dicyclohexyl phthalate DCHP nd nd 016bis(2-ethylhexyl)phthalate DEHP 1289ndash65709 17741 1616Di-n-octyl phthalate DNOP ndndash4482 541 516Dinonyl phthalate DNP nd nd 016sum15

PAEs 3558ndash92265 29431 mdash

The distribution of 15 PAEs (sum15

PAEs) studied and6 US EPA priority PAEs (sum

6

PAEs including DMP DEPDIBP DBP DEHP and DNOP) in the waters from differentsampling sites are shown in Figure 4 There was an obviousvariation in the total sum

15

PAEs concentrations in water sam-ples near the Mopanshan Reservoir the concentrations ofsum6

PAEs from the same sampling sites varied from 2690 to90860 ngL with an average of 28686 ngL the distributionspectra of which observed for all the sampling sites weresimilar tosum

15

PAEsThe highest levels of PAEs contaminationwere seen on the sampling site 3 followed by some relativelyheavily polluted sites (site 16 13 9 10 and 11) indicating thatthese sites served as important PAE sources and the spatialdistribution of PAEs was site specific The levels in the watersexamined varied over a wide range especially in theMangniu

River near theMopanshan Reservoir (in some case overmorethan one order of magnitude) In general it should be notedthat there might be a relation of PAEs levels with the input oflocal waste such as sewage water food packaging and scrapmaterial near the sampling point which were found duringthe sampling period

32 PAE Congener Profiles in the Water Different PAE pat-terns may indicate different sources of PAEs Measurementof the individual PAE composition is helpful to track thecontaminant source and demonstrate the transport and fateof these compounds in water [11] The relative contributionsof the 9 detectable PAE congeners to thesum

15

PAEs concentra-tions in the water are presented in Figure 5 It is clear thatDEHP was the most abundant in the water samples with

Journal of Analytical Methods in Chemistry 5

0

500

1000

1500

4000

6000

8000

10000

Con

cent

ratio

ns (n

gL)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

sum15PAEssum6PAEs

Figure 4 Spatial distributions of the 16 sampling sites near theMopanshan Reservoir

the exception of site 2 3 and 11 contributions ranging from331 to 963 followed byDBP ranging from 21 to 363The results are consistent with the above data for overallanalysis that DBP and DEHP are the dominant componentsof the PAEs distribution pattern in each sampling site whichreflected the different pattern of plastic contaminant inputduring the sampling period Similarly DIBP and DBP areused in epoxy resins or special adhesive formulations withthe different proportions of these two PAE congeners whichwere also the important indicator of the information pollutedby PAEs for the sampling locations Although the limitedsample number draws only limited conclusions there is stillreason to note that a leaching from the plastic materials intothe runoff water is possible and that water runoff from thecontaminated water is a burden pathway from differentsources of PAEs [14]

33 Comparison with Other Water Bodies Comparison withthe total PAEs concentrations is nevertheless very limited dueto the different analysis compounds However the individualPAE namely DBP and DEHP is by far the most abundantin other researches and it is possible to make a camparisonwith our findings In this case the results of DBP and DEHPconcentrations published in literatures for kinds of waterbodies are presented together in Table 3

The DEHP and DBP concentrations of the present studyshowed to some extent lower concentration levels than thosereported in the other water bodies in China In comparisonthe results were comparable or similar to those from theexaminations described in other foreign countries For exam-ple as shown in Table 3 the DEHP concentrations were sim-ilar to the surface waters from the Netherlands and Italydescribed in the literature Meanwhile these concentrationsin this study were quite lower than the Yangtze River andSecond Songhua River in China

0

20

40

60

80

100

DEEP DPP DHXP DEHP DNOP DBP

DIBP DEP DMP

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

Com

posit

ion

()

Figure 5 PAE composition of thewater samples in 16 sampling sites

In conclusion as compared to the results of other studiesthe waters near the Mopanshan Reservoir were moderatelypolluted by PAEs Therefore there is a definite need to set upa properly planned and systematic approach to water controlnear the Mopanshan Reservoir

34 PAE Levels in the Waterworks The Mopanshan Water-works (MPSW) equipped essentially with the water sourceof the Mopanshan Reservoir has been investigated in orderto assess the fate of the PAEs during the drinking watertreatment process For comparison a sampling campaign forthe determination of PAEs levels in the Seven Waterworks(SW waterworks with the old water source of the SonghuaRiver) was carried out Both waterworks operate coagulationsedimentation and followed by filtration treatment processwhich are typical traditional drinking water treatment

The measured concentrations in the raw and finishedwater of the two investigated waterworks are shown inFigure 6 Six out of fifteen PAEs were detected in the fin-ished water from the two waterworks The detected PAEswere DMP DEP DIBP DBP DEHP and DNOP and theother investigated phthalates are of minor importance withconcentrations all below the limit of detection As showin Figure 6 the measured concentrations of the analyzedPAEs in the finished water of the two waterworks variedstronglyThemost important compound in the finishedwaterwas DEHP with the mean concentration of 34737 and40592 ngL for the MPSW and SW respectively suggestingthe highest relative composition of total PAE concentrationsin the drinking water

For the raw water from the different water sources DMPand DIBP concentrations in the MPSW were much lowerthan the ones in the SW and the concentrations of DEPDBP DEHP andDEHPwere relatively comparable in the two

6 Journal of Analytical Methods in Chemistry

Table 3 Comparison of the concentrations of DEHP and DBP in the water bodies (ngL)

Location DEHP DBP ReferenceRange Median Mean Range Median Mean

Surface water Germany 330ndash97800 2270 mdash 120ndash8800 500 mdash [14]Surface water the Netherlands ndndash5000 320 mdash 66ndash3100 250 mdash [15]Seine River estuary France 160ndash314 mdash mdash 67ndash319 mdash mdash [16]Tama River Japan 13ndash3600 mdash mdash 8ndash540 mdash mdash [17]Velino River Italy ndndash6400 mdash mdash ndndash44300 mdash mdash [2]Surface water Taiwan ndndash18500 mdash 9300 1000ndash13500 mdash 4900 [18]Surface water Jiangsu China 556ndash156707 mdash mdash 16ndash58575 mdash mdash [19]Yangtze River mainstream China 3900ndash54730 mdash mdash ndndash35650 mdash mdash [20]Middle and lower Yellow River China 347ndash31800 mdash mdash ndndash26000 mdash mdash [21]Second Songhua River China ndndash1752650 370020 mdash ndndash5616800 mdash 717240 [22]Urban lakes Guangzhou China 87ndash630 170 240 940ndash3600 1990 2030 [11]Xiangjiang River China 620ndash15230 mdash mdash mdash mdash mdash [23]This study 1289ndash65709 6710 17741 525ndash44982 1103 8014

0

500

1000

100001200014000

0

20

40

60

80

100

Raw waterFinished waterRemoval

Rem

oval

()

Con

cent

ratio

ns (n

gL)

DMP DEP DIBP DBP DEHP DNOP

(a)

Raw waterFinished waterRemoval

0

500

1000

1500

2000

100001200014000

0

20

40

60

80

100C

once

ntra

tions

(ng

L)

Rem

oval

()

DMP DEP DIBP DBP DEHP DNOP

(b)

Figure 6 PAEs detected in the water samples from the MPSW (a) and SW (b)

waterworks The removal of PAEs by these two waterworksranged from 258 to 765 which varied significantly with-out stable removal efficienciesThe lower removal efficienciesfor DMP and DNOP were observed in the SW with theremoval less than 30 For both the waterworks no soundremoval efficiencies were obtained for the PAEs indicatingthat the traditional drinking water treatment cannot showgood performance to eliminate these micro pollutants whichhas nothing to do with the type of the water source

Traditional drinking water treatment focuses on dealingwith the particles and colloids in terms of physical processesMany studies of the environmental fates of PAEs have demon-strated that oxidation or microbial action is the principalmechanism for their removal in the aquatic systems [24ndash26]Therefore the treatment process should be the combinationswith the key techniques for removing PAEs from the waterOn the other hand since the removal efficiencies of PAEs by

these advance drinking water treatments in waterworks hasnot been systematically studied to date further research inthis direction would seem to be required

35 Exposure Assessment of PAEs in Water To evaluate thepotential and adverse effects of PAEs quality guidelines forsurface water and drinking water standard were used Theresults indicated that the mean concentrations of DBP andDEHP at levels were well below the reference doses (RfD)regarded as unsafe by the EPA for the surface water Thelevels were not also above the RfD recommended by China(Environmental Quality Standard for SurfaceWater of ChinaGB3838-2002) On the other hand the amounts of DEHPpresent in public water supplies should be lower than thedrinkingwater standard (0006mgL for EPA and 0008mgLfor China) According to the results the concentrations of

Journal of Analytical Methods in Chemistry 7

DEHP in drinkingwater samples from theMPSWwere lowerthan the limited value

PAEs are also considered to be endocrine disruptingchemicals (EDCs) whose effects may not appear until long-term exposure According to the results PAEs were detectedin the drinking water constantly ingested in daily life indi-cating that drinking water is an important source of humanexposure to PAEs contaminants Assuming a daily waterconsumption rate of 2 L and an average body weight of 60 kgfor adults the average daily intake of DEHP DBP and DIBPby way of drinking water from MPSW was calculated to be1158 1352 and 81 ngkgd respectively In comparison thevalues of SW with the water source of the Songhua Riverwere relatively higher with the calculated results of 1353140 and 155 ngkgd for DEHP DBP and DIBP respectivelyIn this study the estimated daily intake levels of DEHPfrom the drinking water were quite lower than the RfDof 20000 ngkgd released by the EPA However some ofPAEs are partly metabolised in the organism and futureexperiments should be focused on determining the potentialeffects of the metabolites [27]

Currently treated water from the Songhua River is fornonpotable uses and MPSW is the exclusive waterworks runfor the water supply of Harbin city However populationgrowth and drought cycle are limited by the availability of rawwater from theMopanshan Reservoir Tomeet the increasingdemand local and regional water authorities have begun acampaign of second water supply project from the SonghuaRiver again which needs the protection of the Songhua Riverand advanced water treatment for the source

4 Conclusions

This study provided the first detailed data on the contami-nation status of 15 PAEs in the water near the MopanshanReservoir The concentration range of 15 PAEs in the sampleswas from 3558 to 92265 ngL with the mean value of29431 ngL DEHP andDBPwere themain pollutants among15 PAEs accounting for the main watershed pollution Theoccurrence and distribution of PAEs from different samplingsites in the water source varied largely suggesting that thespatial distribution of PAEs was site specific In additionthe monitoring of PAEs in the waterworks also showed thatPAEs can be detected in the drinking water and certaintoxicological risks to drinking water consumers were foundThese results reported here contribute to an understandingof how PAE contaminants are distributed in the new watersource and the waterworks in Harbin city as well as forminga basis for further modeling risk assessment and selection ofdrinking water treatment technology

In conclusion the results implied that no urgent reme-diation measures were required with respect to PAEs in thewaters However the ecological and health effects of thesesubstances through drinkingwater at the relatively lower con-centrations still need further notice in light of their possiblebiological magnifications Therefore the long-term sourcecontrol in the water and adding advanced treatment processfor drinking water supplies should be given special attentionin this area

Acknowledgments

This work was supported by the National Natural ScienceFoundation of China (1077029) the Funds for CreativeResearch Groups of China (Grant no 51121062) the NationalNatural Science Foundation of China (51078105) and theOpen Project of the State Key Laboratory of Urban WaterResource and Environment Harbin Institute of Technology(no QA201019)

References

[1] M Nikonorow H Mazur and H Piekacz ldquoEffect of orallyadministered plasticizers and polyvinyl chloride stabilizers inthe ratrdquo Toxicology and Applied Pharmacology vol 26 no 2 pp253ndash259 1973

[2] M Vitali M Guidotti G Macilenti and C Cremisini ldquoPhtha-late esters in freshwaters asmarkers of contamination sourcesmdasha site study in ItalyrdquoEnvironment International vol 23 no 3 pp337ndash347 1997

[3] G Latini C de Felice G Presta et al ldquoIn utero exposure todi-(2-ethylhexyl)phthalate and duration of human pregnancyrdquoEnvironmental Health Perspectives vol 111 no 14 pp 1783ndash17852003

[4] C E Mackintosh J A Maldonado M G Ikonomou and F AP C Gobas ldquoSorption of phthalate esters and PCBs in a marineecosystemrdquo Environmental Science and Technology vol 40 no11 pp 3481ndash3488 2006

[5] M Clara G Windhofer W Hartl et al ldquoOccurrence of phtha-lates in surface runoff untreated and treated wastewater andfate during wastewater treatmentrdquo Chemosphere vol 78 no 9pp 1078ndash1084 2010

[6] M M Abdel Daiem J Rivera-Utrilla R Ocampo-Perez J DMendez-Dıaz andM Sanchez-Polo ldquoEnvironmental impact ofphthalic acid esters and their removal fromwater and sedimentsby different technologiesmdasha reviewrdquo Journal of EnvironmentalManagement vol 109 pp 164ndash178 2012

[7] L Chen Y Zhao L Li B Chen and Y Zhang ldquoExposureassessment of phthalates in non-occupational populations inChinardquo Science of the Total Environment vol 427-428 pp 60ndash69 2012

[8] M J Teil M Blanchard andM Chevreuil ldquoAtmospheric fate ofphthalate esters in an urban area (Paris-France)rdquo Science of theTotal Environment vol 354 no 2-3 pp 212ndash223 2006

[9] P Roslev K Vorkamp J Aarup K Frederiksen and P HNielsen ldquoDegradation of phthalate esters in an activated sludgewastewater treatment plantrdquo Water Research vol 41 no 5 pp969ndash976 2007

[10] J Gasperi S Garnaud V Rocher and R Moilleron ldquoPrioritypollutants in wastewater and combined sewer overflowrdquo Scienceof the Total Environment vol 407 no 1 pp 263ndash272 2008

[11] F Zeng K Cui Z Xie et al ldquoOccurrence of phthalate estersin water and sediment of urban lakes in a subtropical cityGuangzhou South Chinardquo Environment International vol 34no 3 pp 372ndash380 2008

[12] F Zeng K Cui Z Xie et al ldquoPhthalate esters (PAEs) emergingorganic contaminants in agricultural soils in peri-urban areasaround Guangzhou Chinardquo Environmental Pollution vol 156no 2 pp 425ndash434 2008

[13] G Wildbrett ldquoDiffusion of phthalic acid esters from PVC milktubingrdquo Environmental Health Perspectives vol 3 pp 29ndash351973

8 Journal of Analytical Methods in Chemistry

[14] H Fromme T Kuchler T Otto K Pilz J Muller and AWenzel ldquoOccurrence of phthalates and bisphenol A and F inthe environmentrdquoWater Research vol 36 no 6 pp 1429ndash14382002

[15] A D Vethaak J Lahr S M Schrap et al ldquoAn integrated assess-ment of estrogenic contamination and biological effects in theaquatic environment ofTheNetherlandsrdquoChemosphere vol 59no 4 pp 511ndash524 2005

[16] C Dargnat M Blanchard M Chevreuil andM J Teil ldquoOccur-rence of phthalate esters in the Seine River estuary (France)rdquoHydrological Processes vol 23 no 8 pp 1192ndash1201 2009

[17] T Suzuki K Yaguchi S Suzuki and T Suga ldquoMonitoring ofphthalic acid monoesters in river water by solid-phase extrac-tion and GC-MS determinationrdquo Environmental Science andTechnology vol 35 no 18 pp 3757ndash3763 2001

[18] S Y Yuan C Liu C S Liao and B V Chang ldquoOccurrenceand microbial degradation of phthalate esters in Taiwan riversedimentsrdquo Chemosphere vol 49 no 10 pp 1295ndash1299 2002

[19] B Li C Qu and J Bi ldquoIdentification of trace organic pollutantsin drinking water and the associated human health risks inJiangsu Province Chinardquo Bulletin of Environmental Contami-nation and Toxicology pp 1ndash5 2012

[20] F Wang X Xia and Y Sha ldquoDistribution of phthalic acidesters in Wuhan section of the Yangtze River Chinardquo Journalof Hazardous Materials vol 154 no 1ndash3 pp 317ndash324 2008

[21] Y J Sha X H Xia and X Q Xiao ldquoDistribution characters ofphthalic acid ester in the waters middle and lower reaches ofthe Yellow Riverrdquo China Environmental Science vol 26 no 1pp 120ndash124 2006

[22] J Lu L-B Hao C-Z Wang W Li R-J Bai and D YanldquoDistribution characteristics of phthalic acid esters in middleand lower reaches of no 2 Songhua Riverrdquo EnvironmentalScience amp Technology vol 12 article 014 2007

[23] X J Zhu and Y Y Qiu ldquoMeasuring the phthalates of xiangjiangriver using liquid-liquid extraction gas chromatographyrdquoAdvanced Materials Research vol 301 pp 752ndash755 2011

[24] B L Yuan X Z Li and N Graham ldquoAqueous oxida-tion of dimethyl phthalate in a Fe(VI)-TiO

2

-UV reaction sys-temrdquoWater Research vol 42 no 6-7 pp 1413ndash1420 2008

[25] Z Yunrui ZWanpeng L FudongW Jianbing and Y ShaoxialdquoCatalytic activity of RuAl2O3 for ozonation of dimethylphthalate in aqueous solutionrdquo Chemosphere vol 66 no 1 pp145ndash150 2007

[26] H N Gavala U Yenal and B K Ahring ldquoThermal andenzymatic pretreatment of sludge containing phthalate estersprior tomesophilic anaerobic digestionrdquoBiotechnology and Bio-engineering vol 85 no 5 pp 561ndash567 2004

[27] Y Guo Q Wu and K Kannan ldquoPhthalate metabolites in urinefrom China and implications for human exposuresrdquo Environ-ment International vol 37 no 5 pp 893ndash898 2011

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 210653 8 pageshttpdxdoiorg1011552013210653

Research ArticleSimultaneous Determination of Hormonal Residuesin Treated Waters Using Ultrahigh Performance LiquidChromatography-Tandem Mass Spectrometry

Rayco Guedes-Alonso Zoraida Sosa-Ferrera and Joseacute Juan Santana-Rodriacuteguez

Departamento de Quımica Universidad de Las Palmas de Gran Canaria 35017 Las Palmas de Gran Canaria Spain

Correspondence should be addressed to Jose Juan Santana-Rodrıguez jsantanadquiulpgces

Received 28 December 2012 Accepted 7 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Rayco Guedes-Alonso et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

In the last years hormone consumption has increased exponentially Because of that hormone compounds are considered emergingpollutants since several studies have determinted their presence in water influents and effluents of wastewater treatment plants(WWTPs) In this study a quantitative method for the simultaneous determination of oestrogens (estrone 17120573-estradiol estriol17120572-ethinylestradiol and diethylstilbestrol) androgens (testosterone) and progestogens (norgestrel andmegestrol acetate) has beendeveloped to determine these compounds in wastewater samples Due to the very low concentrations of target compounds in theenvironment a solid phase extraction procedure has been optimized and developed to extract and preconcentrate the analytesDetermination and quantification were performed by ultrahigh performance liquid chromatography-tandem mass spectrometry(UHPLC-MSMS) The method developed presents satisfactory limits of detection (between 015 and 935 ngsdotLminus1) good recoveries(between 73 and 90 for the most of compounds) and low relative standard deviations (under 84) Samples from influents andeffluents of two wastewater treatment plants of Gran Canaria (Spain) were analyzed using the proposed method finding severalhormones with concentrations ranged from 5 to 300 ngsdotLminus1

1 Introduction

In general it is supposed that more than 100000 differentchemical compounds can be introduced in the Environmentmany of them in very small quantity However a lot of thesecompounds are not included as pollutants in the legislationAlthough these compounds named emerging pollutants arenot regulated as pollutants they probably will be in the futurebecause of their potential negative effect in the ecosystem For20 years many articles have reported the presence of theseldquonew compoundsrdquo in wastewater [1 2]

The emerging pollutant origin is mainly anthropogenicconsidering that the majority of these compounds are bio-logically active substances that are synthesized to use themin agriculture industry and medicine The main source ofthese emerging pollutants is the residual urbanwaters and thewastewater treatment plants effluents because many of these

WWTPs are not designed or optimized to treat this kind ofcompounds [3]

Hormones are one of the most potent endocrine disrupt-ing compounds as well as are considered also as emergingpollutants Hormones can be differentiated in oestrogensandrogens and progestogens Some of them have limits intheir use but not a specific legislation [4]

The main characteristic of these pollutants is that it isnot necessary to remain in the environment to cause negativeeffects in view of the fact that their constant introduction init offsets their removal or degradation [5]

The steroid hormones help controlling the metabolisminflammations immunological functions water and salt bal-ance sexual development and the capacity of withstandingillnesses [6] The term steroid can be used for naturalhormones produced by the body as well as for artificiallyproduced medicines that increase the natural steroid effect

2 Journal of Analytical Methods in Chemistry

In the last 50 years the natural and synthetic hormoneworldwide consumption has grown as much as in humanmedicine as in cattle farming and they become the mostprescribed medicines [7]

A significant quantity of consumed oestrogens leaves theorganism through excretions For example 17120573-estradiol (E2)is oxidized rapidly becoming an estrone (E1) that can turninto estriol afterwards (E3) Besides the 17120572-ethinyl estradiol(EE) is excreted as conjugated [8]

With regard to emission sources in the first place arethe wastewater treatment plants (WWTPs) [9] and secon-darily cattle waste such as those leachates from dung anduncontrolled dumping [10] Several studies made in theWWTPs have reported that the treatment plants are capableof eliminating around 60 of hormones [11ndash13]

The identification of hormone residues in environmentis of special interest because knowledge of these compoundsis a requirement to take measures in order to regulate andminimize their environmental impact

However measurement of hormone residues is a verydifficult task not only due to the difficulty in measuringvery low concentration but also due to a very complexityof the samples Therefore use of mass spectrometer (MS)as detector coupled with chromatography techniques hasbecome a powerful method for the analysis of these typesof compounds at trace levels [14ndash17] Consequently LC-MSMS is the principally chosen technique One of the mainadvantages of LC-MSMS is its ability to analyze hormoneswithout derivatization (necessary in GC) or the need ofhydrolyze the conjugated form

Due to low level concentration of these compounds inenvironmental water it is necessary to apply an extractionand preconcentration method prior to LC analysis The mostused technique of extraction and preconcentration methodfor liquid samples is the solid phase extraction (SPE) [18ndash20]

The objective of this study is to develop a rapid and simpleprocedure of extraction preconcentration and determina-tion of four steroid oestrogens (estrone (E1) 17120573-estradiol(E2) estriol (E3) and 17120572-ethinylestradiol (EE)) one non-steroidal oestrogen the diethylstilbestrol (DES) one andro-gen the testosterone (TES) and two synthetic progestogensnorgestrel (NOR) and megestrol acetate (MGA) (Table 1)based on solid phase extraction and ultrahigh performanceliquid chromatography-tandem mass spectrometry (SPE-UHPLC-MSMS) The developed method was applied tothe identification and quantification of these compoundsin wastewater samples obtained from the influents andeffluents of two wastewater treatment plants (WWTPs) ofGran Canaria (Spain) They presented different methodsof wastewater treatments WWTP 1 presented a traditionalmethod based on activated sludge while WWTP 2 used amembrane bioreactor technique

2 Materials and Methods

21 Reagents All of the hormonal compounds usedwere pur-chased from Sigma-Aldrich (Madrid Spain) Stock solutionscontaining 1000mgsdotLminus1 of each analyte were prepared by

dissolving the compound inmethanol and the solutionswerestored in glass-stoppered bottles at 4∘C prior to use Workingaqueous standard solutions were prepared daily Ultrapurewater was provided by a Milli-Q system (Millipore BedfordMA USA) HPLC-grade methanol LC-MS methanol andLC-MS water as well as the ammonia and the ammoniumacetate used to adjust the pH of the mobile phases wereobtained from Panreac Quımica (Barcelona Spain)

22 Sample Collection Water samples were collected fromthe effluents of twowastewater treatment plants located in thenorthern area of Gran Canaria in May and August of 2012WWTP 1 used a conventional activated sludge treatmentsystem while WWTP 2 employed a membrane bioreactortreatment system The samples were collected in 2 L amberglass bottles that were rinsed beforehand with methanol andultrapurewater Samples were purified through filtrationwithfibreglass filters and then with 065 120583m membrane filters(Millipore Ireland) The samples were stored in the dark at4∘C and extracted within 48 hours

23 Instrumentation For the SPE optimization the instru-ment used was an ultrahigh performance liquid chromatog-raphy with fluorescence detector (UHPLC-FD) system con-sisting of an ACQUITYQuaternary Solvent Manager (QSM)used to load samples and wash and recondition the analyticalcolumn an autosampler a column manager and a fluores-cence detector with excitation and emission wavelengths of280 and 310 nm respectively all fromWaters (Madrid Spain)

The analysis of wastewater samples was performed ina UHPLC-MSMS system from Waters (Madrid Spain)similar to the described above with a 2777 autosamplerequipped with a 25120583L syringe and a tray to hold 2mLvials and an ACQUITY tandem triple quadrupole (TQD)mass spectrometer with an electrospray ionization (ESI)interface All Waters components (Madrid Spain) werecontrolled using the MassLynx Mass Spectrometry SoftwareElectrospray ionisation parameters were fixed as followsthe capillary voltage was 3 kV in positive mode and minus2 kVin negative mode the source temperature was 150∘C thedesolvation temperature was 500∘C and the desolvation gasflow rate was 1000 Lhr Nitrogen was used as the desolvationgas and argon was employed as the collision gas

The detailed MSMS detection parameters for each hor-monal compound are presented in Table 2 and were opti-mised by the direct injection of a 1mgsdotLminus1 standard solutionof each analyte into the detector at a flow rate of 10 120583Lsdotminminus1

24 Chromatographic Conditions For the SPE optimizationthe analytical column was a 50mm times 21mm ACQUITYUHPLCBEHWaters C

18columnwith a particle size of 17120583m

(Waters Chromatography Barcelona Spain) operating at atemperature of 30∘C Analytes separation was carried outemploying the following gradient starting at 55 45 (vv)water methanol for 1 minute During 3 minutes it changedto 50 50 (vv) and stayed for 25 minutes more Finally cameback to initial conditions in 1 minute and stayed for 15

Journal of Analytical Methods in Chemistry 3

Table 1 List of hormonal compounds pKa values chemical structure and retention times

Compound pKa [21] Structure 119905119877

(min)

E3 Estriol 103

HO

OH

OH

H H

H096

E2 17120573-estradiol 103

HO

OH

H H

H218

EE 17120572-ethinylestradiol 103

HO

HO

H H

H223

E1 Estrone 103

HO

O

H

H H220

DES Diethylstilbestrol 102

HO

OH

235

TES Testosterone 151

OH

OH H

H240

MGA Megestrol acetate

O

O

O

OH

H

H306

NOR Levonorgestrel 131

OH

O

H

H

H

H263

minutes Therefore the analysis took 9 minutes at a flow of05mLsdotminminus1

For the analysis of real samples aUHPLC-MSMS systemwas used The analytical column was the same and themobile phase was water and methanol adjusted with a bufferconsisting in 01 vv ammonia and 15mM of ammoniumacetate The analysis was performed in gradient mode at aflow rate of 03mLsdotminminus1The gradient started at 50 50 (vv)mixture of water methanol which changed to 25 75 (vv) in3 minutes and returned to 50 50 in 1 minute more Finallythe gradient stayed calibrating for another 15 minutes moreThe sample volume injected was 5120583L

3 Results and Discussion

31 Optimization of Solid-Phase Extraction (SPE) There area number of parameters that affect SPE procedure such as

type of sorbent pH ionic strength sample and desorptionvolumes and wash step To optimize these parameters itused Milli-Q water spiked with a solution of fluorescenceoestrogens (estriol 17120573-estradiol and 17120572-ethinylestradiol)to obtain a final concentration of 250120583gsdotLminus1

The first parameter to optimize is the choice of sorbentsince it controls the selectivity affinity and capacity overanalytes In this study the SPE cartridges used were OASISHLB SepPak C

18(both from Waters Madrid Spain) and

BondElut ENV (fromAgilent Madrid Spain) Keeping otherparameters fixed (ionic strength of 0 sample volume of100mL) the cartridges were studied at three different pHs(5 8 and 11) From the results obtained it can be observedthat the better signals are found for SepPak C

18cartridge

(Figure 1)After choosing the optimum cartridge we used an initial

experimental design of 23 to study the influence of pH ionic

4 Journal of Analytical Methods in Chemistry

Table 2 Mass spectrometer parameters for the determination of target analytes

Compound Precursor ion(mz)

Capillary voltage(Ion mode)

Quantification ionmz(collision potential V)

Quantification ionmz(collision potential V)

E3 2872 minus65V (ESI minus) 1710 (37) 1452 (39)E2 2712 minus65V (ESI minus) 1451 (40) 1831 (31)EE 2952 minus60V (ESI minus) 1450 (37) 1589 (33)E1 2692 minus65V (ESI minus) 1450 (36) 1430 (48)DES 2671 minus50V (ESI minus) 2371 (29) 2511 (25)TES 2892 38V (ESI +) 1870 (18) 1040 (21)MGA 3855 30V (ESI +) 2673 (15) 2242 (30)NOR 3132 38V (ESI +) 1090 (26) 2451 (18)

0

500

1000

1500

2000

2500

E3 E2 EE

Peak

area

Cartridge optimizationOASIS HLB pH = 5

OASIS HLB pH = 8

OASIS HLB pH = 11SepPak C18 pH = 5

SepPak C18 pH = 8

SepPak C18 pH = 11BondElut ENV pH = 5

BondElut ENV pH = 8

BondElut ENV pH =11

Figure 1 Optimization of SPE cartridges

strength and sample volume over extraction process Theexperimental design was obtained using Statgraphics Plussoftware 51 and the statistics study was done with IBM SPSSStatistics 19 We assessed two levels and three parameters pH(3 and 8) ionic strength (0 and 30 of NaCl) and samplevolume (50 and 250mL) to obtain the influence of eachparameter and the variable correlation to each other In thisstudy it is observed that the ionic strength and sample volumehad the major influence on the recoveries of the analytesFor that a 32 factorial design to optimize these two variablesat three levels per parameter (0 15 and 30 of NaCl forionic strength and 50 100 y 250mL for sample volume) wasused Figure 2 shows the response surface obtained for theestriol and 17120572-ethinylestradiol The results obtained showedthat an increment of the ionic strength did not producean increase in the response area of the compound and theoptimum volume was 250mL Because of that a solutionwithout salt addition and 250mL of sample volume waschosen Finally the desorption volume (1mLofmethanol and2mL of methanol in one and two steps) and wash-step (5mL

ofMilli-Q water and 5mL ofMilli-Q water with 5 and 10 ofmethanol vv) were assayed to complete the optimization ofthe SPE process The optimum values were 2mL of methanolin one step and 5mL of Milli-Q water without methanolrespectively

In accordance with the obtained results the optimumconditions for SPE procedure were SepPak C

18cartridge

250mL of sample at pH = 8 and 0 of NaCl desorptionwith 2mL of methanol in one step and wash step with5mL of Milli-Q water In these conditions we achieved apreconcentration factor of 125 In Figure 3 a chromatogramwith the optimum conditions is shown where the peaksof all compounds in their corresponding transitions can beobserved

32 Analytical Parameters Because of the SPE optimizationthat was done only with fluorescent compounds (estriol 17120573-estradiol and 17120572-ethinylestradiol) it was necessary to studythe recoveries of all the hormonal compounds using theoptimized SPE-UHPLC-MSMSmethod All the compoundsunder study showed good recoveries over 73 except thediethylstilbestrol with a recovery of 507

A calibration curve was used for the quantification ofthe analytes by diluting the stock solution of each analyteinto the samples to concentrations ranging between 1 and100 120583gsdotLminus1 Analysis was conducted by UHPLC-MSMS andlinear calibration plots for each analyte (1199032 gt 099) wereobtained based on their chromatographic peak areas

The limit of detection (LOD) and the limit of quantifi-cation (LOQ) for each compound were calculated from thesignal-to-noise ratio of each individual peak The LOD wasdefined as the lowest concentration that gave a signal-to-noiseratio that was greater than 3 The LOQ was defined as thelowest concentration that gave a signal to noise ratio that wasgreater than 10The LODs ranged from015 to 935 ngsdotLminus1 andthe LOQs ranged from 049 to 3118 ngsdotLminus1

The performance and reliability of the process werestudied by determining the repeatability of the quantificationresults for all target analytes under the described conditionsusing six samples (119899 = 6) The relative standard deviations(RSDs) were lower than 84 in all cases indicating a

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 10: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Journal of Analytical Methods in Chemistry 3

Table 1 Detailed descriptions of the sampling locations

Number Sampling site Name Latitude Longitude1 Lalin Jinsan Bridge Mangniu River E127∘0210158405310158401015840 N45∘510158404510158401015840

2 Xingsheng Town Gaojiatun Lalin River E127∘0610158401110158401015840 N44∘5110158405710158401015840

3 Dujia Town Shuguang Lalin River E127∘1010158404410158401015840 N44∘4810158404110158401015840

4 Shanhe Town Taipingchuan Lalin River E127∘1810158403610158401015840 N44∘4310158405010158401015840

5 Xiaoyang Town Qichuankou Lalin River E127∘2310158405410158401015840 N44∘3910158404610158401015840

6 Shahezi Town Mopanshan Reservoir E127∘3810158405910158401015840 N44∘2410158401710158401015840

7 Shahezi Town Gali Lalin River E127∘3510158401710158401015840 N44∘3110158405610158401015840

8 Chonghe Town Changcuizi Mangniu River E127∘4610158403610158401015840 N44∘3510158404610158401015840

9 Chonghe Town Xingguo Mangniu River E127∘3510158401710158401015840 N44∘3110158405710158401015840

10 Longfeng Town Mangniu River E127∘3510158401910158401015840 N44∘4310158404810158401015840

11 Changpu Town Zhonghua Mangniu River E127∘1610158403010158401015840 N45∘110158404210158401015840

12 Erhe Town Shuanghe Mangniu River E127∘1810158403210158401015840 N45∘410158402810158401015840

13 Zhiguang Town Songjiajie Mangniu River E127∘341015840310158401015840 N45∘110158402010158401015840

14 Zhiguang Town Wuxing Mangniu River E127∘2910158402010158401015840 N45∘010158404310158401015840

15 Changpu Town Xingzhuang Mangniu River E127∘1010158404210158401015840 N45∘410158403610158401015840

16 Yingchang Town Xingguang Lalin River E126∘551015840810158401015840 N45∘91015840010158401015840

reduced to 05mL under gentle nitrogen flow The internalstandard was added to the sample prior to instrumentalanalysis

23 Chemical Analysis The extracted compounds weredetermined by gas chromatography coupled to mass spec-trometer analysis as described in other publications [1112] Briefly extracted samples were injected into an Agilent6890 Series GC equipped with a DB-35MS capillary column(Agilent 30m times 025mm id 025120583m film thickness) andan Agilent 5973 MS detector operating in the selective ionmonitoring mode The column temperature was initially setat 70∘C for 1min then ramped at 10∘Cmin to 300∘C andheld constant for 10min The transfer line and the ion sourcetemperature were maintained at 280 and 250∘C respectivelyHelium was used as the carrier gas at a flow rate of 1mLminThe extracts (20 120583L) were injected in splitless mode with aninlet temperature of 300∘C

24 Quality Assurance and Quality Control All glasswarewas properly cleaned with acetone and dichloromethanebefore use Laboratory reagent and instrumental blanks wereanalyzed with each batch of samples to check for possiblecontamination and interferences Only small levels of PAEswere found in procedural blanks in some batches andthe background subtraction was appropriately performed inthe quantification of concentration in the water samplesCalibration curves were obtained from at least 3 replicateanalyses of each standard solution The surrogate standardswere added to all the samples to monitor matrix effectsRecoveries of PAEs ranged from 62 to 112 in the spikedwater and the surrogate recoveries were 751 plusmn 127 fordiisophenyl phthalate 723 plusmn 143 for di-n-phenyl phtha-late and 1026 plusmn 104 for di-n-benzyl phthalate in thewater samples The determination limits ranged from 6 to30 ngL A midpoint calibration check standard was injected

as a check for instrumental drift in sensitivity after every10 samples and a pure solvent (methanol) was injected as acheck for carryover of PAEs from sample to sample All theconcentrations were not corrected for the recoveries of thesurrogate standards

3 Results and Discussion

31 PAEs in Water Source The PAEs in the waters fromthe sampling sites near the Mopanshan Reservoir wereinvestigated and the results are presented in Table 2 Thesum15

PAEs concentrations ranged from 3558 to 92265 ngLwith the geometric mean value of 29431 ngL Among the15 PAEs detected in the waters DIBP DBP and DEHP weremeasured in all the samples with the average concentrationsbeing 1966 8014 and 17741 ngL respectively The threePAE congeners are important and popular addictives inmany industrial products including flexible PVC materialsand household products suggesting the main source of PAEcontaminants in the water [13] The correlations of the con-centration of DEHP DBP and DIBP with the concentrationsof total PAEs in the water samples are shown in Figure 3and a relatively significant correlation between sum

15

PAEs andDEHP concentration was found suggesting the importantpart played by DEHP in total concentrations of PAEs inthe water bodies near the Mopanshan Reservoir In otherwords the contribution of DEHP to total PAEs was higherthan that of other PAE congeners in the water samples Inaddition DMP DEP and DNOP with the mean value of140 284 and 541 ngL respectively only detected at somesampling sites and have also attracted much attention asthe priority pollutants by the China National EnvironmentalMonitoring Center On the contrary the concentrations of6 PAEs (DMEP BMPP BBP DBEP DCHP and DNP) werebelow detection limits in all the water samples near theMopanshan Reservoir which is easily explained in terms ofmuch lower quantities of present use in China

4 Journal of Analytical Methods in Chemistry

0 2000 4000 6000 80000

2000

4000

6000

Con

cent

ratio

ns (n

gL)

DEHP

119903 = 0885 119875 lt 001

sum15PAEs (ngL)

(a)

0 2000 4000 6000 80000

2000

4000

Con

cent

ratio

ns (n

gL)

sum15PAEs (ngL)

DBP

119903 = 0812 119875 lt 001

(b)

1000

500

0

0 2000 4000 6000 8000sum15PAEs (ngL)

DIBP

Con

cent

ratio

ns (n

gL)

119903 = 0724 119875 lt 001

(c)

Figure 3 Correlations of the concentration of the major PAEs (DEHP DBP and DIBP) with the concentrations of total PAEs in the watersamples

Table 2 Concentrations of 15 PAEs in water samples near the Mopanshan Reservoir

PAEs Abbreviation Water (ngL)Range Mean Frequency

Dimethyl phthalate DMP ndndash424 140 816Diethyl phthalate DEP ndndash550 284 1516Diisobutyl phthalate DIBP 400ndash6588 1966 1616Dibutyl phthalate DBP 525ndash44982 8014 1616bis(2-methoxyethyl)phthalate DMEP nd nd 016bis(4-methyl-2-pentyl)phthalate BMPP nd nd 016bis(2-ethoxyethyl)phthalate DEEP ndndash546 128 516Dipentyl phthalate DPP ndndash925 455 1016Dihexyl phthalate DHXP ndndash651 162 516Benzyl butyl phthalate BBP nd nd 016bis(2-n-butoxyethyl)phthalate DBEP nd nd 016Dicyclohexyl phthalate DCHP nd nd 016bis(2-ethylhexyl)phthalate DEHP 1289ndash65709 17741 1616Di-n-octyl phthalate DNOP ndndash4482 541 516Dinonyl phthalate DNP nd nd 016sum15

PAEs 3558ndash92265 29431 mdash

The distribution of 15 PAEs (sum15

PAEs) studied and6 US EPA priority PAEs (sum

6

PAEs including DMP DEPDIBP DBP DEHP and DNOP) in the waters from differentsampling sites are shown in Figure 4 There was an obviousvariation in the total sum

15

PAEs concentrations in water sam-ples near the Mopanshan Reservoir the concentrations ofsum6

PAEs from the same sampling sites varied from 2690 to90860 ngL with an average of 28686 ngL the distributionspectra of which observed for all the sampling sites weresimilar tosum

15

PAEsThe highest levels of PAEs contaminationwere seen on the sampling site 3 followed by some relativelyheavily polluted sites (site 16 13 9 10 and 11) indicating thatthese sites served as important PAE sources and the spatialdistribution of PAEs was site specific The levels in the watersexamined varied over a wide range especially in theMangniu

River near theMopanshan Reservoir (in some case overmorethan one order of magnitude) In general it should be notedthat there might be a relation of PAEs levels with the input oflocal waste such as sewage water food packaging and scrapmaterial near the sampling point which were found duringthe sampling period

32 PAE Congener Profiles in the Water Different PAE pat-terns may indicate different sources of PAEs Measurementof the individual PAE composition is helpful to track thecontaminant source and demonstrate the transport and fateof these compounds in water [11] The relative contributionsof the 9 detectable PAE congeners to thesum

15

PAEs concentra-tions in the water are presented in Figure 5 It is clear thatDEHP was the most abundant in the water samples with

Journal of Analytical Methods in Chemistry 5

0

500

1000

1500

4000

6000

8000

10000

Con

cent

ratio

ns (n

gL)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

sum15PAEssum6PAEs

Figure 4 Spatial distributions of the 16 sampling sites near theMopanshan Reservoir

the exception of site 2 3 and 11 contributions ranging from331 to 963 followed byDBP ranging from 21 to 363The results are consistent with the above data for overallanalysis that DBP and DEHP are the dominant componentsof the PAEs distribution pattern in each sampling site whichreflected the different pattern of plastic contaminant inputduring the sampling period Similarly DIBP and DBP areused in epoxy resins or special adhesive formulations withthe different proportions of these two PAE congeners whichwere also the important indicator of the information pollutedby PAEs for the sampling locations Although the limitedsample number draws only limited conclusions there is stillreason to note that a leaching from the plastic materials intothe runoff water is possible and that water runoff from thecontaminated water is a burden pathway from differentsources of PAEs [14]

33 Comparison with Other Water Bodies Comparison withthe total PAEs concentrations is nevertheless very limited dueto the different analysis compounds However the individualPAE namely DBP and DEHP is by far the most abundantin other researches and it is possible to make a camparisonwith our findings In this case the results of DBP and DEHPconcentrations published in literatures for kinds of waterbodies are presented together in Table 3

The DEHP and DBP concentrations of the present studyshowed to some extent lower concentration levels than thosereported in the other water bodies in China In comparisonthe results were comparable or similar to those from theexaminations described in other foreign countries For exam-ple as shown in Table 3 the DEHP concentrations were sim-ilar to the surface waters from the Netherlands and Italydescribed in the literature Meanwhile these concentrationsin this study were quite lower than the Yangtze River andSecond Songhua River in China

0

20

40

60

80

100

DEEP DPP DHXP DEHP DNOP DBP

DIBP DEP DMP

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

Com

posit

ion

()

Figure 5 PAE composition of thewater samples in 16 sampling sites

In conclusion as compared to the results of other studiesthe waters near the Mopanshan Reservoir were moderatelypolluted by PAEs Therefore there is a definite need to set upa properly planned and systematic approach to water controlnear the Mopanshan Reservoir

34 PAE Levels in the Waterworks The Mopanshan Water-works (MPSW) equipped essentially with the water sourceof the Mopanshan Reservoir has been investigated in orderto assess the fate of the PAEs during the drinking watertreatment process For comparison a sampling campaign forthe determination of PAEs levels in the Seven Waterworks(SW waterworks with the old water source of the SonghuaRiver) was carried out Both waterworks operate coagulationsedimentation and followed by filtration treatment processwhich are typical traditional drinking water treatment

The measured concentrations in the raw and finishedwater of the two investigated waterworks are shown inFigure 6 Six out of fifteen PAEs were detected in the fin-ished water from the two waterworks The detected PAEswere DMP DEP DIBP DBP DEHP and DNOP and theother investigated phthalates are of minor importance withconcentrations all below the limit of detection As showin Figure 6 the measured concentrations of the analyzedPAEs in the finished water of the two waterworks variedstronglyThemost important compound in the finishedwaterwas DEHP with the mean concentration of 34737 and40592 ngL for the MPSW and SW respectively suggestingthe highest relative composition of total PAE concentrationsin the drinking water

For the raw water from the different water sources DMPand DIBP concentrations in the MPSW were much lowerthan the ones in the SW and the concentrations of DEPDBP DEHP andDEHPwere relatively comparable in the two

6 Journal of Analytical Methods in Chemistry

Table 3 Comparison of the concentrations of DEHP and DBP in the water bodies (ngL)

Location DEHP DBP ReferenceRange Median Mean Range Median Mean

Surface water Germany 330ndash97800 2270 mdash 120ndash8800 500 mdash [14]Surface water the Netherlands ndndash5000 320 mdash 66ndash3100 250 mdash [15]Seine River estuary France 160ndash314 mdash mdash 67ndash319 mdash mdash [16]Tama River Japan 13ndash3600 mdash mdash 8ndash540 mdash mdash [17]Velino River Italy ndndash6400 mdash mdash ndndash44300 mdash mdash [2]Surface water Taiwan ndndash18500 mdash 9300 1000ndash13500 mdash 4900 [18]Surface water Jiangsu China 556ndash156707 mdash mdash 16ndash58575 mdash mdash [19]Yangtze River mainstream China 3900ndash54730 mdash mdash ndndash35650 mdash mdash [20]Middle and lower Yellow River China 347ndash31800 mdash mdash ndndash26000 mdash mdash [21]Second Songhua River China ndndash1752650 370020 mdash ndndash5616800 mdash 717240 [22]Urban lakes Guangzhou China 87ndash630 170 240 940ndash3600 1990 2030 [11]Xiangjiang River China 620ndash15230 mdash mdash mdash mdash mdash [23]This study 1289ndash65709 6710 17741 525ndash44982 1103 8014

0

500

1000

100001200014000

0

20

40

60

80

100

Raw waterFinished waterRemoval

Rem

oval

()

Con

cent

ratio

ns (n

gL)

DMP DEP DIBP DBP DEHP DNOP

(a)

Raw waterFinished waterRemoval

0

500

1000

1500

2000

100001200014000

0

20

40

60

80

100C

once

ntra

tions

(ng

L)

Rem

oval

()

DMP DEP DIBP DBP DEHP DNOP

(b)

Figure 6 PAEs detected in the water samples from the MPSW (a) and SW (b)

waterworks The removal of PAEs by these two waterworksranged from 258 to 765 which varied significantly with-out stable removal efficienciesThe lower removal efficienciesfor DMP and DNOP were observed in the SW with theremoval less than 30 For both the waterworks no soundremoval efficiencies were obtained for the PAEs indicatingthat the traditional drinking water treatment cannot showgood performance to eliminate these micro pollutants whichhas nothing to do with the type of the water source

Traditional drinking water treatment focuses on dealingwith the particles and colloids in terms of physical processesMany studies of the environmental fates of PAEs have demon-strated that oxidation or microbial action is the principalmechanism for their removal in the aquatic systems [24ndash26]Therefore the treatment process should be the combinationswith the key techniques for removing PAEs from the waterOn the other hand since the removal efficiencies of PAEs by

these advance drinking water treatments in waterworks hasnot been systematically studied to date further research inthis direction would seem to be required

35 Exposure Assessment of PAEs in Water To evaluate thepotential and adverse effects of PAEs quality guidelines forsurface water and drinking water standard were used Theresults indicated that the mean concentrations of DBP andDEHP at levels were well below the reference doses (RfD)regarded as unsafe by the EPA for the surface water Thelevels were not also above the RfD recommended by China(Environmental Quality Standard for SurfaceWater of ChinaGB3838-2002) On the other hand the amounts of DEHPpresent in public water supplies should be lower than thedrinkingwater standard (0006mgL for EPA and 0008mgLfor China) According to the results the concentrations of

Journal of Analytical Methods in Chemistry 7

DEHP in drinkingwater samples from theMPSWwere lowerthan the limited value

PAEs are also considered to be endocrine disruptingchemicals (EDCs) whose effects may not appear until long-term exposure According to the results PAEs were detectedin the drinking water constantly ingested in daily life indi-cating that drinking water is an important source of humanexposure to PAEs contaminants Assuming a daily waterconsumption rate of 2 L and an average body weight of 60 kgfor adults the average daily intake of DEHP DBP and DIBPby way of drinking water from MPSW was calculated to be1158 1352 and 81 ngkgd respectively In comparison thevalues of SW with the water source of the Songhua Riverwere relatively higher with the calculated results of 1353140 and 155 ngkgd for DEHP DBP and DIBP respectivelyIn this study the estimated daily intake levels of DEHPfrom the drinking water were quite lower than the RfDof 20000 ngkgd released by the EPA However some ofPAEs are partly metabolised in the organism and futureexperiments should be focused on determining the potentialeffects of the metabolites [27]

Currently treated water from the Songhua River is fornonpotable uses and MPSW is the exclusive waterworks runfor the water supply of Harbin city However populationgrowth and drought cycle are limited by the availability of rawwater from theMopanshan Reservoir Tomeet the increasingdemand local and regional water authorities have begun acampaign of second water supply project from the SonghuaRiver again which needs the protection of the Songhua Riverand advanced water treatment for the source

4 Conclusions

This study provided the first detailed data on the contami-nation status of 15 PAEs in the water near the MopanshanReservoir The concentration range of 15 PAEs in the sampleswas from 3558 to 92265 ngL with the mean value of29431 ngL DEHP andDBPwere themain pollutants among15 PAEs accounting for the main watershed pollution Theoccurrence and distribution of PAEs from different samplingsites in the water source varied largely suggesting that thespatial distribution of PAEs was site specific In additionthe monitoring of PAEs in the waterworks also showed thatPAEs can be detected in the drinking water and certaintoxicological risks to drinking water consumers were foundThese results reported here contribute to an understandingof how PAE contaminants are distributed in the new watersource and the waterworks in Harbin city as well as forminga basis for further modeling risk assessment and selection ofdrinking water treatment technology

In conclusion the results implied that no urgent reme-diation measures were required with respect to PAEs in thewaters However the ecological and health effects of thesesubstances through drinkingwater at the relatively lower con-centrations still need further notice in light of their possiblebiological magnifications Therefore the long-term sourcecontrol in the water and adding advanced treatment processfor drinking water supplies should be given special attentionin this area

Acknowledgments

This work was supported by the National Natural ScienceFoundation of China (1077029) the Funds for CreativeResearch Groups of China (Grant no 51121062) the NationalNatural Science Foundation of China (51078105) and theOpen Project of the State Key Laboratory of Urban WaterResource and Environment Harbin Institute of Technology(no QA201019)

References

[1] M Nikonorow H Mazur and H Piekacz ldquoEffect of orallyadministered plasticizers and polyvinyl chloride stabilizers inthe ratrdquo Toxicology and Applied Pharmacology vol 26 no 2 pp253ndash259 1973

[2] M Vitali M Guidotti G Macilenti and C Cremisini ldquoPhtha-late esters in freshwaters asmarkers of contamination sourcesmdasha site study in ItalyrdquoEnvironment International vol 23 no 3 pp337ndash347 1997

[3] G Latini C de Felice G Presta et al ldquoIn utero exposure todi-(2-ethylhexyl)phthalate and duration of human pregnancyrdquoEnvironmental Health Perspectives vol 111 no 14 pp 1783ndash17852003

[4] C E Mackintosh J A Maldonado M G Ikonomou and F AP C Gobas ldquoSorption of phthalate esters and PCBs in a marineecosystemrdquo Environmental Science and Technology vol 40 no11 pp 3481ndash3488 2006

[5] M Clara G Windhofer W Hartl et al ldquoOccurrence of phtha-lates in surface runoff untreated and treated wastewater andfate during wastewater treatmentrdquo Chemosphere vol 78 no 9pp 1078ndash1084 2010

[6] M M Abdel Daiem J Rivera-Utrilla R Ocampo-Perez J DMendez-Dıaz andM Sanchez-Polo ldquoEnvironmental impact ofphthalic acid esters and their removal fromwater and sedimentsby different technologiesmdasha reviewrdquo Journal of EnvironmentalManagement vol 109 pp 164ndash178 2012

[7] L Chen Y Zhao L Li B Chen and Y Zhang ldquoExposureassessment of phthalates in non-occupational populations inChinardquo Science of the Total Environment vol 427-428 pp 60ndash69 2012

[8] M J Teil M Blanchard andM Chevreuil ldquoAtmospheric fate ofphthalate esters in an urban area (Paris-France)rdquo Science of theTotal Environment vol 354 no 2-3 pp 212ndash223 2006

[9] P Roslev K Vorkamp J Aarup K Frederiksen and P HNielsen ldquoDegradation of phthalate esters in an activated sludgewastewater treatment plantrdquo Water Research vol 41 no 5 pp969ndash976 2007

[10] J Gasperi S Garnaud V Rocher and R Moilleron ldquoPrioritypollutants in wastewater and combined sewer overflowrdquo Scienceof the Total Environment vol 407 no 1 pp 263ndash272 2008

[11] F Zeng K Cui Z Xie et al ldquoOccurrence of phthalate estersin water and sediment of urban lakes in a subtropical cityGuangzhou South Chinardquo Environment International vol 34no 3 pp 372ndash380 2008

[12] F Zeng K Cui Z Xie et al ldquoPhthalate esters (PAEs) emergingorganic contaminants in agricultural soils in peri-urban areasaround Guangzhou Chinardquo Environmental Pollution vol 156no 2 pp 425ndash434 2008

[13] G Wildbrett ldquoDiffusion of phthalic acid esters from PVC milktubingrdquo Environmental Health Perspectives vol 3 pp 29ndash351973

8 Journal of Analytical Methods in Chemistry

[14] H Fromme T Kuchler T Otto K Pilz J Muller and AWenzel ldquoOccurrence of phthalates and bisphenol A and F inthe environmentrdquoWater Research vol 36 no 6 pp 1429ndash14382002

[15] A D Vethaak J Lahr S M Schrap et al ldquoAn integrated assess-ment of estrogenic contamination and biological effects in theaquatic environment ofTheNetherlandsrdquoChemosphere vol 59no 4 pp 511ndash524 2005

[16] C Dargnat M Blanchard M Chevreuil andM J Teil ldquoOccur-rence of phthalate esters in the Seine River estuary (France)rdquoHydrological Processes vol 23 no 8 pp 1192ndash1201 2009

[17] T Suzuki K Yaguchi S Suzuki and T Suga ldquoMonitoring ofphthalic acid monoesters in river water by solid-phase extrac-tion and GC-MS determinationrdquo Environmental Science andTechnology vol 35 no 18 pp 3757ndash3763 2001

[18] S Y Yuan C Liu C S Liao and B V Chang ldquoOccurrenceand microbial degradation of phthalate esters in Taiwan riversedimentsrdquo Chemosphere vol 49 no 10 pp 1295ndash1299 2002

[19] B Li C Qu and J Bi ldquoIdentification of trace organic pollutantsin drinking water and the associated human health risks inJiangsu Province Chinardquo Bulletin of Environmental Contami-nation and Toxicology pp 1ndash5 2012

[20] F Wang X Xia and Y Sha ldquoDistribution of phthalic acidesters in Wuhan section of the Yangtze River Chinardquo Journalof Hazardous Materials vol 154 no 1ndash3 pp 317ndash324 2008

[21] Y J Sha X H Xia and X Q Xiao ldquoDistribution characters ofphthalic acid ester in the waters middle and lower reaches ofthe Yellow Riverrdquo China Environmental Science vol 26 no 1pp 120ndash124 2006

[22] J Lu L-B Hao C-Z Wang W Li R-J Bai and D YanldquoDistribution characteristics of phthalic acid esters in middleand lower reaches of no 2 Songhua Riverrdquo EnvironmentalScience amp Technology vol 12 article 014 2007

[23] X J Zhu and Y Y Qiu ldquoMeasuring the phthalates of xiangjiangriver using liquid-liquid extraction gas chromatographyrdquoAdvanced Materials Research vol 301 pp 752ndash755 2011

[24] B L Yuan X Z Li and N Graham ldquoAqueous oxida-tion of dimethyl phthalate in a Fe(VI)-TiO

2

-UV reaction sys-temrdquoWater Research vol 42 no 6-7 pp 1413ndash1420 2008

[25] Z Yunrui ZWanpeng L FudongW Jianbing and Y ShaoxialdquoCatalytic activity of RuAl2O3 for ozonation of dimethylphthalate in aqueous solutionrdquo Chemosphere vol 66 no 1 pp145ndash150 2007

[26] H N Gavala U Yenal and B K Ahring ldquoThermal andenzymatic pretreatment of sludge containing phthalate estersprior tomesophilic anaerobic digestionrdquoBiotechnology and Bio-engineering vol 85 no 5 pp 561ndash567 2004

[27] Y Guo Q Wu and K Kannan ldquoPhthalate metabolites in urinefrom China and implications for human exposuresrdquo Environ-ment International vol 37 no 5 pp 893ndash898 2011

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 210653 8 pageshttpdxdoiorg1011552013210653

Research ArticleSimultaneous Determination of Hormonal Residuesin Treated Waters Using Ultrahigh Performance LiquidChromatography-Tandem Mass Spectrometry

Rayco Guedes-Alonso Zoraida Sosa-Ferrera and Joseacute Juan Santana-Rodriacuteguez

Departamento de Quımica Universidad de Las Palmas de Gran Canaria 35017 Las Palmas de Gran Canaria Spain

Correspondence should be addressed to Jose Juan Santana-Rodrıguez jsantanadquiulpgces

Received 28 December 2012 Accepted 7 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Rayco Guedes-Alonso et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

In the last years hormone consumption has increased exponentially Because of that hormone compounds are considered emergingpollutants since several studies have determinted their presence in water influents and effluents of wastewater treatment plants(WWTPs) In this study a quantitative method for the simultaneous determination of oestrogens (estrone 17120573-estradiol estriol17120572-ethinylestradiol and diethylstilbestrol) androgens (testosterone) and progestogens (norgestrel andmegestrol acetate) has beendeveloped to determine these compounds in wastewater samples Due to the very low concentrations of target compounds in theenvironment a solid phase extraction procedure has been optimized and developed to extract and preconcentrate the analytesDetermination and quantification were performed by ultrahigh performance liquid chromatography-tandem mass spectrometry(UHPLC-MSMS) The method developed presents satisfactory limits of detection (between 015 and 935 ngsdotLminus1) good recoveries(between 73 and 90 for the most of compounds) and low relative standard deviations (under 84) Samples from influents andeffluents of two wastewater treatment plants of Gran Canaria (Spain) were analyzed using the proposed method finding severalhormones with concentrations ranged from 5 to 300 ngsdotLminus1

1 Introduction

In general it is supposed that more than 100000 differentchemical compounds can be introduced in the Environmentmany of them in very small quantity However a lot of thesecompounds are not included as pollutants in the legislationAlthough these compounds named emerging pollutants arenot regulated as pollutants they probably will be in the futurebecause of their potential negative effect in the ecosystem For20 years many articles have reported the presence of theseldquonew compoundsrdquo in wastewater [1 2]

The emerging pollutant origin is mainly anthropogenicconsidering that the majority of these compounds are bio-logically active substances that are synthesized to use themin agriculture industry and medicine The main source ofthese emerging pollutants is the residual urbanwaters and thewastewater treatment plants effluents because many of these

WWTPs are not designed or optimized to treat this kind ofcompounds [3]

Hormones are one of the most potent endocrine disrupt-ing compounds as well as are considered also as emergingpollutants Hormones can be differentiated in oestrogensandrogens and progestogens Some of them have limits intheir use but not a specific legislation [4]

The main characteristic of these pollutants is that it isnot necessary to remain in the environment to cause negativeeffects in view of the fact that their constant introduction init offsets their removal or degradation [5]

The steroid hormones help controlling the metabolisminflammations immunological functions water and salt bal-ance sexual development and the capacity of withstandingillnesses [6] The term steroid can be used for naturalhormones produced by the body as well as for artificiallyproduced medicines that increase the natural steroid effect

2 Journal of Analytical Methods in Chemistry

In the last 50 years the natural and synthetic hormoneworldwide consumption has grown as much as in humanmedicine as in cattle farming and they become the mostprescribed medicines [7]

A significant quantity of consumed oestrogens leaves theorganism through excretions For example 17120573-estradiol (E2)is oxidized rapidly becoming an estrone (E1) that can turninto estriol afterwards (E3) Besides the 17120572-ethinyl estradiol(EE) is excreted as conjugated [8]

With regard to emission sources in the first place arethe wastewater treatment plants (WWTPs) [9] and secon-darily cattle waste such as those leachates from dung anduncontrolled dumping [10] Several studies made in theWWTPs have reported that the treatment plants are capableof eliminating around 60 of hormones [11ndash13]

The identification of hormone residues in environmentis of special interest because knowledge of these compoundsis a requirement to take measures in order to regulate andminimize their environmental impact

However measurement of hormone residues is a verydifficult task not only due to the difficulty in measuringvery low concentration but also due to a very complexityof the samples Therefore use of mass spectrometer (MS)as detector coupled with chromatography techniques hasbecome a powerful method for the analysis of these typesof compounds at trace levels [14ndash17] Consequently LC-MSMS is the principally chosen technique One of the mainadvantages of LC-MSMS is its ability to analyze hormoneswithout derivatization (necessary in GC) or the need ofhydrolyze the conjugated form

Due to low level concentration of these compounds inenvironmental water it is necessary to apply an extractionand preconcentration method prior to LC analysis The mostused technique of extraction and preconcentration methodfor liquid samples is the solid phase extraction (SPE) [18ndash20]

The objective of this study is to develop a rapid and simpleprocedure of extraction preconcentration and determina-tion of four steroid oestrogens (estrone (E1) 17120573-estradiol(E2) estriol (E3) and 17120572-ethinylestradiol (EE)) one non-steroidal oestrogen the diethylstilbestrol (DES) one andro-gen the testosterone (TES) and two synthetic progestogensnorgestrel (NOR) and megestrol acetate (MGA) (Table 1)based on solid phase extraction and ultrahigh performanceliquid chromatography-tandem mass spectrometry (SPE-UHPLC-MSMS) The developed method was applied tothe identification and quantification of these compoundsin wastewater samples obtained from the influents andeffluents of two wastewater treatment plants (WWTPs) ofGran Canaria (Spain) They presented different methodsof wastewater treatments WWTP 1 presented a traditionalmethod based on activated sludge while WWTP 2 used amembrane bioreactor technique

2 Materials and Methods

21 Reagents All of the hormonal compounds usedwere pur-chased from Sigma-Aldrich (Madrid Spain) Stock solutionscontaining 1000mgsdotLminus1 of each analyte were prepared by

dissolving the compound inmethanol and the solutionswerestored in glass-stoppered bottles at 4∘C prior to use Workingaqueous standard solutions were prepared daily Ultrapurewater was provided by a Milli-Q system (Millipore BedfordMA USA) HPLC-grade methanol LC-MS methanol andLC-MS water as well as the ammonia and the ammoniumacetate used to adjust the pH of the mobile phases wereobtained from Panreac Quımica (Barcelona Spain)

22 Sample Collection Water samples were collected fromthe effluents of twowastewater treatment plants located in thenorthern area of Gran Canaria in May and August of 2012WWTP 1 used a conventional activated sludge treatmentsystem while WWTP 2 employed a membrane bioreactortreatment system The samples were collected in 2 L amberglass bottles that were rinsed beforehand with methanol andultrapurewater Samples were purified through filtrationwithfibreglass filters and then with 065 120583m membrane filters(Millipore Ireland) The samples were stored in the dark at4∘C and extracted within 48 hours

23 Instrumentation For the SPE optimization the instru-ment used was an ultrahigh performance liquid chromatog-raphy with fluorescence detector (UHPLC-FD) system con-sisting of an ACQUITYQuaternary Solvent Manager (QSM)used to load samples and wash and recondition the analyticalcolumn an autosampler a column manager and a fluores-cence detector with excitation and emission wavelengths of280 and 310 nm respectively all fromWaters (Madrid Spain)

The analysis of wastewater samples was performed ina UHPLC-MSMS system from Waters (Madrid Spain)similar to the described above with a 2777 autosamplerequipped with a 25120583L syringe and a tray to hold 2mLvials and an ACQUITY tandem triple quadrupole (TQD)mass spectrometer with an electrospray ionization (ESI)interface All Waters components (Madrid Spain) werecontrolled using the MassLynx Mass Spectrometry SoftwareElectrospray ionisation parameters were fixed as followsthe capillary voltage was 3 kV in positive mode and minus2 kVin negative mode the source temperature was 150∘C thedesolvation temperature was 500∘C and the desolvation gasflow rate was 1000 Lhr Nitrogen was used as the desolvationgas and argon was employed as the collision gas

The detailed MSMS detection parameters for each hor-monal compound are presented in Table 2 and were opti-mised by the direct injection of a 1mgsdotLminus1 standard solutionof each analyte into the detector at a flow rate of 10 120583Lsdotminminus1

24 Chromatographic Conditions For the SPE optimizationthe analytical column was a 50mm times 21mm ACQUITYUHPLCBEHWaters C

18columnwith a particle size of 17120583m

(Waters Chromatography Barcelona Spain) operating at atemperature of 30∘C Analytes separation was carried outemploying the following gradient starting at 55 45 (vv)water methanol for 1 minute During 3 minutes it changedto 50 50 (vv) and stayed for 25 minutes more Finally cameback to initial conditions in 1 minute and stayed for 15

Journal of Analytical Methods in Chemistry 3

Table 1 List of hormonal compounds pKa values chemical structure and retention times

Compound pKa [21] Structure 119905119877

(min)

E3 Estriol 103

HO

OH

OH

H H

H096

E2 17120573-estradiol 103

HO

OH

H H

H218

EE 17120572-ethinylestradiol 103

HO

HO

H H

H223

E1 Estrone 103

HO

O

H

H H220

DES Diethylstilbestrol 102

HO

OH

235

TES Testosterone 151

OH

OH H

H240

MGA Megestrol acetate

O

O

O

OH

H

H306

NOR Levonorgestrel 131

OH

O

H

H

H

H263

minutes Therefore the analysis took 9 minutes at a flow of05mLsdotminminus1

For the analysis of real samples aUHPLC-MSMS systemwas used The analytical column was the same and themobile phase was water and methanol adjusted with a bufferconsisting in 01 vv ammonia and 15mM of ammoniumacetate The analysis was performed in gradient mode at aflow rate of 03mLsdotminminus1The gradient started at 50 50 (vv)mixture of water methanol which changed to 25 75 (vv) in3 minutes and returned to 50 50 in 1 minute more Finallythe gradient stayed calibrating for another 15 minutes moreThe sample volume injected was 5120583L

3 Results and Discussion

31 Optimization of Solid-Phase Extraction (SPE) There area number of parameters that affect SPE procedure such as

type of sorbent pH ionic strength sample and desorptionvolumes and wash step To optimize these parameters itused Milli-Q water spiked with a solution of fluorescenceoestrogens (estriol 17120573-estradiol and 17120572-ethinylestradiol)to obtain a final concentration of 250120583gsdotLminus1

The first parameter to optimize is the choice of sorbentsince it controls the selectivity affinity and capacity overanalytes In this study the SPE cartridges used were OASISHLB SepPak C

18(both from Waters Madrid Spain) and

BondElut ENV (fromAgilent Madrid Spain) Keeping otherparameters fixed (ionic strength of 0 sample volume of100mL) the cartridges were studied at three different pHs(5 8 and 11) From the results obtained it can be observedthat the better signals are found for SepPak C

18cartridge

(Figure 1)After choosing the optimum cartridge we used an initial

experimental design of 23 to study the influence of pH ionic

4 Journal of Analytical Methods in Chemistry

Table 2 Mass spectrometer parameters for the determination of target analytes

Compound Precursor ion(mz)

Capillary voltage(Ion mode)

Quantification ionmz(collision potential V)

Quantification ionmz(collision potential V)

E3 2872 minus65V (ESI minus) 1710 (37) 1452 (39)E2 2712 minus65V (ESI minus) 1451 (40) 1831 (31)EE 2952 minus60V (ESI minus) 1450 (37) 1589 (33)E1 2692 minus65V (ESI minus) 1450 (36) 1430 (48)DES 2671 minus50V (ESI minus) 2371 (29) 2511 (25)TES 2892 38V (ESI +) 1870 (18) 1040 (21)MGA 3855 30V (ESI +) 2673 (15) 2242 (30)NOR 3132 38V (ESI +) 1090 (26) 2451 (18)

0

500

1000

1500

2000

2500

E3 E2 EE

Peak

area

Cartridge optimizationOASIS HLB pH = 5

OASIS HLB pH = 8

OASIS HLB pH = 11SepPak C18 pH = 5

SepPak C18 pH = 8

SepPak C18 pH = 11BondElut ENV pH = 5

BondElut ENV pH = 8

BondElut ENV pH =11

Figure 1 Optimization of SPE cartridges

strength and sample volume over extraction process Theexperimental design was obtained using Statgraphics Plussoftware 51 and the statistics study was done with IBM SPSSStatistics 19 We assessed two levels and three parameters pH(3 and 8) ionic strength (0 and 30 of NaCl) and samplevolume (50 and 250mL) to obtain the influence of eachparameter and the variable correlation to each other In thisstudy it is observed that the ionic strength and sample volumehad the major influence on the recoveries of the analytesFor that a 32 factorial design to optimize these two variablesat three levels per parameter (0 15 and 30 of NaCl forionic strength and 50 100 y 250mL for sample volume) wasused Figure 2 shows the response surface obtained for theestriol and 17120572-ethinylestradiol The results obtained showedthat an increment of the ionic strength did not producean increase in the response area of the compound and theoptimum volume was 250mL Because of that a solutionwithout salt addition and 250mL of sample volume waschosen Finally the desorption volume (1mLofmethanol and2mL of methanol in one and two steps) and wash-step (5mL

ofMilli-Q water and 5mL ofMilli-Q water with 5 and 10 ofmethanol vv) were assayed to complete the optimization ofthe SPE process The optimum values were 2mL of methanolin one step and 5mL of Milli-Q water without methanolrespectively

In accordance with the obtained results the optimumconditions for SPE procedure were SepPak C

18cartridge

250mL of sample at pH = 8 and 0 of NaCl desorptionwith 2mL of methanol in one step and wash step with5mL of Milli-Q water In these conditions we achieved apreconcentration factor of 125 In Figure 3 a chromatogramwith the optimum conditions is shown where the peaksof all compounds in their corresponding transitions can beobserved

32 Analytical Parameters Because of the SPE optimizationthat was done only with fluorescent compounds (estriol 17120573-estradiol and 17120572-ethinylestradiol) it was necessary to studythe recoveries of all the hormonal compounds using theoptimized SPE-UHPLC-MSMSmethod All the compoundsunder study showed good recoveries over 73 except thediethylstilbestrol with a recovery of 507

A calibration curve was used for the quantification ofthe analytes by diluting the stock solution of each analyteinto the samples to concentrations ranging between 1 and100 120583gsdotLminus1 Analysis was conducted by UHPLC-MSMS andlinear calibration plots for each analyte (1199032 gt 099) wereobtained based on their chromatographic peak areas

The limit of detection (LOD) and the limit of quantifi-cation (LOQ) for each compound were calculated from thesignal-to-noise ratio of each individual peak The LOD wasdefined as the lowest concentration that gave a signal-to-noiseratio that was greater than 3 The LOQ was defined as thelowest concentration that gave a signal to noise ratio that wasgreater than 10The LODs ranged from015 to 935 ngsdotLminus1 andthe LOQs ranged from 049 to 3118 ngsdotLminus1

The performance and reliability of the process werestudied by determining the repeatability of the quantificationresults for all target analytes under the described conditionsusing six samples (119899 = 6) The relative standard deviations(RSDs) were lower than 84 in all cases indicating a

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 11: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

4 Journal of Analytical Methods in Chemistry

0 2000 4000 6000 80000

2000

4000

6000

Con

cent

ratio

ns (n

gL)

DEHP

119903 = 0885 119875 lt 001

sum15PAEs (ngL)

(a)

0 2000 4000 6000 80000

2000

4000

Con

cent

ratio

ns (n

gL)

sum15PAEs (ngL)

DBP

119903 = 0812 119875 lt 001

(b)

1000

500

0

0 2000 4000 6000 8000sum15PAEs (ngL)

DIBP

Con

cent

ratio

ns (n

gL)

119903 = 0724 119875 lt 001

(c)

Figure 3 Correlations of the concentration of the major PAEs (DEHP DBP and DIBP) with the concentrations of total PAEs in the watersamples

Table 2 Concentrations of 15 PAEs in water samples near the Mopanshan Reservoir

PAEs Abbreviation Water (ngL)Range Mean Frequency

Dimethyl phthalate DMP ndndash424 140 816Diethyl phthalate DEP ndndash550 284 1516Diisobutyl phthalate DIBP 400ndash6588 1966 1616Dibutyl phthalate DBP 525ndash44982 8014 1616bis(2-methoxyethyl)phthalate DMEP nd nd 016bis(4-methyl-2-pentyl)phthalate BMPP nd nd 016bis(2-ethoxyethyl)phthalate DEEP ndndash546 128 516Dipentyl phthalate DPP ndndash925 455 1016Dihexyl phthalate DHXP ndndash651 162 516Benzyl butyl phthalate BBP nd nd 016bis(2-n-butoxyethyl)phthalate DBEP nd nd 016Dicyclohexyl phthalate DCHP nd nd 016bis(2-ethylhexyl)phthalate DEHP 1289ndash65709 17741 1616Di-n-octyl phthalate DNOP ndndash4482 541 516Dinonyl phthalate DNP nd nd 016sum15

PAEs 3558ndash92265 29431 mdash

The distribution of 15 PAEs (sum15

PAEs) studied and6 US EPA priority PAEs (sum

6

PAEs including DMP DEPDIBP DBP DEHP and DNOP) in the waters from differentsampling sites are shown in Figure 4 There was an obviousvariation in the total sum

15

PAEs concentrations in water sam-ples near the Mopanshan Reservoir the concentrations ofsum6

PAEs from the same sampling sites varied from 2690 to90860 ngL with an average of 28686 ngL the distributionspectra of which observed for all the sampling sites weresimilar tosum

15

PAEsThe highest levels of PAEs contaminationwere seen on the sampling site 3 followed by some relativelyheavily polluted sites (site 16 13 9 10 and 11) indicating thatthese sites served as important PAE sources and the spatialdistribution of PAEs was site specific The levels in the watersexamined varied over a wide range especially in theMangniu

River near theMopanshan Reservoir (in some case overmorethan one order of magnitude) In general it should be notedthat there might be a relation of PAEs levels with the input oflocal waste such as sewage water food packaging and scrapmaterial near the sampling point which were found duringthe sampling period

32 PAE Congener Profiles in the Water Different PAE pat-terns may indicate different sources of PAEs Measurementof the individual PAE composition is helpful to track thecontaminant source and demonstrate the transport and fateof these compounds in water [11] The relative contributionsof the 9 detectable PAE congeners to thesum

15

PAEs concentra-tions in the water are presented in Figure 5 It is clear thatDEHP was the most abundant in the water samples with

Journal of Analytical Methods in Chemistry 5

0

500

1000

1500

4000

6000

8000

10000

Con

cent

ratio

ns (n

gL)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

sum15PAEssum6PAEs

Figure 4 Spatial distributions of the 16 sampling sites near theMopanshan Reservoir

the exception of site 2 3 and 11 contributions ranging from331 to 963 followed byDBP ranging from 21 to 363The results are consistent with the above data for overallanalysis that DBP and DEHP are the dominant componentsof the PAEs distribution pattern in each sampling site whichreflected the different pattern of plastic contaminant inputduring the sampling period Similarly DIBP and DBP areused in epoxy resins or special adhesive formulations withthe different proportions of these two PAE congeners whichwere also the important indicator of the information pollutedby PAEs for the sampling locations Although the limitedsample number draws only limited conclusions there is stillreason to note that a leaching from the plastic materials intothe runoff water is possible and that water runoff from thecontaminated water is a burden pathway from differentsources of PAEs [14]

33 Comparison with Other Water Bodies Comparison withthe total PAEs concentrations is nevertheless very limited dueto the different analysis compounds However the individualPAE namely DBP and DEHP is by far the most abundantin other researches and it is possible to make a camparisonwith our findings In this case the results of DBP and DEHPconcentrations published in literatures for kinds of waterbodies are presented together in Table 3

The DEHP and DBP concentrations of the present studyshowed to some extent lower concentration levels than thosereported in the other water bodies in China In comparisonthe results were comparable or similar to those from theexaminations described in other foreign countries For exam-ple as shown in Table 3 the DEHP concentrations were sim-ilar to the surface waters from the Netherlands and Italydescribed in the literature Meanwhile these concentrationsin this study were quite lower than the Yangtze River andSecond Songhua River in China

0

20

40

60

80

100

DEEP DPP DHXP DEHP DNOP DBP

DIBP DEP DMP

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

Com

posit

ion

()

Figure 5 PAE composition of thewater samples in 16 sampling sites

In conclusion as compared to the results of other studiesthe waters near the Mopanshan Reservoir were moderatelypolluted by PAEs Therefore there is a definite need to set upa properly planned and systematic approach to water controlnear the Mopanshan Reservoir

34 PAE Levels in the Waterworks The Mopanshan Water-works (MPSW) equipped essentially with the water sourceof the Mopanshan Reservoir has been investigated in orderto assess the fate of the PAEs during the drinking watertreatment process For comparison a sampling campaign forthe determination of PAEs levels in the Seven Waterworks(SW waterworks with the old water source of the SonghuaRiver) was carried out Both waterworks operate coagulationsedimentation and followed by filtration treatment processwhich are typical traditional drinking water treatment

The measured concentrations in the raw and finishedwater of the two investigated waterworks are shown inFigure 6 Six out of fifteen PAEs were detected in the fin-ished water from the two waterworks The detected PAEswere DMP DEP DIBP DBP DEHP and DNOP and theother investigated phthalates are of minor importance withconcentrations all below the limit of detection As showin Figure 6 the measured concentrations of the analyzedPAEs in the finished water of the two waterworks variedstronglyThemost important compound in the finishedwaterwas DEHP with the mean concentration of 34737 and40592 ngL for the MPSW and SW respectively suggestingthe highest relative composition of total PAE concentrationsin the drinking water

For the raw water from the different water sources DMPand DIBP concentrations in the MPSW were much lowerthan the ones in the SW and the concentrations of DEPDBP DEHP andDEHPwere relatively comparable in the two

6 Journal of Analytical Methods in Chemistry

Table 3 Comparison of the concentrations of DEHP and DBP in the water bodies (ngL)

Location DEHP DBP ReferenceRange Median Mean Range Median Mean

Surface water Germany 330ndash97800 2270 mdash 120ndash8800 500 mdash [14]Surface water the Netherlands ndndash5000 320 mdash 66ndash3100 250 mdash [15]Seine River estuary France 160ndash314 mdash mdash 67ndash319 mdash mdash [16]Tama River Japan 13ndash3600 mdash mdash 8ndash540 mdash mdash [17]Velino River Italy ndndash6400 mdash mdash ndndash44300 mdash mdash [2]Surface water Taiwan ndndash18500 mdash 9300 1000ndash13500 mdash 4900 [18]Surface water Jiangsu China 556ndash156707 mdash mdash 16ndash58575 mdash mdash [19]Yangtze River mainstream China 3900ndash54730 mdash mdash ndndash35650 mdash mdash [20]Middle and lower Yellow River China 347ndash31800 mdash mdash ndndash26000 mdash mdash [21]Second Songhua River China ndndash1752650 370020 mdash ndndash5616800 mdash 717240 [22]Urban lakes Guangzhou China 87ndash630 170 240 940ndash3600 1990 2030 [11]Xiangjiang River China 620ndash15230 mdash mdash mdash mdash mdash [23]This study 1289ndash65709 6710 17741 525ndash44982 1103 8014

0

500

1000

100001200014000

0

20

40

60

80

100

Raw waterFinished waterRemoval

Rem

oval

()

Con

cent

ratio

ns (n

gL)

DMP DEP DIBP DBP DEHP DNOP

(a)

Raw waterFinished waterRemoval

0

500

1000

1500

2000

100001200014000

0

20

40

60

80

100C

once

ntra

tions

(ng

L)

Rem

oval

()

DMP DEP DIBP DBP DEHP DNOP

(b)

Figure 6 PAEs detected in the water samples from the MPSW (a) and SW (b)

waterworks The removal of PAEs by these two waterworksranged from 258 to 765 which varied significantly with-out stable removal efficienciesThe lower removal efficienciesfor DMP and DNOP were observed in the SW with theremoval less than 30 For both the waterworks no soundremoval efficiencies were obtained for the PAEs indicatingthat the traditional drinking water treatment cannot showgood performance to eliminate these micro pollutants whichhas nothing to do with the type of the water source

Traditional drinking water treatment focuses on dealingwith the particles and colloids in terms of physical processesMany studies of the environmental fates of PAEs have demon-strated that oxidation or microbial action is the principalmechanism for their removal in the aquatic systems [24ndash26]Therefore the treatment process should be the combinationswith the key techniques for removing PAEs from the waterOn the other hand since the removal efficiencies of PAEs by

these advance drinking water treatments in waterworks hasnot been systematically studied to date further research inthis direction would seem to be required

35 Exposure Assessment of PAEs in Water To evaluate thepotential and adverse effects of PAEs quality guidelines forsurface water and drinking water standard were used Theresults indicated that the mean concentrations of DBP andDEHP at levels were well below the reference doses (RfD)regarded as unsafe by the EPA for the surface water Thelevels were not also above the RfD recommended by China(Environmental Quality Standard for SurfaceWater of ChinaGB3838-2002) On the other hand the amounts of DEHPpresent in public water supplies should be lower than thedrinkingwater standard (0006mgL for EPA and 0008mgLfor China) According to the results the concentrations of

Journal of Analytical Methods in Chemistry 7

DEHP in drinkingwater samples from theMPSWwere lowerthan the limited value

PAEs are also considered to be endocrine disruptingchemicals (EDCs) whose effects may not appear until long-term exposure According to the results PAEs were detectedin the drinking water constantly ingested in daily life indi-cating that drinking water is an important source of humanexposure to PAEs contaminants Assuming a daily waterconsumption rate of 2 L and an average body weight of 60 kgfor adults the average daily intake of DEHP DBP and DIBPby way of drinking water from MPSW was calculated to be1158 1352 and 81 ngkgd respectively In comparison thevalues of SW with the water source of the Songhua Riverwere relatively higher with the calculated results of 1353140 and 155 ngkgd for DEHP DBP and DIBP respectivelyIn this study the estimated daily intake levels of DEHPfrom the drinking water were quite lower than the RfDof 20000 ngkgd released by the EPA However some ofPAEs are partly metabolised in the organism and futureexperiments should be focused on determining the potentialeffects of the metabolites [27]

Currently treated water from the Songhua River is fornonpotable uses and MPSW is the exclusive waterworks runfor the water supply of Harbin city However populationgrowth and drought cycle are limited by the availability of rawwater from theMopanshan Reservoir Tomeet the increasingdemand local and regional water authorities have begun acampaign of second water supply project from the SonghuaRiver again which needs the protection of the Songhua Riverand advanced water treatment for the source

4 Conclusions

This study provided the first detailed data on the contami-nation status of 15 PAEs in the water near the MopanshanReservoir The concentration range of 15 PAEs in the sampleswas from 3558 to 92265 ngL with the mean value of29431 ngL DEHP andDBPwere themain pollutants among15 PAEs accounting for the main watershed pollution Theoccurrence and distribution of PAEs from different samplingsites in the water source varied largely suggesting that thespatial distribution of PAEs was site specific In additionthe monitoring of PAEs in the waterworks also showed thatPAEs can be detected in the drinking water and certaintoxicological risks to drinking water consumers were foundThese results reported here contribute to an understandingof how PAE contaminants are distributed in the new watersource and the waterworks in Harbin city as well as forminga basis for further modeling risk assessment and selection ofdrinking water treatment technology

In conclusion the results implied that no urgent reme-diation measures were required with respect to PAEs in thewaters However the ecological and health effects of thesesubstances through drinkingwater at the relatively lower con-centrations still need further notice in light of their possiblebiological magnifications Therefore the long-term sourcecontrol in the water and adding advanced treatment processfor drinking water supplies should be given special attentionin this area

Acknowledgments

This work was supported by the National Natural ScienceFoundation of China (1077029) the Funds for CreativeResearch Groups of China (Grant no 51121062) the NationalNatural Science Foundation of China (51078105) and theOpen Project of the State Key Laboratory of Urban WaterResource and Environment Harbin Institute of Technology(no QA201019)

References

[1] M Nikonorow H Mazur and H Piekacz ldquoEffect of orallyadministered plasticizers and polyvinyl chloride stabilizers inthe ratrdquo Toxicology and Applied Pharmacology vol 26 no 2 pp253ndash259 1973

[2] M Vitali M Guidotti G Macilenti and C Cremisini ldquoPhtha-late esters in freshwaters asmarkers of contamination sourcesmdasha site study in ItalyrdquoEnvironment International vol 23 no 3 pp337ndash347 1997

[3] G Latini C de Felice G Presta et al ldquoIn utero exposure todi-(2-ethylhexyl)phthalate and duration of human pregnancyrdquoEnvironmental Health Perspectives vol 111 no 14 pp 1783ndash17852003

[4] C E Mackintosh J A Maldonado M G Ikonomou and F AP C Gobas ldquoSorption of phthalate esters and PCBs in a marineecosystemrdquo Environmental Science and Technology vol 40 no11 pp 3481ndash3488 2006

[5] M Clara G Windhofer W Hartl et al ldquoOccurrence of phtha-lates in surface runoff untreated and treated wastewater andfate during wastewater treatmentrdquo Chemosphere vol 78 no 9pp 1078ndash1084 2010

[6] M M Abdel Daiem J Rivera-Utrilla R Ocampo-Perez J DMendez-Dıaz andM Sanchez-Polo ldquoEnvironmental impact ofphthalic acid esters and their removal fromwater and sedimentsby different technologiesmdasha reviewrdquo Journal of EnvironmentalManagement vol 109 pp 164ndash178 2012

[7] L Chen Y Zhao L Li B Chen and Y Zhang ldquoExposureassessment of phthalates in non-occupational populations inChinardquo Science of the Total Environment vol 427-428 pp 60ndash69 2012

[8] M J Teil M Blanchard andM Chevreuil ldquoAtmospheric fate ofphthalate esters in an urban area (Paris-France)rdquo Science of theTotal Environment vol 354 no 2-3 pp 212ndash223 2006

[9] P Roslev K Vorkamp J Aarup K Frederiksen and P HNielsen ldquoDegradation of phthalate esters in an activated sludgewastewater treatment plantrdquo Water Research vol 41 no 5 pp969ndash976 2007

[10] J Gasperi S Garnaud V Rocher and R Moilleron ldquoPrioritypollutants in wastewater and combined sewer overflowrdquo Scienceof the Total Environment vol 407 no 1 pp 263ndash272 2008

[11] F Zeng K Cui Z Xie et al ldquoOccurrence of phthalate estersin water and sediment of urban lakes in a subtropical cityGuangzhou South Chinardquo Environment International vol 34no 3 pp 372ndash380 2008

[12] F Zeng K Cui Z Xie et al ldquoPhthalate esters (PAEs) emergingorganic contaminants in agricultural soils in peri-urban areasaround Guangzhou Chinardquo Environmental Pollution vol 156no 2 pp 425ndash434 2008

[13] G Wildbrett ldquoDiffusion of phthalic acid esters from PVC milktubingrdquo Environmental Health Perspectives vol 3 pp 29ndash351973

8 Journal of Analytical Methods in Chemistry

[14] H Fromme T Kuchler T Otto K Pilz J Muller and AWenzel ldquoOccurrence of phthalates and bisphenol A and F inthe environmentrdquoWater Research vol 36 no 6 pp 1429ndash14382002

[15] A D Vethaak J Lahr S M Schrap et al ldquoAn integrated assess-ment of estrogenic contamination and biological effects in theaquatic environment ofTheNetherlandsrdquoChemosphere vol 59no 4 pp 511ndash524 2005

[16] C Dargnat M Blanchard M Chevreuil andM J Teil ldquoOccur-rence of phthalate esters in the Seine River estuary (France)rdquoHydrological Processes vol 23 no 8 pp 1192ndash1201 2009

[17] T Suzuki K Yaguchi S Suzuki and T Suga ldquoMonitoring ofphthalic acid monoesters in river water by solid-phase extrac-tion and GC-MS determinationrdquo Environmental Science andTechnology vol 35 no 18 pp 3757ndash3763 2001

[18] S Y Yuan C Liu C S Liao and B V Chang ldquoOccurrenceand microbial degradation of phthalate esters in Taiwan riversedimentsrdquo Chemosphere vol 49 no 10 pp 1295ndash1299 2002

[19] B Li C Qu and J Bi ldquoIdentification of trace organic pollutantsin drinking water and the associated human health risks inJiangsu Province Chinardquo Bulletin of Environmental Contami-nation and Toxicology pp 1ndash5 2012

[20] F Wang X Xia and Y Sha ldquoDistribution of phthalic acidesters in Wuhan section of the Yangtze River Chinardquo Journalof Hazardous Materials vol 154 no 1ndash3 pp 317ndash324 2008

[21] Y J Sha X H Xia and X Q Xiao ldquoDistribution characters ofphthalic acid ester in the waters middle and lower reaches ofthe Yellow Riverrdquo China Environmental Science vol 26 no 1pp 120ndash124 2006

[22] J Lu L-B Hao C-Z Wang W Li R-J Bai and D YanldquoDistribution characteristics of phthalic acid esters in middleand lower reaches of no 2 Songhua Riverrdquo EnvironmentalScience amp Technology vol 12 article 014 2007

[23] X J Zhu and Y Y Qiu ldquoMeasuring the phthalates of xiangjiangriver using liquid-liquid extraction gas chromatographyrdquoAdvanced Materials Research vol 301 pp 752ndash755 2011

[24] B L Yuan X Z Li and N Graham ldquoAqueous oxida-tion of dimethyl phthalate in a Fe(VI)-TiO

2

-UV reaction sys-temrdquoWater Research vol 42 no 6-7 pp 1413ndash1420 2008

[25] Z Yunrui ZWanpeng L FudongW Jianbing and Y ShaoxialdquoCatalytic activity of RuAl2O3 for ozonation of dimethylphthalate in aqueous solutionrdquo Chemosphere vol 66 no 1 pp145ndash150 2007

[26] H N Gavala U Yenal and B K Ahring ldquoThermal andenzymatic pretreatment of sludge containing phthalate estersprior tomesophilic anaerobic digestionrdquoBiotechnology and Bio-engineering vol 85 no 5 pp 561ndash567 2004

[27] Y Guo Q Wu and K Kannan ldquoPhthalate metabolites in urinefrom China and implications for human exposuresrdquo Environ-ment International vol 37 no 5 pp 893ndash898 2011

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 210653 8 pageshttpdxdoiorg1011552013210653

Research ArticleSimultaneous Determination of Hormonal Residuesin Treated Waters Using Ultrahigh Performance LiquidChromatography-Tandem Mass Spectrometry

Rayco Guedes-Alonso Zoraida Sosa-Ferrera and Joseacute Juan Santana-Rodriacuteguez

Departamento de Quımica Universidad de Las Palmas de Gran Canaria 35017 Las Palmas de Gran Canaria Spain

Correspondence should be addressed to Jose Juan Santana-Rodrıguez jsantanadquiulpgces

Received 28 December 2012 Accepted 7 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Rayco Guedes-Alonso et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

In the last years hormone consumption has increased exponentially Because of that hormone compounds are considered emergingpollutants since several studies have determinted their presence in water influents and effluents of wastewater treatment plants(WWTPs) In this study a quantitative method for the simultaneous determination of oestrogens (estrone 17120573-estradiol estriol17120572-ethinylestradiol and diethylstilbestrol) androgens (testosterone) and progestogens (norgestrel andmegestrol acetate) has beendeveloped to determine these compounds in wastewater samples Due to the very low concentrations of target compounds in theenvironment a solid phase extraction procedure has been optimized and developed to extract and preconcentrate the analytesDetermination and quantification were performed by ultrahigh performance liquid chromatography-tandem mass spectrometry(UHPLC-MSMS) The method developed presents satisfactory limits of detection (between 015 and 935 ngsdotLminus1) good recoveries(between 73 and 90 for the most of compounds) and low relative standard deviations (under 84) Samples from influents andeffluents of two wastewater treatment plants of Gran Canaria (Spain) were analyzed using the proposed method finding severalhormones with concentrations ranged from 5 to 300 ngsdotLminus1

1 Introduction

In general it is supposed that more than 100000 differentchemical compounds can be introduced in the Environmentmany of them in very small quantity However a lot of thesecompounds are not included as pollutants in the legislationAlthough these compounds named emerging pollutants arenot regulated as pollutants they probably will be in the futurebecause of their potential negative effect in the ecosystem For20 years many articles have reported the presence of theseldquonew compoundsrdquo in wastewater [1 2]

The emerging pollutant origin is mainly anthropogenicconsidering that the majority of these compounds are bio-logically active substances that are synthesized to use themin agriculture industry and medicine The main source ofthese emerging pollutants is the residual urbanwaters and thewastewater treatment plants effluents because many of these

WWTPs are not designed or optimized to treat this kind ofcompounds [3]

Hormones are one of the most potent endocrine disrupt-ing compounds as well as are considered also as emergingpollutants Hormones can be differentiated in oestrogensandrogens and progestogens Some of them have limits intheir use but not a specific legislation [4]

The main characteristic of these pollutants is that it isnot necessary to remain in the environment to cause negativeeffects in view of the fact that their constant introduction init offsets their removal or degradation [5]

The steroid hormones help controlling the metabolisminflammations immunological functions water and salt bal-ance sexual development and the capacity of withstandingillnesses [6] The term steroid can be used for naturalhormones produced by the body as well as for artificiallyproduced medicines that increase the natural steroid effect

2 Journal of Analytical Methods in Chemistry

In the last 50 years the natural and synthetic hormoneworldwide consumption has grown as much as in humanmedicine as in cattle farming and they become the mostprescribed medicines [7]

A significant quantity of consumed oestrogens leaves theorganism through excretions For example 17120573-estradiol (E2)is oxidized rapidly becoming an estrone (E1) that can turninto estriol afterwards (E3) Besides the 17120572-ethinyl estradiol(EE) is excreted as conjugated [8]

With regard to emission sources in the first place arethe wastewater treatment plants (WWTPs) [9] and secon-darily cattle waste such as those leachates from dung anduncontrolled dumping [10] Several studies made in theWWTPs have reported that the treatment plants are capableof eliminating around 60 of hormones [11ndash13]

The identification of hormone residues in environmentis of special interest because knowledge of these compoundsis a requirement to take measures in order to regulate andminimize their environmental impact

However measurement of hormone residues is a verydifficult task not only due to the difficulty in measuringvery low concentration but also due to a very complexityof the samples Therefore use of mass spectrometer (MS)as detector coupled with chromatography techniques hasbecome a powerful method for the analysis of these typesof compounds at trace levels [14ndash17] Consequently LC-MSMS is the principally chosen technique One of the mainadvantages of LC-MSMS is its ability to analyze hormoneswithout derivatization (necessary in GC) or the need ofhydrolyze the conjugated form

Due to low level concentration of these compounds inenvironmental water it is necessary to apply an extractionand preconcentration method prior to LC analysis The mostused technique of extraction and preconcentration methodfor liquid samples is the solid phase extraction (SPE) [18ndash20]

The objective of this study is to develop a rapid and simpleprocedure of extraction preconcentration and determina-tion of four steroid oestrogens (estrone (E1) 17120573-estradiol(E2) estriol (E3) and 17120572-ethinylestradiol (EE)) one non-steroidal oestrogen the diethylstilbestrol (DES) one andro-gen the testosterone (TES) and two synthetic progestogensnorgestrel (NOR) and megestrol acetate (MGA) (Table 1)based on solid phase extraction and ultrahigh performanceliquid chromatography-tandem mass spectrometry (SPE-UHPLC-MSMS) The developed method was applied tothe identification and quantification of these compoundsin wastewater samples obtained from the influents andeffluents of two wastewater treatment plants (WWTPs) ofGran Canaria (Spain) They presented different methodsof wastewater treatments WWTP 1 presented a traditionalmethod based on activated sludge while WWTP 2 used amembrane bioreactor technique

2 Materials and Methods

21 Reagents All of the hormonal compounds usedwere pur-chased from Sigma-Aldrich (Madrid Spain) Stock solutionscontaining 1000mgsdotLminus1 of each analyte were prepared by

dissolving the compound inmethanol and the solutionswerestored in glass-stoppered bottles at 4∘C prior to use Workingaqueous standard solutions were prepared daily Ultrapurewater was provided by a Milli-Q system (Millipore BedfordMA USA) HPLC-grade methanol LC-MS methanol andLC-MS water as well as the ammonia and the ammoniumacetate used to adjust the pH of the mobile phases wereobtained from Panreac Quımica (Barcelona Spain)

22 Sample Collection Water samples were collected fromthe effluents of twowastewater treatment plants located in thenorthern area of Gran Canaria in May and August of 2012WWTP 1 used a conventional activated sludge treatmentsystem while WWTP 2 employed a membrane bioreactortreatment system The samples were collected in 2 L amberglass bottles that were rinsed beforehand with methanol andultrapurewater Samples were purified through filtrationwithfibreglass filters and then with 065 120583m membrane filters(Millipore Ireland) The samples were stored in the dark at4∘C and extracted within 48 hours

23 Instrumentation For the SPE optimization the instru-ment used was an ultrahigh performance liquid chromatog-raphy with fluorescence detector (UHPLC-FD) system con-sisting of an ACQUITYQuaternary Solvent Manager (QSM)used to load samples and wash and recondition the analyticalcolumn an autosampler a column manager and a fluores-cence detector with excitation and emission wavelengths of280 and 310 nm respectively all fromWaters (Madrid Spain)

The analysis of wastewater samples was performed ina UHPLC-MSMS system from Waters (Madrid Spain)similar to the described above with a 2777 autosamplerequipped with a 25120583L syringe and a tray to hold 2mLvials and an ACQUITY tandem triple quadrupole (TQD)mass spectrometer with an electrospray ionization (ESI)interface All Waters components (Madrid Spain) werecontrolled using the MassLynx Mass Spectrometry SoftwareElectrospray ionisation parameters were fixed as followsthe capillary voltage was 3 kV in positive mode and minus2 kVin negative mode the source temperature was 150∘C thedesolvation temperature was 500∘C and the desolvation gasflow rate was 1000 Lhr Nitrogen was used as the desolvationgas and argon was employed as the collision gas

The detailed MSMS detection parameters for each hor-monal compound are presented in Table 2 and were opti-mised by the direct injection of a 1mgsdotLminus1 standard solutionof each analyte into the detector at a flow rate of 10 120583Lsdotminminus1

24 Chromatographic Conditions For the SPE optimizationthe analytical column was a 50mm times 21mm ACQUITYUHPLCBEHWaters C

18columnwith a particle size of 17120583m

(Waters Chromatography Barcelona Spain) operating at atemperature of 30∘C Analytes separation was carried outemploying the following gradient starting at 55 45 (vv)water methanol for 1 minute During 3 minutes it changedto 50 50 (vv) and stayed for 25 minutes more Finally cameback to initial conditions in 1 minute and stayed for 15

Journal of Analytical Methods in Chemistry 3

Table 1 List of hormonal compounds pKa values chemical structure and retention times

Compound pKa [21] Structure 119905119877

(min)

E3 Estriol 103

HO

OH

OH

H H

H096

E2 17120573-estradiol 103

HO

OH

H H

H218

EE 17120572-ethinylestradiol 103

HO

HO

H H

H223

E1 Estrone 103

HO

O

H

H H220

DES Diethylstilbestrol 102

HO

OH

235

TES Testosterone 151

OH

OH H

H240

MGA Megestrol acetate

O

O

O

OH

H

H306

NOR Levonorgestrel 131

OH

O

H

H

H

H263

minutes Therefore the analysis took 9 minutes at a flow of05mLsdotminminus1

For the analysis of real samples aUHPLC-MSMS systemwas used The analytical column was the same and themobile phase was water and methanol adjusted with a bufferconsisting in 01 vv ammonia and 15mM of ammoniumacetate The analysis was performed in gradient mode at aflow rate of 03mLsdotminminus1The gradient started at 50 50 (vv)mixture of water methanol which changed to 25 75 (vv) in3 minutes and returned to 50 50 in 1 minute more Finallythe gradient stayed calibrating for another 15 minutes moreThe sample volume injected was 5120583L

3 Results and Discussion

31 Optimization of Solid-Phase Extraction (SPE) There area number of parameters that affect SPE procedure such as

type of sorbent pH ionic strength sample and desorptionvolumes and wash step To optimize these parameters itused Milli-Q water spiked with a solution of fluorescenceoestrogens (estriol 17120573-estradiol and 17120572-ethinylestradiol)to obtain a final concentration of 250120583gsdotLminus1

The first parameter to optimize is the choice of sorbentsince it controls the selectivity affinity and capacity overanalytes In this study the SPE cartridges used were OASISHLB SepPak C

18(both from Waters Madrid Spain) and

BondElut ENV (fromAgilent Madrid Spain) Keeping otherparameters fixed (ionic strength of 0 sample volume of100mL) the cartridges were studied at three different pHs(5 8 and 11) From the results obtained it can be observedthat the better signals are found for SepPak C

18cartridge

(Figure 1)After choosing the optimum cartridge we used an initial

experimental design of 23 to study the influence of pH ionic

4 Journal of Analytical Methods in Chemistry

Table 2 Mass spectrometer parameters for the determination of target analytes

Compound Precursor ion(mz)

Capillary voltage(Ion mode)

Quantification ionmz(collision potential V)

Quantification ionmz(collision potential V)

E3 2872 minus65V (ESI minus) 1710 (37) 1452 (39)E2 2712 minus65V (ESI minus) 1451 (40) 1831 (31)EE 2952 minus60V (ESI minus) 1450 (37) 1589 (33)E1 2692 minus65V (ESI minus) 1450 (36) 1430 (48)DES 2671 minus50V (ESI minus) 2371 (29) 2511 (25)TES 2892 38V (ESI +) 1870 (18) 1040 (21)MGA 3855 30V (ESI +) 2673 (15) 2242 (30)NOR 3132 38V (ESI +) 1090 (26) 2451 (18)

0

500

1000

1500

2000

2500

E3 E2 EE

Peak

area

Cartridge optimizationOASIS HLB pH = 5

OASIS HLB pH = 8

OASIS HLB pH = 11SepPak C18 pH = 5

SepPak C18 pH = 8

SepPak C18 pH = 11BondElut ENV pH = 5

BondElut ENV pH = 8

BondElut ENV pH =11

Figure 1 Optimization of SPE cartridges

strength and sample volume over extraction process Theexperimental design was obtained using Statgraphics Plussoftware 51 and the statistics study was done with IBM SPSSStatistics 19 We assessed two levels and three parameters pH(3 and 8) ionic strength (0 and 30 of NaCl) and samplevolume (50 and 250mL) to obtain the influence of eachparameter and the variable correlation to each other In thisstudy it is observed that the ionic strength and sample volumehad the major influence on the recoveries of the analytesFor that a 32 factorial design to optimize these two variablesat three levels per parameter (0 15 and 30 of NaCl forionic strength and 50 100 y 250mL for sample volume) wasused Figure 2 shows the response surface obtained for theestriol and 17120572-ethinylestradiol The results obtained showedthat an increment of the ionic strength did not producean increase in the response area of the compound and theoptimum volume was 250mL Because of that a solutionwithout salt addition and 250mL of sample volume waschosen Finally the desorption volume (1mLofmethanol and2mL of methanol in one and two steps) and wash-step (5mL

ofMilli-Q water and 5mL ofMilli-Q water with 5 and 10 ofmethanol vv) were assayed to complete the optimization ofthe SPE process The optimum values were 2mL of methanolin one step and 5mL of Milli-Q water without methanolrespectively

In accordance with the obtained results the optimumconditions for SPE procedure were SepPak C

18cartridge

250mL of sample at pH = 8 and 0 of NaCl desorptionwith 2mL of methanol in one step and wash step with5mL of Milli-Q water In these conditions we achieved apreconcentration factor of 125 In Figure 3 a chromatogramwith the optimum conditions is shown where the peaksof all compounds in their corresponding transitions can beobserved

32 Analytical Parameters Because of the SPE optimizationthat was done only with fluorescent compounds (estriol 17120573-estradiol and 17120572-ethinylestradiol) it was necessary to studythe recoveries of all the hormonal compounds using theoptimized SPE-UHPLC-MSMSmethod All the compoundsunder study showed good recoveries over 73 except thediethylstilbestrol with a recovery of 507

A calibration curve was used for the quantification ofthe analytes by diluting the stock solution of each analyteinto the samples to concentrations ranging between 1 and100 120583gsdotLminus1 Analysis was conducted by UHPLC-MSMS andlinear calibration plots for each analyte (1199032 gt 099) wereobtained based on their chromatographic peak areas

The limit of detection (LOD) and the limit of quantifi-cation (LOQ) for each compound were calculated from thesignal-to-noise ratio of each individual peak The LOD wasdefined as the lowest concentration that gave a signal-to-noiseratio that was greater than 3 The LOQ was defined as thelowest concentration that gave a signal to noise ratio that wasgreater than 10The LODs ranged from015 to 935 ngsdotLminus1 andthe LOQs ranged from 049 to 3118 ngsdotLminus1

The performance and reliability of the process werestudied by determining the repeatability of the quantificationresults for all target analytes under the described conditionsusing six samples (119899 = 6) The relative standard deviations(RSDs) were lower than 84 in all cases indicating a

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 12: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Journal of Analytical Methods in Chemistry 5

0

500

1000

1500

4000

6000

8000

10000

Con

cent

ratio

ns (n

gL)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

sum15PAEssum6PAEs

Figure 4 Spatial distributions of the 16 sampling sites near theMopanshan Reservoir

the exception of site 2 3 and 11 contributions ranging from331 to 963 followed byDBP ranging from 21 to 363The results are consistent with the above data for overallanalysis that DBP and DEHP are the dominant componentsof the PAEs distribution pattern in each sampling site whichreflected the different pattern of plastic contaminant inputduring the sampling period Similarly DIBP and DBP areused in epoxy resins or special adhesive formulations withthe different proportions of these two PAE congeners whichwere also the important indicator of the information pollutedby PAEs for the sampling locations Although the limitedsample number draws only limited conclusions there is stillreason to note that a leaching from the plastic materials intothe runoff water is possible and that water runoff from thecontaminated water is a burden pathway from differentsources of PAEs [14]

33 Comparison with Other Water Bodies Comparison withthe total PAEs concentrations is nevertheless very limited dueto the different analysis compounds However the individualPAE namely DBP and DEHP is by far the most abundantin other researches and it is possible to make a camparisonwith our findings In this case the results of DBP and DEHPconcentrations published in literatures for kinds of waterbodies are presented together in Table 3

The DEHP and DBP concentrations of the present studyshowed to some extent lower concentration levels than thosereported in the other water bodies in China In comparisonthe results were comparable or similar to those from theexaminations described in other foreign countries For exam-ple as shown in Table 3 the DEHP concentrations were sim-ilar to the surface waters from the Netherlands and Italydescribed in the literature Meanwhile these concentrationsin this study were quite lower than the Yangtze River andSecond Songhua River in China

0

20

40

60

80

100

DEEP DPP DHXP DEHP DNOP DBP

DIBP DEP DMP

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Sampling site

Com

posit

ion

()

Figure 5 PAE composition of thewater samples in 16 sampling sites

In conclusion as compared to the results of other studiesthe waters near the Mopanshan Reservoir were moderatelypolluted by PAEs Therefore there is a definite need to set upa properly planned and systematic approach to water controlnear the Mopanshan Reservoir

34 PAE Levels in the Waterworks The Mopanshan Water-works (MPSW) equipped essentially with the water sourceof the Mopanshan Reservoir has been investigated in orderto assess the fate of the PAEs during the drinking watertreatment process For comparison a sampling campaign forthe determination of PAEs levels in the Seven Waterworks(SW waterworks with the old water source of the SonghuaRiver) was carried out Both waterworks operate coagulationsedimentation and followed by filtration treatment processwhich are typical traditional drinking water treatment

The measured concentrations in the raw and finishedwater of the two investigated waterworks are shown inFigure 6 Six out of fifteen PAEs were detected in the fin-ished water from the two waterworks The detected PAEswere DMP DEP DIBP DBP DEHP and DNOP and theother investigated phthalates are of minor importance withconcentrations all below the limit of detection As showin Figure 6 the measured concentrations of the analyzedPAEs in the finished water of the two waterworks variedstronglyThemost important compound in the finishedwaterwas DEHP with the mean concentration of 34737 and40592 ngL for the MPSW and SW respectively suggestingthe highest relative composition of total PAE concentrationsin the drinking water

For the raw water from the different water sources DMPand DIBP concentrations in the MPSW were much lowerthan the ones in the SW and the concentrations of DEPDBP DEHP andDEHPwere relatively comparable in the two

6 Journal of Analytical Methods in Chemistry

Table 3 Comparison of the concentrations of DEHP and DBP in the water bodies (ngL)

Location DEHP DBP ReferenceRange Median Mean Range Median Mean

Surface water Germany 330ndash97800 2270 mdash 120ndash8800 500 mdash [14]Surface water the Netherlands ndndash5000 320 mdash 66ndash3100 250 mdash [15]Seine River estuary France 160ndash314 mdash mdash 67ndash319 mdash mdash [16]Tama River Japan 13ndash3600 mdash mdash 8ndash540 mdash mdash [17]Velino River Italy ndndash6400 mdash mdash ndndash44300 mdash mdash [2]Surface water Taiwan ndndash18500 mdash 9300 1000ndash13500 mdash 4900 [18]Surface water Jiangsu China 556ndash156707 mdash mdash 16ndash58575 mdash mdash [19]Yangtze River mainstream China 3900ndash54730 mdash mdash ndndash35650 mdash mdash [20]Middle and lower Yellow River China 347ndash31800 mdash mdash ndndash26000 mdash mdash [21]Second Songhua River China ndndash1752650 370020 mdash ndndash5616800 mdash 717240 [22]Urban lakes Guangzhou China 87ndash630 170 240 940ndash3600 1990 2030 [11]Xiangjiang River China 620ndash15230 mdash mdash mdash mdash mdash [23]This study 1289ndash65709 6710 17741 525ndash44982 1103 8014

0

500

1000

100001200014000

0

20

40

60

80

100

Raw waterFinished waterRemoval

Rem

oval

()

Con

cent

ratio

ns (n

gL)

DMP DEP DIBP DBP DEHP DNOP

(a)

Raw waterFinished waterRemoval

0

500

1000

1500

2000

100001200014000

0

20

40

60

80

100C

once

ntra

tions

(ng

L)

Rem

oval

()

DMP DEP DIBP DBP DEHP DNOP

(b)

Figure 6 PAEs detected in the water samples from the MPSW (a) and SW (b)

waterworks The removal of PAEs by these two waterworksranged from 258 to 765 which varied significantly with-out stable removal efficienciesThe lower removal efficienciesfor DMP and DNOP were observed in the SW with theremoval less than 30 For both the waterworks no soundremoval efficiencies were obtained for the PAEs indicatingthat the traditional drinking water treatment cannot showgood performance to eliminate these micro pollutants whichhas nothing to do with the type of the water source

Traditional drinking water treatment focuses on dealingwith the particles and colloids in terms of physical processesMany studies of the environmental fates of PAEs have demon-strated that oxidation or microbial action is the principalmechanism for their removal in the aquatic systems [24ndash26]Therefore the treatment process should be the combinationswith the key techniques for removing PAEs from the waterOn the other hand since the removal efficiencies of PAEs by

these advance drinking water treatments in waterworks hasnot been systematically studied to date further research inthis direction would seem to be required

35 Exposure Assessment of PAEs in Water To evaluate thepotential and adverse effects of PAEs quality guidelines forsurface water and drinking water standard were used Theresults indicated that the mean concentrations of DBP andDEHP at levels were well below the reference doses (RfD)regarded as unsafe by the EPA for the surface water Thelevels were not also above the RfD recommended by China(Environmental Quality Standard for SurfaceWater of ChinaGB3838-2002) On the other hand the amounts of DEHPpresent in public water supplies should be lower than thedrinkingwater standard (0006mgL for EPA and 0008mgLfor China) According to the results the concentrations of

Journal of Analytical Methods in Chemistry 7

DEHP in drinkingwater samples from theMPSWwere lowerthan the limited value

PAEs are also considered to be endocrine disruptingchemicals (EDCs) whose effects may not appear until long-term exposure According to the results PAEs were detectedin the drinking water constantly ingested in daily life indi-cating that drinking water is an important source of humanexposure to PAEs contaminants Assuming a daily waterconsumption rate of 2 L and an average body weight of 60 kgfor adults the average daily intake of DEHP DBP and DIBPby way of drinking water from MPSW was calculated to be1158 1352 and 81 ngkgd respectively In comparison thevalues of SW with the water source of the Songhua Riverwere relatively higher with the calculated results of 1353140 and 155 ngkgd for DEHP DBP and DIBP respectivelyIn this study the estimated daily intake levels of DEHPfrom the drinking water were quite lower than the RfDof 20000 ngkgd released by the EPA However some ofPAEs are partly metabolised in the organism and futureexperiments should be focused on determining the potentialeffects of the metabolites [27]

Currently treated water from the Songhua River is fornonpotable uses and MPSW is the exclusive waterworks runfor the water supply of Harbin city However populationgrowth and drought cycle are limited by the availability of rawwater from theMopanshan Reservoir Tomeet the increasingdemand local and regional water authorities have begun acampaign of second water supply project from the SonghuaRiver again which needs the protection of the Songhua Riverand advanced water treatment for the source

4 Conclusions

This study provided the first detailed data on the contami-nation status of 15 PAEs in the water near the MopanshanReservoir The concentration range of 15 PAEs in the sampleswas from 3558 to 92265 ngL with the mean value of29431 ngL DEHP andDBPwere themain pollutants among15 PAEs accounting for the main watershed pollution Theoccurrence and distribution of PAEs from different samplingsites in the water source varied largely suggesting that thespatial distribution of PAEs was site specific In additionthe monitoring of PAEs in the waterworks also showed thatPAEs can be detected in the drinking water and certaintoxicological risks to drinking water consumers were foundThese results reported here contribute to an understandingof how PAE contaminants are distributed in the new watersource and the waterworks in Harbin city as well as forminga basis for further modeling risk assessment and selection ofdrinking water treatment technology

In conclusion the results implied that no urgent reme-diation measures were required with respect to PAEs in thewaters However the ecological and health effects of thesesubstances through drinkingwater at the relatively lower con-centrations still need further notice in light of their possiblebiological magnifications Therefore the long-term sourcecontrol in the water and adding advanced treatment processfor drinking water supplies should be given special attentionin this area

Acknowledgments

This work was supported by the National Natural ScienceFoundation of China (1077029) the Funds for CreativeResearch Groups of China (Grant no 51121062) the NationalNatural Science Foundation of China (51078105) and theOpen Project of the State Key Laboratory of Urban WaterResource and Environment Harbin Institute of Technology(no QA201019)

References

[1] M Nikonorow H Mazur and H Piekacz ldquoEffect of orallyadministered plasticizers and polyvinyl chloride stabilizers inthe ratrdquo Toxicology and Applied Pharmacology vol 26 no 2 pp253ndash259 1973

[2] M Vitali M Guidotti G Macilenti and C Cremisini ldquoPhtha-late esters in freshwaters asmarkers of contamination sourcesmdasha site study in ItalyrdquoEnvironment International vol 23 no 3 pp337ndash347 1997

[3] G Latini C de Felice G Presta et al ldquoIn utero exposure todi-(2-ethylhexyl)phthalate and duration of human pregnancyrdquoEnvironmental Health Perspectives vol 111 no 14 pp 1783ndash17852003

[4] C E Mackintosh J A Maldonado M G Ikonomou and F AP C Gobas ldquoSorption of phthalate esters and PCBs in a marineecosystemrdquo Environmental Science and Technology vol 40 no11 pp 3481ndash3488 2006

[5] M Clara G Windhofer W Hartl et al ldquoOccurrence of phtha-lates in surface runoff untreated and treated wastewater andfate during wastewater treatmentrdquo Chemosphere vol 78 no 9pp 1078ndash1084 2010

[6] M M Abdel Daiem J Rivera-Utrilla R Ocampo-Perez J DMendez-Dıaz andM Sanchez-Polo ldquoEnvironmental impact ofphthalic acid esters and their removal fromwater and sedimentsby different technologiesmdasha reviewrdquo Journal of EnvironmentalManagement vol 109 pp 164ndash178 2012

[7] L Chen Y Zhao L Li B Chen and Y Zhang ldquoExposureassessment of phthalates in non-occupational populations inChinardquo Science of the Total Environment vol 427-428 pp 60ndash69 2012

[8] M J Teil M Blanchard andM Chevreuil ldquoAtmospheric fate ofphthalate esters in an urban area (Paris-France)rdquo Science of theTotal Environment vol 354 no 2-3 pp 212ndash223 2006

[9] P Roslev K Vorkamp J Aarup K Frederiksen and P HNielsen ldquoDegradation of phthalate esters in an activated sludgewastewater treatment plantrdquo Water Research vol 41 no 5 pp969ndash976 2007

[10] J Gasperi S Garnaud V Rocher and R Moilleron ldquoPrioritypollutants in wastewater and combined sewer overflowrdquo Scienceof the Total Environment vol 407 no 1 pp 263ndash272 2008

[11] F Zeng K Cui Z Xie et al ldquoOccurrence of phthalate estersin water and sediment of urban lakes in a subtropical cityGuangzhou South Chinardquo Environment International vol 34no 3 pp 372ndash380 2008

[12] F Zeng K Cui Z Xie et al ldquoPhthalate esters (PAEs) emergingorganic contaminants in agricultural soils in peri-urban areasaround Guangzhou Chinardquo Environmental Pollution vol 156no 2 pp 425ndash434 2008

[13] G Wildbrett ldquoDiffusion of phthalic acid esters from PVC milktubingrdquo Environmental Health Perspectives vol 3 pp 29ndash351973

8 Journal of Analytical Methods in Chemistry

[14] H Fromme T Kuchler T Otto K Pilz J Muller and AWenzel ldquoOccurrence of phthalates and bisphenol A and F inthe environmentrdquoWater Research vol 36 no 6 pp 1429ndash14382002

[15] A D Vethaak J Lahr S M Schrap et al ldquoAn integrated assess-ment of estrogenic contamination and biological effects in theaquatic environment ofTheNetherlandsrdquoChemosphere vol 59no 4 pp 511ndash524 2005

[16] C Dargnat M Blanchard M Chevreuil andM J Teil ldquoOccur-rence of phthalate esters in the Seine River estuary (France)rdquoHydrological Processes vol 23 no 8 pp 1192ndash1201 2009

[17] T Suzuki K Yaguchi S Suzuki and T Suga ldquoMonitoring ofphthalic acid monoesters in river water by solid-phase extrac-tion and GC-MS determinationrdquo Environmental Science andTechnology vol 35 no 18 pp 3757ndash3763 2001

[18] S Y Yuan C Liu C S Liao and B V Chang ldquoOccurrenceand microbial degradation of phthalate esters in Taiwan riversedimentsrdquo Chemosphere vol 49 no 10 pp 1295ndash1299 2002

[19] B Li C Qu and J Bi ldquoIdentification of trace organic pollutantsin drinking water and the associated human health risks inJiangsu Province Chinardquo Bulletin of Environmental Contami-nation and Toxicology pp 1ndash5 2012

[20] F Wang X Xia and Y Sha ldquoDistribution of phthalic acidesters in Wuhan section of the Yangtze River Chinardquo Journalof Hazardous Materials vol 154 no 1ndash3 pp 317ndash324 2008

[21] Y J Sha X H Xia and X Q Xiao ldquoDistribution characters ofphthalic acid ester in the waters middle and lower reaches ofthe Yellow Riverrdquo China Environmental Science vol 26 no 1pp 120ndash124 2006

[22] J Lu L-B Hao C-Z Wang W Li R-J Bai and D YanldquoDistribution characteristics of phthalic acid esters in middleand lower reaches of no 2 Songhua Riverrdquo EnvironmentalScience amp Technology vol 12 article 014 2007

[23] X J Zhu and Y Y Qiu ldquoMeasuring the phthalates of xiangjiangriver using liquid-liquid extraction gas chromatographyrdquoAdvanced Materials Research vol 301 pp 752ndash755 2011

[24] B L Yuan X Z Li and N Graham ldquoAqueous oxida-tion of dimethyl phthalate in a Fe(VI)-TiO

2

-UV reaction sys-temrdquoWater Research vol 42 no 6-7 pp 1413ndash1420 2008

[25] Z Yunrui ZWanpeng L FudongW Jianbing and Y ShaoxialdquoCatalytic activity of RuAl2O3 for ozonation of dimethylphthalate in aqueous solutionrdquo Chemosphere vol 66 no 1 pp145ndash150 2007

[26] H N Gavala U Yenal and B K Ahring ldquoThermal andenzymatic pretreatment of sludge containing phthalate estersprior tomesophilic anaerobic digestionrdquoBiotechnology and Bio-engineering vol 85 no 5 pp 561ndash567 2004

[27] Y Guo Q Wu and K Kannan ldquoPhthalate metabolites in urinefrom China and implications for human exposuresrdquo Environ-ment International vol 37 no 5 pp 893ndash898 2011

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 210653 8 pageshttpdxdoiorg1011552013210653

Research ArticleSimultaneous Determination of Hormonal Residuesin Treated Waters Using Ultrahigh Performance LiquidChromatography-Tandem Mass Spectrometry

Rayco Guedes-Alonso Zoraida Sosa-Ferrera and Joseacute Juan Santana-Rodriacuteguez

Departamento de Quımica Universidad de Las Palmas de Gran Canaria 35017 Las Palmas de Gran Canaria Spain

Correspondence should be addressed to Jose Juan Santana-Rodrıguez jsantanadquiulpgces

Received 28 December 2012 Accepted 7 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Rayco Guedes-Alonso et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

In the last years hormone consumption has increased exponentially Because of that hormone compounds are considered emergingpollutants since several studies have determinted their presence in water influents and effluents of wastewater treatment plants(WWTPs) In this study a quantitative method for the simultaneous determination of oestrogens (estrone 17120573-estradiol estriol17120572-ethinylestradiol and diethylstilbestrol) androgens (testosterone) and progestogens (norgestrel andmegestrol acetate) has beendeveloped to determine these compounds in wastewater samples Due to the very low concentrations of target compounds in theenvironment a solid phase extraction procedure has been optimized and developed to extract and preconcentrate the analytesDetermination and quantification were performed by ultrahigh performance liquid chromatography-tandem mass spectrometry(UHPLC-MSMS) The method developed presents satisfactory limits of detection (between 015 and 935 ngsdotLminus1) good recoveries(between 73 and 90 for the most of compounds) and low relative standard deviations (under 84) Samples from influents andeffluents of two wastewater treatment plants of Gran Canaria (Spain) were analyzed using the proposed method finding severalhormones with concentrations ranged from 5 to 300 ngsdotLminus1

1 Introduction

In general it is supposed that more than 100000 differentchemical compounds can be introduced in the Environmentmany of them in very small quantity However a lot of thesecompounds are not included as pollutants in the legislationAlthough these compounds named emerging pollutants arenot regulated as pollutants they probably will be in the futurebecause of their potential negative effect in the ecosystem For20 years many articles have reported the presence of theseldquonew compoundsrdquo in wastewater [1 2]

The emerging pollutant origin is mainly anthropogenicconsidering that the majority of these compounds are bio-logically active substances that are synthesized to use themin agriculture industry and medicine The main source ofthese emerging pollutants is the residual urbanwaters and thewastewater treatment plants effluents because many of these

WWTPs are not designed or optimized to treat this kind ofcompounds [3]

Hormones are one of the most potent endocrine disrupt-ing compounds as well as are considered also as emergingpollutants Hormones can be differentiated in oestrogensandrogens and progestogens Some of them have limits intheir use but not a specific legislation [4]

The main characteristic of these pollutants is that it isnot necessary to remain in the environment to cause negativeeffects in view of the fact that their constant introduction init offsets their removal or degradation [5]

The steroid hormones help controlling the metabolisminflammations immunological functions water and salt bal-ance sexual development and the capacity of withstandingillnesses [6] The term steroid can be used for naturalhormones produced by the body as well as for artificiallyproduced medicines that increase the natural steroid effect

2 Journal of Analytical Methods in Chemistry

In the last 50 years the natural and synthetic hormoneworldwide consumption has grown as much as in humanmedicine as in cattle farming and they become the mostprescribed medicines [7]

A significant quantity of consumed oestrogens leaves theorganism through excretions For example 17120573-estradiol (E2)is oxidized rapidly becoming an estrone (E1) that can turninto estriol afterwards (E3) Besides the 17120572-ethinyl estradiol(EE) is excreted as conjugated [8]

With regard to emission sources in the first place arethe wastewater treatment plants (WWTPs) [9] and secon-darily cattle waste such as those leachates from dung anduncontrolled dumping [10] Several studies made in theWWTPs have reported that the treatment plants are capableof eliminating around 60 of hormones [11ndash13]

The identification of hormone residues in environmentis of special interest because knowledge of these compoundsis a requirement to take measures in order to regulate andminimize their environmental impact

However measurement of hormone residues is a verydifficult task not only due to the difficulty in measuringvery low concentration but also due to a very complexityof the samples Therefore use of mass spectrometer (MS)as detector coupled with chromatography techniques hasbecome a powerful method for the analysis of these typesof compounds at trace levels [14ndash17] Consequently LC-MSMS is the principally chosen technique One of the mainadvantages of LC-MSMS is its ability to analyze hormoneswithout derivatization (necessary in GC) or the need ofhydrolyze the conjugated form

Due to low level concentration of these compounds inenvironmental water it is necessary to apply an extractionand preconcentration method prior to LC analysis The mostused technique of extraction and preconcentration methodfor liquid samples is the solid phase extraction (SPE) [18ndash20]

The objective of this study is to develop a rapid and simpleprocedure of extraction preconcentration and determina-tion of four steroid oestrogens (estrone (E1) 17120573-estradiol(E2) estriol (E3) and 17120572-ethinylestradiol (EE)) one non-steroidal oestrogen the diethylstilbestrol (DES) one andro-gen the testosterone (TES) and two synthetic progestogensnorgestrel (NOR) and megestrol acetate (MGA) (Table 1)based on solid phase extraction and ultrahigh performanceliquid chromatography-tandem mass spectrometry (SPE-UHPLC-MSMS) The developed method was applied tothe identification and quantification of these compoundsin wastewater samples obtained from the influents andeffluents of two wastewater treatment plants (WWTPs) ofGran Canaria (Spain) They presented different methodsof wastewater treatments WWTP 1 presented a traditionalmethod based on activated sludge while WWTP 2 used amembrane bioreactor technique

2 Materials and Methods

21 Reagents All of the hormonal compounds usedwere pur-chased from Sigma-Aldrich (Madrid Spain) Stock solutionscontaining 1000mgsdotLminus1 of each analyte were prepared by

dissolving the compound inmethanol and the solutionswerestored in glass-stoppered bottles at 4∘C prior to use Workingaqueous standard solutions were prepared daily Ultrapurewater was provided by a Milli-Q system (Millipore BedfordMA USA) HPLC-grade methanol LC-MS methanol andLC-MS water as well as the ammonia and the ammoniumacetate used to adjust the pH of the mobile phases wereobtained from Panreac Quımica (Barcelona Spain)

22 Sample Collection Water samples were collected fromthe effluents of twowastewater treatment plants located in thenorthern area of Gran Canaria in May and August of 2012WWTP 1 used a conventional activated sludge treatmentsystem while WWTP 2 employed a membrane bioreactortreatment system The samples were collected in 2 L amberglass bottles that were rinsed beforehand with methanol andultrapurewater Samples were purified through filtrationwithfibreglass filters and then with 065 120583m membrane filters(Millipore Ireland) The samples were stored in the dark at4∘C and extracted within 48 hours

23 Instrumentation For the SPE optimization the instru-ment used was an ultrahigh performance liquid chromatog-raphy with fluorescence detector (UHPLC-FD) system con-sisting of an ACQUITYQuaternary Solvent Manager (QSM)used to load samples and wash and recondition the analyticalcolumn an autosampler a column manager and a fluores-cence detector with excitation and emission wavelengths of280 and 310 nm respectively all fromWaters (Madrid Spain)

The analysis of wastewater samples was performed ina UHPLC-MSMS system from Waters (Madrid Spain)similar to the described above with a 2777 autosamplerequipped with a 25120583L syringe and a tray to hold 2mLvials and an ACQUITY tandem triple quadrupole (TQD)mass spectrometer with an electrospray ionization (ESI)interface All Waters components (Madrid Spain) werecontrolled using the MassLynx Mass Spectrometry SoftwareElectrospray ionisation parameters were fixed as followsthe capillary voltage was 3 kV in positive mode and minus2 kVin negative mode the source temperature was 150∘C thedesolvation temperature was 500∘C and the desolvation gasflow rate was 1000 Lhr Nitrogen was used as the desolvationgas and argon was employed as the collision gas

The detailed MSMS detection parameters for each hor-monal compound are presented in Table 2 and were opti-mised by the direct injection of a 1mgsdotLminus1 standard solutionof each analyte into the detector at a flow rate of 10 120583Lsdotminminus1

24 Chromatographic Conditions For the SPE optimizationthe analytical column was a 50mm times 21mm ACQUITYUHPLCBEHWaters C

18columnwith a particle size of 17120583m

(Waters Chromatography Barcelona Spain) operating at atemperature of 30∘C Analytes separation was carried outemploying the following gradient starting at 55 45 (vv)water methanol for 1 minute During 3 minutes it changedto 50 50 (vv) and stayed for 25 minutes more Finally cameback to initial conditions in 1 minute and stayed for 15

Journal of Analytical Methods in Chemistry 3

Table 1 List of hormonal compounds pKa values chemical structure and retention times

Compound pKa [21] Structure 119905119877

(min)

E3 Estriol 103

HO

OH

OH

H H

H096

E2 17120573-estradiol 103

HO

OH

H H

H218

EE 17120572-ethinylestradiol 103

HO

HO

H H

H223

E1 Estrone 103

HO

O

H

H H220

DES Diethylstilbestrol 102

HO

OH

235

TES Testosterone 151

OH

OH H

H240

MGA Megestrol acetate

O

O

O

OH

H

H306

NOR Levonorgestrel 131

OH

O

H

H

H

H263

minutes Therefore the analysis took 9 minutes at a flow of05mLsdotminminus1

For the analysis of real samples aUHPLC-MSMS systemwas used The analytical column was the same and themobile phase was water and methanol adjusted with a bufferconsisting in 01 vv ammonia and 15mM of ammoniumacetate The analysis was performed in gradient mode at aflow rate of 03mLsdotminminus1The gradient started at 50 50 (vv)mixture of water methanol which changed to 25 75 (vv) in3 minutes and returned to 50 50 in 1 minute more Finallythe gradient stayed calibrating for another 15 minutes moreThe sample volume injected was 5120583L

3 Results and Discussion

31 Optimization of Solid-Phase Extraction (SPE) There area number of parameters that affect SPE procedure such as

type of sorbent pH ionic strength sample and desorptionvolumes and wash step To optimize these parameters itused Milli-Q water spiked with a solution of fluorescenceoestrogens (estriol 17120573-estradiol and 17120572-ethinylestradiol)to obtain a final concentration of 250120583gsdotLminus1

The first parameter to optimize is the choice of sorbentsince it controls the selectivity affinity and capacity overanalytes In this study the SPE cartridges used were OASISHLB SepPak C

18(both from Waters Madrid Spain) and

BondElut ENV (fromAgilent Madrid Spain) Keeping otherparameters fixed (ionic strength of 0 sample volume of100mL) the cartridges were studied at three different pHs(5 8 and 11) From the results obtained it can be observedthat the better signals are found for SepPak C

18cartridge

(Figure 1)After choosing the optimum cartridge we used an initial

experimental design of 23 to study the influence of pH ionic

4 Journal of Analytical Methods in Chemistry

Table 2 Mass spectrometer parameters for the determination of target analytes

Compound Precursor ion(mz)

Capillary voltage(Ion mode)

Quantification ionmz(collision potential V)

Quantification ionmz(collision potential V)

E3 2872 minus65V (ESI minus) 1710 (37) 1452 (39)E2 2712 minus65V (ESI minus) 1451 (40) 1831 (31)EE 2952 minus60V (ESI minus) 1450 (37) 1589 (33)E1 2692 minus65V (ESI minus) 1450 (36) 1430 (48)DES 2671 minus50V (ESI minus) 2371 (29) 2511 (25)TES 2892 38V (ESI +) 1870 (18) 1040 (21)MGA 3855 30V (ESI +) 2673 (15) 2242 (30)NOR 3132 38V (ESI +) 1090 (26) 2451 (18)

0

500

1000

1500

2000

2500

E3 E2 EE

Peak

area

Cartridge optimizationOASIS HLB pH = 5

OASIS HLB pH = 8

OASIS HLB pH = 11SepPak C18 pH = 5

SepPak C18 pH = 8

SepPak C18 pH = 11BondElut ENV pH = 5

BondElut ENV pH = 8

BondElut ENV pH =11

Figure 1 Optimization of SPE cartridges

strength and sample volume over extraction process Theexperimental design was obtained using Statgraphics Plussoftware 51 and the statistics study was done with IBM SPSSStatistics 19 We assessed two levels and three parameters pH(3 and 8) ionic strength (0 and 30 of NaCl) and samplevolume (50 and 250mL) to obtain the influence of eachparameter and the variable correlation to each other In thisstudy it is observed that the ionic strength and sample volumehad the major influence on the recoveries of the analytesFor that a 32 factorial design to optimize these two variablesat three levels per parameter (0 15 and 30 of NaCl forionic strength and 50 100 y 250mL for sample volume) wasused Figure 2 shows the response surface obtained for theestriol and 17120572-ethinylestradiol The results obtained showedthat an increment of the ionic strength did not producean increase in the response area of the compound and theoptimum volume was 250mL Because of that a solutionwithout salt addition and 250mL of sample volume waschosen Finally the desorption volume (1mLofmethanol and2mL of methanol in one and two steps) and wash-step (5mL

ofMilli-Q water and 5mL ofMilli-Q water with 5 and 10 ofmethanol vv) were assayed to complete the optimization ofthe SPE process The optimum values were 2mL of methanolin one step and 5mL of Milli-Q water without methanolrespectively

In accordance with the obtained results the optimumconditions for SPE procedure were SepPak C

18cartridge

250mL of sample at pH = 8 and 0 of NaCl desorptionwith 2mL of methanol in one step and wash step with5mL of Milli-Q water In these conditions we achieved apreconcentration factor of 125 In Figure 3 a chromatogramwith the optimum conditions is shown where the peaksof all compounds in their corresponding transitions can beobserved

32 Analytical Parameters Because of the SPE optimizationthat was done only with fluorescent compounds (estriol 17120573-estradiol and 17120572-ethinylestradiol) it was necessary to studythe recoveries of all the hormonal compounds using theoptimized SPE-UHPLC-MSMSmethod All the compoundsunder study showed good recoveries over 73 except thediethylstilbestrol with a recovery of 507

A calibration curve was used for the quantification ofthe analytes by diluting the stock solution of each analyteinto the samples to concentrations ranging between 1 and100 120583gsdotLminus1 Analysis was conducted by UHPLC-MSMS andlinear calibration plots for each analyte (1199032 gt 099) wereobtained based on their chromatographic peak areas

The limit of detection (LOD) and the limit of quantifi-cation (LOQ) for each compound were calculated from thesignal-to-noise ratio of each individual peak The LOD wasdefined as the lowest concentration that gave a signal-to-noiseratio that was greater than 3 The LOQ was defined as thelowest concentration that gave a signal to noise ratio that wasgreater than 10The LODs ranged from015 to 935 ngsdotLminus1 andthe LOQs ranged from 049 to 3118 ngsdotLminus1

The performance and reliability of the process werestudied by determining the repeatability of the quantificationresults for all target analytes under the described conditionsusing six samples (119899 = 6) The relative standard deviations(RSDs) were lower than 84 in all cases indicating a

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 13: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

6 Journal of Analytical Methods in Chemistry

Table 3 Comparison of the concentrations of DEHP and DBP in the water bodies (ngL)

Location DEHP DBP ReferenceRange Median Mean Range Median Mean

Surface water Germany 330ndash97800 2270 mdash 120ndash8800 500 mdash [14]Surface water the Netherlands ndndash5000 320 mdash 66ndash3100 250 mdash [15]Seine River estuary France 160ndash314 mdash mdash 67ndash319 mdash mdash [16]Tama River Japan 13ndash3600 mdash mdash 8ndash540 mdash mdash [17]Velino River Italy ndndash6400 mdash mdash ndndash44300 mdash mdash [2]Surface water Taiwan ndndash18500 mdash 9300 1000ndash13500 mdash 4900 [18]Surface water Jiangsu China 556ndash156707 mdash mdash 16ndash58575 mdash mdash [19]Yangtze River mainstream China 3900ndash54730 mdash mdash ndndash35650 mdash mdash [20]Middle and lower Yellow River China 347ndash31800 mdash mdash ndndash26000 mdash mdash [21]Second Songhua River China ndndash1752650 370020 mdash ndndash5616800 mdash 717240 [22]Urban lakes Guangzhou China 87ndash630 170 240 940ndash3600 1990 2030 [11]Xiangjiang River China 620ndash15230 mdash mdash mdash mdash mdash [23]This study 1289ndash65709 6710 17741 525ndash44982 1103 8014

0

500

1000

100001200014000

0

20

40

60

80

100

Raw waterFinished waterRemoval

Rem

oval

()

Con

cent

ratio

ns (n

gL)

DMP DEP DIBP DBP DEHP DNOP

(a)

Raw waterFinished waterRemoval

0

500

1000

1500

2000

100001200014000

0

20

40

60

80

100C

once

ntra

tions

(ng

L)

Rem

oval

()

DMP DEP DIBP DBP DEHP DNOP

(b)

Figure 6 PAEs detected in the water samples from the MPSW (a) and SW (b)

waterworks The removal of PAEs by these two waterworksranged from 258 to 765 which varied significantly with-out stable removal efficienciesThe lower removal efficienciesfor DMP and DNOP were observed in the SW with theremoval less than 30 For both the waterworks no soundremoval efficiencies were obtained for the PAEs indicatingthat the traditional drinking water treatment cannot showgood performance to eliminate these micro pollutants whichhas nothing to do with the type of the water source

Traditional drinking water treatment focuses on dealingwith the particles and colloids in terms of physical processesMany studies of the environmental fates of PAEs have demon-strated that oxidation or microbial action is the principalmechanism for their removal in the aquatic systems [24ndash26]Therefore the treatment process should be the combinationswith the key techniques for removing PAEs from the waterOn the other hand since the removal efficiencies of PAEs by

these advance drinking water treatments in waterworks hasnot been systematically studied to date further research inthis direction would seem to be required

35 Exposure Assessment of PAEs in Water To evaluate thepotential and adverse effects of PAEs quality guidelines forsurface water and drinking water standard were used Theresults indicated that the mean concentrations of DBP andDEHP at levels were well below the reference doses (RfD)regarded as unsafe by the EPA for the surface water Thelevels were not also above the RfD recommended by China(Environmental Quality Standard for SurfaceWater of ChinaGB3838-2002) On the other hand the amounts of DEHPpresent in public water supplies should be lower than thedrinkingwater standard (0006mgL for EPA and 0008mgLfor China) According to the results the concentrations of

Journal of Analytical Methods in Chemistry 7

DEHP in drinkingwater samples from theMPSWwere lowerthan the limited value

PAEs are also considered to be endocrine disruptingchemicals (EDCs) whose effects may not appear until long-term exposure According to the results PAEs were detectedin the drinking water constantly ingested in daily life indi-cating that drinking water is an important source of humanexposure to PAEs contaminants Assuming a daily waterconsumption rate of 2 L and an average body weight of 60 kgfor adults the average daily intake of DEHP DBP and DIBPby way of drinking water from MPSW was calculated to be1158 1352 and 81 ngkgd respectively In comparison thevalues of SW with the water source of the Songhua Riverwere relatively higher with the calculated results of 1353140 and 155 ngkgd for DEHP DBP and DIBP respectivelyIn this study the estimated daily intake levels of DEHPfrom the drinking water were quite lower than the RfDof 20000 ngkgd released by the EPA However some ofPAEs are partly metabolised in the organism and futureexperiments should be focused on determining the potentialeffects of the metabolites [27]

Currently treated water from the Songhua River is fornonpotable uses and MPSW is the exclusive waterworks runfor the water supply of Harbin city However populationgrowth and drought cycle are limited by the availability of rawwater from theMopanshan Reservoir Tomeet the increasingdemand local and regional water authorities have begun acampaign of second water supply project from the SonghuaRiver again which needs the protection of the Songhua Riverand advanced water treatment for the source

4 Conclusions

This study provided the first detailed data on the contami-nation status of 15 PAEs in the water near the MopanshanReservoir The concentration range of 15 PAEs in the sampleswas from 3558 to 92265 ngL with the mean value of29431 ngL DEHP andDBPwere themain pollutants among15 PAEs accounting for the main watershed pollution Theoccurrence and distribution of PAEs from different samplingsites in the water source varied largely suggesting that thespatial distribution of PAEs was site specific In additionthe monitoring of PAEs in the waterworks also showed thatPAEs can be detected in the drinking water and certaintoxicological risks to drinking water consumers were foundThese results reported here contribute to an understandingof how PAE contaminants are distributed in the new watersource and the waterworks in Harbin city as well as forminga basis for further modeling risk assessment and selection ofdrinking water treatment technology

In conclusion the results implied that no urgent reme-diation measures were required with respect to PAEs in thewaters However the ecological and health effects of thesesubstances through drinkingwater at the relatively lower con-centrations still need further notice in light of their possiblebiological magnifications Therefore the long-term sourcecontrol in the water and adding advanced treatment processfor drinking water supplies should be given special attentionin this area

Acknowledgments

This work was supported by the National Natural ScienceFoundation of China (1077029) the Funds for CreativeResearch Groups of China (Grant no 51121062) the NationalNatural Science Foundation of China (51078105) and theOpen Project of the State Key Laboratory of Urban WaterResource and Environment Harbin Institute of Technology(no QA201019)

References

[1] M Nikonorow H Mazur and H Piekacz ldquoEffect of orallyadministered plasticizers and polyvinyl chloride stabilizers inthe ratrdquo Toxicology and Applied Pharmacology vol 26 no 2 pp253ndash259 1973

[2] M Vitali M Guidotti G Macilenti and C Cremisini ldquoPhtha-late esters in freshwaters asmarkers of contamination sourcesmdasha site study in ItalyrdquoEnvironment International vol 23 no 3 pp337ndash347 1997

[3] G Latini C de Felice G Presta et al ldquoIn utero exposure todi-(2-ethylhexyl)phthalate and duration of human pregnancyrdquoEnvironmental Health Perspectives vol 111 no 14 pp 1783ndash17852003

[4] C E Mackintosh J A Maldonado M G Ikonomou and F AP C Gobas ldquoSorption of phthalate esters and PCBs in a marineecosystemrdquo Environmental Science and Technology vol 40 no11 pp 3481ndash3488 2006

[5] M Clara G Windhofer W Hartl et al ldquoOccurrence of phtha-lates in surface runoff untreated and treated wastewater andfate during wastewater treatmentrdquo Chemosphere vol 78 no 9pp 1078ndash1084 2010

[6] M M Abdel Daiem J Rivera-Utrilla R Ocampo-Perez J DMendez-Dıaz andM Sanchez-Polo ldquoEnvironmental impact ofphthalic acid esters and their removal fromwater and sedimentsby different technologiesmdasha reviewrdquo Journal of EnvironmentalManagement vol 109 pp 164ndash178 2012

[7] L Chen Y Zhao L Li B Chen and Y Zhang ldquoExposureassessment of phthalates in non-occupational populations inChinardquo Science of the Total Environment vol 427-428 pp 60ndash69 2012

[8] M J Teil M Blanchard andM Chevreuil ldquoAtmospheric fate ofphthalate esters in an urban area (Paris-France)rdquo Science of theTotal Environment vol 354 no 2-3 pp 212ndash223 2006

[9] P Roslev K Vorkamp J Aarup K Frederiksen and P HNielsen ldquoDegradation of phthalate esters in an activated sludgewastewater treatment plantrdquo Water Research vol 41 no 5 pp969ndash976 2007

[10] J Gasperi S Garnaud V Rocher and R Moilleron ldquoPrioritypollutants in wastewater and combined sewer overflowrdquo Scienceof the Total Environment vol 407 no 1 pp 263ndash272 2008

[11] F Zeng K Cui Z Xie et al ldquoOccurrence of phthalate estersin water and sediment of urban lakes in a subtropical cityGuangzhou South Chinardquo Environment International vol 34no 3 pp 372ndash380 2008

[12] F Zeng K Cui Z Xie et al ldquoPhthalate esters (PAEs) emergingorganic contaminants in agricultural soils in peri-urban areasaround Guangzhou Chinardquo Environmental Pollution vol 156no 2 pp 425ndash434 2008

[13] G Wildbrett ldquoDiffusion of phthalic acid esters from PVC milktubingrdquo Environmental Health Perspectives vol 3 pp 29ndash351973

8 Journal of Analytical Methods in Chemistry

[14] H Fromme T Kuchler T Otto K Pilz J Muller and AWenzel ldquoOccurrence of phthalates and bisphenol A and F inthe environmentrdquoWater Research vol 36 no 6 pp 1429ndash14382002

[15] A D Vethaak J Lahr S M Schrap et al ldquoAn integrated assess-ment of estrogenic contamination and biological effects in theaquatic environment ofTheNetherlandsrdquoChemosphere vol 59no 4 pp 511ndash524 2005

[16] C Dargnat M Blanchard M Chevreuil andM J Teil ldquoOccur-rence of phthalate esters in the Seine River estuary (France)rdquoHydrological Processes vol 23 no 8 pp 1192ndash1201 2009

[17] T Suzuki K Yaguchi S Suzuki and T Suga ldquoMonitoring ofphthalic acid monoesters in river water by solid-phase extrac-tion and GC-MS determinationrdquo Environmental Science andTechnology vol 35 no 18 pp 3757ndash3763 2001

[18] S Y Yuan C Liu C S Liao and B V Chang ldquoOccurrenceand microbial degradation of phthalate esters in Taiwan riversedimentsrdquo Chemosphere vol 49 no 10 pp 1295ndash1299 2002

[19] B Li C Qu and J Bi ldquoIdentification of trace organic pollutantsin drinking water and the associated human health risks inJiangsu Province Chinardquo Bulletin of Environmental Contami-nation and Toxicology pp 1ndash5 2012

[20] F Wang X Xia and Y Sha ldquoDistribution of phthalic acidesters in Wuhan section of the Yangtze River Chinardquo Journalof Hazardous Materials vol 154 no 1ndash3 pp 317ndash324 2008

[21] Y J Sha X H Xia and X Q Xiao ldquoDistribution characters ofphthalic acid ester in the waters middle and lower reaches ofthe Yellow Riverrdquo China Environmental Science vol 26 no 1pp 120ndash124 2006

[22] J Lu L-B Hao C-Z Wang W Li R-J Bai and D YanldquoDistribution characteristics of phthalic acid esters in middleand lower reaches of no 2 Songhua Riverrdquo EnvironmentalScience amp Technology vol 12 article 014 2007

[23] X J Zhu and Y Y Qiu ldquoMeasuring the phthalates of xiangjiangriver using liquid-liquid extraction gas chromatographyrdquoAdvanced Materials Research vol 301 pp 752ndash755 2011

[24] B L Yuan X Z Li and N Graham ldquoAqueous oxida-tion of dimethyl phthalate in a Fe(VI)-TiO

2

-UV reaction sys-temrdquoWater Research vol 42 no 6-7 pp 1413ndash1420 2008

[25] Z Yunrui ZWanpeng L FudongW Jianbing and Y ShaoxialdquoCatalytic activity of RuAl2O3 for ozonation of dimethylphthalate in aqueous solutionrdquo Chemosphere vol 66 no 1 pp145ndash150 2007

[26] H N Gavala U Yenal and B K Ahring ldquoThermal andenzymatic pretreatment of sludge containing phthalate estersprior tomesophilic anaerobic digestionrdquoBiotechnology and Bio-engineering vol 85 no 5 pp 561ndash567 2004

[27] Y Guo Q Wu and K Kannan ldquoPhthalate metabolites in urinefrom China and implications for human exposuresrdquo Environ-ment International vol 37 no 5 pp 893ndash898 2011

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 210653 8 pageshttpdxdoiorg1011552013210653

Research ArticleSimultaneous Determination of Hormonal Residuesin Treated Waters Using Ultrahigh Performance LiquidChromatography-Tandem Mass Spectrometry

Rayco Guedes-Alonso Zoraida Sosa-Ferrera and Joseacute Juan Santana-Rodriacuteguez

Departamento de Quımica Universidad de Las Palmas de Gran Canaria 35017 Las Palmas de Gran Canaria Spain

Correspondence should be addressed to Jose Juan Santana-Rodrıguez jsantanadquiulpgces

Received 28 December 2012 Accepted 7 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Rayco Guedes-Alonso et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

In the last years hormone consumption has increased exponentially Because of that hormone compounds are considered emergingpollutants since several studies have determinted their presence in water influents and effluents of wastewater treatment plants(WWTPs) In this study a quantitative method for the simultaneous determination of oestrogens (estrone 17120573-estradiol estriol17120572-ethinylestradiol and diethylstilbestrol) androgens (testosterone) and progestogens (norgestrel andmegestrol acetate) has beendeveloped to determine these compounds in wastewater samples Due to the very low concentrations of target compounds in theenvironment a solid phase extraction procedure has been optimized and developed to extract and preconcentrate the analytesDetermination and quantification were performed by ultrahigh performance liquid chromatography-tandem mass spectrometry(UHPLC-MSMS) The method developed presents satisfactory limits of detection (between 015 and 935 ngsdotLminus1) good recoveries(between 73 and 90 for the most of compounds) and low relative standard deviations (under 84) Samples from influents andeffluents of two wastewater treatment plants of Gran Canaria (Spain) were analyzed using the proposed method finding severalhormones with concentrations ranged from 5 to 300 ngsdotLminus1

1 Introduction

In general it is supposed that more than 100000 differentchemical compounds can be introduced in the Environmentmany of them in very small quantity However a lot of thesecompounds are not included as pollutants in the legislationAlthough these compounds named emerging pollutants arenot regulated as pollutants they probably will be in the futurebecause of their potential negative effect in the ecosystem For20 years many articles have reported the presence of theseldquonew compoundsrdquo in wastewater [1 2]

The emerging pollutant origin is mainly anthropogenicconsidering that the majority of these compounds are bio-logically active substances that are synthesized to use themin agriculture industry and medicine The main source ofthese emerging pollutants is the residual urbanwaters and thewastewater treatment plants effluents because many of these

WWTPs are not designed or optimized to treat this kind ofcompounds [3]

Hormones are one of the most potent endocrine disrupt-ing compounds as well as are considered also as emergingpollutants Hormones can be differentiated in oestrogensandrogens and progestogens Some of them have limits intheir use but not a specific legislation [4]

The main characteristic of these pollutants is that it isnot necessary to remain in the environment to cause negativeeffects in view of the fact that their constant introduction init offsets their removal or degradation [5]

The steroid hormones help controlling the metabolisminflammations immunological functions water and salt bal-ance sexual development and the capacity of withstandingillnesses [6] The term steroid can be used for naturalhormones produced by the body as well as for artificiallyproduced medicines that increase the natural steroid effect

2 Journal of Analytical Methods in Chemistry

In the last 50 years the natural and synthetic hormoneworldwide consumption has grown as much as in humanmedicine as in cattle farming and they become the mostprescribed medicines [7]

A significant quantity of consumed oestrogens leaves theorganism through excretions For example 17120573-estradiol (E2)is oxidized rapidly becoming an estrone (E1) that can turninto estriol afterwards (E3) Besides the 17120572-ethinyl estradiol(EE) is excreted as conjugated [8]

With regard to emission sources in the first place arethe wastewater treatment plants (WWTPs) [9] and secon-darily cattle waste such as those leachates from dung anduncontrolled dumping [10] Several studies made in theWWTPs have reported that the treatment plants are capableof eliminating around 60 of hormones [11ndash13]

The identification of hormone residues in environmentis of special interest because knowledge of these compoundsis a requirement to take measures in order to regulate andminimize their environmental impact

However measurement of hormone residues is a verydifficult task not only due to the difficulty in measuringvery low concentration but also due to a very complexityof the samples Therefore use of mass spectrometer (MS)as detector coupled with chromatography techniques hasbecome a powerful method for the analysis of these typesof compounds at trace levels [14ndash17] Consequently LC-MSMS is the principally chosen technique One of the mainadvantages of LC-MSMS is its ability to analyze hormoneswithout derivatization (necessary in GC) or the need ofhydrolyze the conjugated form

Due to low level concentration of these compounds inenvironmental water it is necessary to apply an extractionand preconcentration method prior to LC analysis The mostused technique of extraction and preconcentration methodfor liquid samples is the solid phase extraction (SPE) [18ndash20]

The objective of this study is to develop a rapid and simpleprocedure of extraction preconcentration and determina-tion of four steroid oestrogens (estrone (E1) 17120573-estradiol(E2) estriol (E3) and 17120572-ethinylestradiol (EE)) one non-steroidal oestrogen the diethylstilbestrol (DES) one andro-gen the testosterone (TES) and two synthetic progestogensnorgestrel (NOR) and megestrol acetate (MGA) (Table 1)based on solid phase extraction and ultrahigh performanceliquid chromatography-tandem mass spectrometry (SPE-UHPLC-MSMS) The developed method was applied tothe identification and quantification of these compoundsin wastewater samples obtained from the influents andeffluents of two wastewater treatment plants (WWTPs) ofGran Canaria (Spain) They presented different methodsof wastewater treatments WWTP 1 presented a traditionalmethod based on activated sludge while WWTP 2 used amembrane bioreactor technique

2 Materials and Methods

21 Reagents All of the hormonal compounds usedwere pur-chased from Sigma-Aldrich (Madrid Spain) Stock solutionscontaining 1000mgsdotLminus1 of each analyte were prepared by

dissolving the compound inmethanol and the solutionswerestored in glass-stoppered bottles at 4∘C prior to use Workingaqueous standard solutions were prepared daily Ultrapurewater was provided by a Milli-Q system (Millipore BedfordMA USA) HPLC-grade methanol LC-MS methanol andLC-MS water as well as the ammonia and the ammoniumacetate used to adjust the pH of the mobile phases wereobtained from Panreac Quımica (Barcelona Spain)

22 Sample Collection Water samples were collected fromthe effluents of twowastewater treatment plants located in thenorthern area of Gran Canaria in May and August of 2012WWTP 1 used a conventional activated sludge treatmentsystem while WWTP 2 employed a membrane bioreactortreatment system The samples were collected in 2 L amberglass bottles that were rinsed beforehand with methanol andultrapurewater Samples were purified through filtrationwithfibreglass filters and then with 065 120583m membrane filters(Millipore Ireland) The samples were stored in the dark at4∘C and extracted within 48 hours

23 Instrumentation For the SPE optimization the instru-ment used was an ultrahigh performance liquid chromatog-raphy with fluorescence detector (UHPLC-FD) system con-sisting of an ACQUITYQuaternary Solvent Manager (QSM)used to load samples and wash and recondition the analyticalcolumn an autosampler a column manager and a fluores-cence detector with excitation and emission wavelengths of280 and 310 nm respectively all fromWaters (Madrid Spain)

The analysis of wastewater samples was performed ina UHPLC-MSMS system from Waters (Madrid Spain)similar to the described above with a 2777 autosamplerequipped with a 25120583L syringe and a tray to hold 2mLvials and an ACQUITY tandem triple quadrupole (TQD)mass spectrometer with an electrospray ionization (ESI)interface All Waters components (Madrid Spain) werecontrolled using the MassLynx Mass Spectrometry SoftwareElectrospray ionisation parameters were fixed as followsthe capillary voltage was 3 kV in positive mode and minus2 kVin negative mode the source temperature was 150∘C thedesolvation temperature was 500∘C and the desolvation gasflow rate was 1000 Lhr Nitrogen was used as the desolvationgas and argon was employed as the collision gas

The detailed MSMS detection parameters for each hor-monal compound are presented in Table 2 and were opti-mised by the direct injection of a 1mgsdotLminus1 standard solutionof each analyte into the detector at a flow rate of 10 120583Lsdotminminus1

24 Chromatographic Conditions For the SPE optimizationthe analytical column was a 50mm times 21mm ACQUITYUHPLCBEHWaters C

18columnwith a particle size of 17120583m

(Waters Chromatography Barcelona Spain) operating at atemperature of 30∘C Analytes separation was carried outemploying the following gradient starting at 55 45 (vv)water methanol for 1 minute During 3 minutes it changedto 50 50 (vv) and stayed for 25 minutes more Finally cameback to initial conditions in 1 minute and stayed for 15

Journal of Analytical Methods in Chemistry 3

Table 1 List of hormonal compounds pKa values chemical structure and retention times

Compound pKa [21] Structure 119905119877

(min)

E3 Estriol 103

HO

OH

OH

H H

H096

E2 17120573-estradiol 103

HO

OH

H H

H218

EE 17120572-ethinylestradiol 103

HO

HO

H H

H223

E1 Estrone 103

HO

O

H

H H220

DES Diethylstilbestrol 102

HO

OH

235

TES Testosterone 151

OH

OH H

H240

MGA Megestrol acetate

O

O

O

OH

H

H306

NOR Levonorgestrel 131

OH

O

H

H

H

H263

minutes Therefore the analysis took 9 minutes at a flow of05mLsdotminminus1

For the analysis of real samples aUHPLC-MSMS systemwas used The analytical column was the same and themobile phase was water and methanol adjusted with a bufferconsisting in 01 vv ammonia and 15mM of ammoniumacetate The analysis was performed in gradient mode at aflow rate of 03mLsdotminminus1The gradient started at 50 50 (vv)mixture of water methanol which changed to 25 75 (vv) in3 minutes and returned to 50 50 in 1 minute more Finallythe gradient stayed calibrating for another 15 minutes moreThe sample volume injected was 5120583L

3 Results and Discussion

31 Optimization of Solid-Phase Extraction (SPE) There area number of parameters that affect SPE procedure such as

type of sorbent pH ionic strength sample and desorptionvolumes and wash step To optimize these parameters itused Milli-Q water spiked with a solution of fluorescenceoestrogens (estriol 17120573-estradiol and 17120572-ethinylestradiol)to obtain a final concentration of 250120583gsdotLminus1

The first parameter to optimize is the choice of sorbentsince it controls the selectivity affinity and capacity overanalytes In this study the SPE cartridges used were OASISHLB SepPak C

18(both from Waters Madrid Spain) and

BondElut ENV (fromAgilent Madrid Spain) Keeping otherparameters fixed (ionic strength of 0 sample volume of100mL) the cartridges were studied at three different pHs(5 8 and 11) From the results obtained it can be observedthat the better signals are found for SepPak C

18cartridge

(Figure 1)After choosing the optimum cartridge we used an initial

experimental design of 23 to study the influence of pH ionic

4 Journal of Analytical Methods in Chemistry

Table 2 Mass spectrometer parameters for the determination of target analytes

Compound Precursor ion(mz)

Capillary voltage(Ion mode)

Quantification ionmz(collision potential V)

Quantification ionmz(collision potential V)

E3 2872 minus65V (ESI minus) 1710 (37) 1452 (39)E2 2712 minus65V (ESI minus) 1451 (40) 1831 (31)EE 2952 minus60V (ESI minus) 1450 (37) 1589 (33)E1 2692 minus65V (ESI minus) 1450 (36) 1430 (48)DES 2671 minus50V (ESI minus) 2371 (29) 2511 (25)TES 2892 38V (ESI +) 1870 (18) 1040 (21)MGA 3855 30V (ESI +) 2673 (15) 2242 (30)NOR 3132 38V (ESI +) 1090 (26) 2451 (18)

0

500

1000

1500

2000

2500

E3 E2 EE

Peak

area

Cartridge optimizationOASIS HLB pH = 5

OASIS HLB pH = 8

OASIS HLB pH = 11SepPak C18 pH = 5

SepPak C18 pH = 8

SepPak C18 pH = 11BondElut ENV pH = 5

BondElut ENV pH = 8

BondElut ENV pH =11

Figure 1 Optimization of SPE cartridges

strength and sample volume over extraction process Theexperimental design was obtained using Statgraphics Plussoftware 51 and the statistics study was done with IBM SPSSStatistics 19 We assessed two levels and three parameters pH(3 and 8) ionic strength (0 and 30 of NaCl) and samplevolume (50 and 250mL) to obtain the influence of eachparameter and the variable correlation to each other In thisstudy it is observed that the ionic strength and sample volumehad the major influence on the recoveries of the analytesFor that a 32 factorial design to optimize these two variablesat three levels per parameter (0 15 and 30 of NaCl forionic strength and 50 100 y 250mL for sample volume) wasused Figure 2 shows the response surface obtained for theestriol and 17120572-ethinylestradiol The results obtained showedthat an increment of the ionic strength did not producean increase in the response area of the compound and theoptimum volume was 250mL Because of that a solutionwithout salt addition and 250mL of sample volume waschosen Finally the desorption volume (1mLofmethanol and2mL of methanol in one and two steps) and wash-step (5mL

ofMilli-Q water and 5mL ofMilli-Q water with 5 and 10 ofmethanol vv) were assayed to complete the optimization ofthe SPE process The optimum values were 2mL of methanolin one step and 5mL of Milli-Q water without methanolrespectively

In accordance with the obtained results the optimumconditions for SPE procedure were SepPak C

18cartridge

250mL of sample at pH = 8 and 0 of NaCl desorptionwith 2mL of methanol in one step and wash step with5mL of Milli-Q water In these conditions we achieved apreconcentration factor of 125 In Figure 3 a chromatogramwith the optimum conditions is shown where the peaksof all compounds in their corresponding transitions can beobserved

32 Analytical Parameters Because of the SPE optimizationthat was done only with fluorescent compounds (estriol 17120573-estradiol and 17120572-ethinylestradiol) it was necessary to studythe recoveries of all the hormonal compounds using theoptimized SPE-UHPLC-MSMSmethod All the compoundsunder study showed good recoveries over 73 except thediethylstilbestrol with a recovery of 507

A calibration curve was used for the quantification ofthe analytes by diluting the stock solution of each analyteinto the samples to concentrations ranging between 1 and100 120583gsdotLminus1 Analysis was conducted by UHPLC-MSMS andlinear calibration plots for each analyte (1199032 gt 099) wereobtained based on their chromatographic peak areas

The limit of detection (LOD) and the limit of quantifi-cation (LOQ) for each compound were calculated from thesignal-to-noise ratio of each individual peak The LOD wasdefined as the lowest concentration that gave a signal-to-noiseratio that was greater than 3 The LOQ was defined as thelowest concentration that gave a signal to noise ratio that wasgreater than 10The LODs ranged from015 to 935 ngsdotLminus1 andthe LOQs ranged from 049 to 3118 ngsdotLminus1

The performance and reliability of the process werestudied by determining the repeatability of the quantificationresults for all target analytes under the described conditionsusing six samples (119899 = 6) The relative standard deviations(RSDs) were lower than 84 in all cases indicating a

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 14: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Journal of Analytical Methods in Chemistry 7

DEHP in drinkingwater samples from theMPSWwere lowerthan the limited value

PAEs are also considered to be endocrine disruptingchemicals (EDCs) whose effects may not appear until long-term exposure According to the results PAEs were detectedin the drinking water constantly ingested in daily life indi-cating that drinking water is an important source of humanexposure to PAEs contaminants Assuming a daily waterconsumption rate of 2 L and an average body weight of 60 kgfor adults the average daily intake of DEHP DBP and DIBPby way of drinking water from MPSW was calculated to be1158 1352 and 81 ngkgd respectively In comparison thevalues of SW with the water source of the Songhua Riverwere relatively higher with the calculated results of 1353140 and 155 ngkgd for DEHP DBP and DIBP respectivelyIn this study the estimated daily intake levels of DEHPfrom the drinking water were quite lower than the RfDof 20000 ngkgd released by the EPA However some ofPAEs are partly metabolised in the organism and futureexperiments should be focused on determining the potentialeffects of the metabolites [27]

Currently treated water from the Songhua River is fornonpotable uses and MPSW is the exclusive waterworks runfor the water supply of Harbin city However populationgrowth and drought cycle are limited by the availability of rawwater from theMopanshan Reservoir Tomeet the increasingdemand local and regional water authorities have begun acampaign of second water supply project from the SonghuaRiver again which needs the protection of the Songhua Riverand advanced water treatment for the source

4 Conclusions

This study provided the first detailed data on the contami-nation status of 15 PAEs in the water near the MopanshanReservoir The concentration range of 15 PAEs in the sampleswas from 3558 to 92265 ngL with the mean value of29431 ngL DEHP andDBPwere themain pollutants among15 PAEs accounting for the main watershed pollution Theoccurrence and distribution of PAEs from different samplingsites in the water source varied largely suggesting that thespatial distribution of PAEs was site specific In additionthe monitoring of PAEs in the waterworks also showed thatPAEs can be detected in the drinking water and certaintoxicological risks to drinking water consumers were foundThese results reported here contribute to an understandingof how PAE contaminants are distributed in the new watersource and the waterworks in Harbin city as well as forminga basis for further modeling risk assessment and selection ofdrinking water treatment technology

In conclusion the results implied that no urgent reme-diation measures were required with respect to PAEs in thewaters However the ecological and health effects of thesesubstances through drinkingwater at the relatively lower con-centrations still need further notice in light of their possiblebiological magnifications Therefore the long-term sourcecontrol in the water and adding advanced treatment processfor drinking water supplies should be given special attentionin this area

Acknowledgments

This work was supported by the National Natural ScienceFoundation of China (1077029) the Funds for CreativeResearch Groups of China (Grant no 51121062) the NationalNatural Science Foundation of China (51078105) and theOpen Project of the State Key Laboratory of Urban WaterResource and Environment Harbin Institute of Technology(no QA201019)

References

[1] M Nikonorow H Mazur and H Piekacz ldquoEffect of orallyadministered plasticizers and polyvinyl chloride stabilizers inthe ratrdquo Toxicology and Applied Pharmacology vol 26 no 2 pp253ndash259 1973

[2] M Vitali M Guidotti G Macilenti and C Cremisini ldquoPhtha-late esters in freshwaters asmarkers of contamination sourcesmdasha site study in ItalyrdquoEnvironment International vol 23 no 3 pp337ndash347 1997

[3] G Latini C de Felice G Presta et al ldquoIn utero exposure todi-(2-ethylhexyl)phthalate and duration of human pregnancyrdquoEnvironmental Health Perspectives vol 111 no 14 pp 1783ndash17852003

[4] C E Mackintosh J A Maldonado M G Ikonomou and F AP C Gobas ldquoSorption of phthalate esters and PCBs in a marineecosystemrdquo Environmental Science and Technology vol 40 no11 pp 3481ndash3488 2006

[5] M Clara G Windhofer W Hartl et al ldquoOccurrence of phtha-lates in surface runoff untreated and treated wastewater andfate during wastewater treatmentrdquo Chemosphere vol 78 no 9pp 1078ndash1084 2010

[6] M M Abdel Daiem J Rivera-Utrilla R Ocampo-Perez J DMendez-Dıaz andM Sanchez-Polo ldquoEnvironmental impact ofphthalic acid esters and their removal fromwater and sedimentsby different technologiesmdasha reviewrdquo Journal of EnvironmentalManagement vol 109 pp 164ndash178 2012

[7] L Chen Y Zhao L Li B Chen and Y Zhang ldquoExposureassessment of phthalates in non-occupational populations inChinardquo Science of the Total Environment vol 427-428 pp 60ndash69 2012

[8] M J Teil M Blanchard andM Chevreuil ldquoAtmospheric fate ofphthalate esters in an urban area (Paris-France)rdquo Science of theTotal Environment vol 354 no 2-3 pp 212ndash223 2006

[9] P Roslev K Vorkamp J Aarup K Frederiksen and P HNielsen ldquoDegradation of phthalate esters in an activated sludgewastewater treatment plantrdquo Water Research vol 41 no 5 pp969ndash976 2007

[10] J Gasperi S Garnaud V Rocher and R Moilleron ldquoPrioritypollutants in wastewater and combined sewer overflowrdquo Scienceof the Total Environment vol 407 no 1 pp 263ndash272 2008

[11] F Zeng K Cui Z Xie et al ldquoOccurrence of phthalate estersin water and sediment of urban lakes in a subtropical cityGuangzhou South Chinardquo Environment International vol 34no 3 pp 372ndash380 2008

[12] F Zeng K Cui Z Xie et al ldquoPhthalate esters (PAEs) emergingorganic contaminants in agricultural soils in peri-urban areasaround Guangzhou Chinardquo Environmental Pollution vol 156no 2 pp 425ndash434 2008

[13] G Wildbrett ldquoDiffusion of phthalic acid esters from PVC milktubingrdquo Environmental Health Perspectives vol 3 pp 29ndash351973

8 Journal of Analytical Methods in Chemistry

[14] H Fromme T Kuchler T Otto K Pilz J Muller and AWenzel ldquoOccurrence of phthalates and bisphenol A and F inthe environmentrdquoWater Research vol 36 no 6 pp 1429ndash14382002

[15] A D Vethaak J Lahr S M Schrap et al ldquoAn integrated assess-ment of estrogenic contamination and biological effects in theaquatic environment ofTheNetherlandsrdquoChemosphere vol 59no 4 pp 511ndash524 2005

[16] C Dargnat M Blanchard M Chevreuil andM J Teil ldquoOccur-rence of phthalate esters in the Seine River estuary (France)rdquoHydrological Processes vol 23 no 8 pp 1192ndash1201 2009

[17] T Suzuki K Yaguchi S Suzuki and T Suga ldquoMonitoring ofphthalic acid monoesters in river water by solid-phase extrac-tion and GC-MS determinationrdquo Environmental Science andTechnology vol 35 no 18 pp 3757ndash3763 2001

[18] S Y Yuan C Liu C S Liao and B V Chang ldquoOccurrenceand microbial degradation of phthalate esters in Taiwan riversedimentsrdquo Chemosphere vol 49 no 10 pp 1295ndash1299 2002

[19] B Li C Qu and J Bi ldquoIdentification of trace organic pollutantsin drinking water and the associated human health risks inJiangsu Province Chinardquo Bulletin of Environmental Contami-nation and Toxicology pp 1ndash5 2012

[20] F Wang X Xia and Y Sha ldquoDistribution of phthalic acidesters in Wuhan section of the Yangtze River Chinardquo Journalof Hazardous Materials vol 154 no 1ndash3 pp 317ndash324 2008

[21] Y J Sha X H Xia and X Q Xiao ldquoDistribution characters ofphthalic acid ester in the waters middle and lower reaches ofthe Yellow Riverrdquo China Environmental Science vol 26 no 1pp 120ndash124 2006

[22] J Lu L-B Hao C-Z Wang W Li R-J Bai and D YanldquoDistribution characteristics of phthalic acid esters in middleand lower reaches of no 2 Songhua Riverrdquo EnvironmentalScience amp Technology vol 12 article 014 2007

[23] X J Zhu and Y Y Qiu ldquoMeasuring the phthalates of xiangjiangriver using liquid-liquid extraction gas chromatographyrdquoAdvanced Materials Research vol 301 pp 752ndash755 2011

[24] B L Yuan X Z Li and N Graham ldquoAqueous oxida-tion of dimethyl phthalate in a Fe(VI)-TiO

2

-UV reaction sys-temrdquoWater Research vol 42 no 6-7 pp 1413ndash1420 2008

[25] Z Yunrui ZWanpeng L FudongW Jianbing and Y ShaoxialdquoCatalytic activity of RuAl2O3 for ozonation of dimethylphthalate in aqueous solutionrdquo Chemosphere vol 66 no 1 pp145ndash150 2007

[26] H N Gavala U Yenal and B K Ahring ldquoThermal andenzymatic pretreatment of sludge containing phthalate estersprior tomesophilic anaerobic digestionrdquoBiotechnology and Bio-engineering vol 85 no 5 pp 561ndash567 2004

[27] Y Guo Q Wu and K Kannan ldquoPhthalate metabolites in urinefrom China and implications for human exposuresrdquo Environ-ment International vol 37 no 5 pp 893ndash898 2011

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 210653 8 pageshttpdxdoiorg1011552013210653

Research ArticleSimultaneous Determination of Hormonal Residuesin Treated Waters Using Ultrahigh Performance LiquidChromatography-Tandem Mass Spectrometry

Rayco Guedes-Alonso Zoraida Sosa-Ferrera and Joseacute Juan Santana-Rodriacuteguez

Departamento de Quımica Universidad de Las Palmas de Gran Canaria 35017 Las Palmas de Gran Canaria Spain

Correspondence should be addressed to Jose Juan Santana-Rodrıguez jsantanadquiulpgces

Received 28 December 2012 Accepted 7 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Rayco Guedes-Alonso et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

In the last years hormone consumption has increased exponentially Because of that hormone compounds are considered emergingpollutants since several studies have determinted their presence in water influents and effluents of wastewater treatment plants(WWTPs) In this study a quantitative method for the simultaneous determination of oestrogens (estrone 17120573-estradiol estriol17120572-ethinylestradiol and diethylstilbestrol) androgens (testosterone) and progestogens (norgestrel andmegestrol acetate) has beendeveloped to determine these compounds in wastewater samples Due to the very low concentrations of target compounds in theenvironment a solid phase extraction procedure has been optimized and developed to extract and preconcentrate the analytesDetermination and quantification were performed by ultrahigh performance liquid chromatography-tandem mass spectrometry(UHPLC-MSMS) The method developed presents satisfactory limits of detection (between 015 and 935 ngsdotLminus1) good recoveries(between 73 and 90 for the most of compounds) and low relative standard deviations (under 84) Samples from influents andeffluents of two wastewater treatment plants of Gran Canaria (Spain) were analyzed using the proposed method finding severalhormones with concentrations ranged from 5 to 300 ngsdotLminus1

1 Introduction

In general it is supposed that more than 100000 differentchemical compounds can be introduced in the Environmentmany of them in very small quantity However a lot of thesecompounds are not included as pollutants in the legislationAlthough these compounds named emerging pollutants arenot regulated as pollutants they probably will be in the futurebecause of their potential negative effect in the ecosystem For20 years many articles have reported the presence of theseldquonew compoundsrdquo in wastewater [1 2]

The emerging pollutant origin is mainly anthropogenicconsidering that the majority of these compounds are bio-logically active substances that are synthesized to use themin agriculture industry and medicine The main source ofthese emerging pollutants is the residual urbanwaters and thewastewater treatment plants effluents because many of these

WWTPs are not designed or optimized to treat this kind ofcompounds [3]

Hormones are one of the most potent endocrine disrupt-ing compounds as well as are considered also as emergingpollutants Hormones can be differentiated in oestrogensandrogens and progestogens Some of them have limits intheir use but not a specific legislation [4]

The main characteristic of these pollutants is that it isnot necessary to remain in the environment to cause negativeeffects in view of the fact that their constant introduction init offsets their removal or degradation [5]

The steroid hormones help controlling the metabolisminflammations immunological functions water and salt bal-ance sexual development and the capacity of withstandingillnesses [6] The term steroid can be used for naturalhormones produced by the body as well as for artificiallyproduced medicines that increase the natural steroid effect

2 Journal of Analytical Methods in Chemistry

In the last 50 years the natural and synthetic hormoneworldwide consumption has grown as much as in humanmedicine as in cattle farming and they become the mostprescribed medicines [7]

A significant quantity of consumed oestrogens leaves theorganism through excretions For example 17120573-estradiol (E2)is oxidized rapidly becoming an estrone (E1) that can turninto estriol afterwards (E3) Besides the 17120572-ethinyl estradiol(EE) is excreted as conjugated [8]

With regard to emission sources in the first place arethe wastewater treatment plants (WWTPs) [9] and secon-darily cattle waste such as those leachates from dung anduncontrolled dumping [10] Several studies made in theWWTPs have reported that the treatment plants are capableof eliminating around 60 of hormones [11ndash13]

The identification of hormone residues in environmentis of special interest because knowledge of these compoundsis a requirement to take measures in order to regulate andminimize their environmental impact

However measurement of hormone residues is a verydifficult task not only due to the difficulty in measuringvery low concentration but also due to a very complexityof the samples Therefore use of mass spectrometer (MS)as detector coupled with chromatography techniques hasbecome a powerful method for the analysis of these typesof compounds at trace levels [14ndash17] Consequently LC-MSMS is the principally chosen technique One of the mainadvantages of LC-MSMS is its ability to analyze hormoneswithout derivatization (necessary in GC) or the need ofhydrolyze the conjugated form

Due to low level concentration of these compounds inenvironmental water it is necessary to apply an extractionand preconcentration method prior to LC analysis The mostused technique of extraction and preconcentration methodfor liquid samples is the solid phase extraction (SPE) [18ndash20]

The objective of this study is to develop a rapid and simpleprocedure of extraction preconcentration and determina-tion of four steroid oestrogens (estrone (E1) 17120573-estradiol(E2) estriol (E3) and 17120572-ethinylestradiol (EE)) one non-steroidal oestrogen the diethylstilbestrol (DES) one andro-gen the testosterone (TES) and two synthetic progestogensnorgestrel (NOR) and megestrol acetate (MGA) (Table 1)based on solid phase extraction and ultrahigh performanceliquid chromatography-tandem mass spectrometry (SPE-UHPLC-MSMS) The developed method was applied tothe identification and quantification of these compoundsin wastewater samples obtained from the influents andeffluents of two wastewater treatment plants (WWTPs) ofGran Canaria (Spain) They presented different methodsof wastewater treatments WWTP 1 presented a traditionalmethod based on activated sludge while WWTP 2 used amembrane bioreactor technique

2 Materials and Methods

21 Reagents All of the hormonal compounds usedwere pur-chased from Sigma-Aldrich (Madrid Spain) Stock solutionscontaining 1000mgsdotLminus1 of each analyte were prepared by

dissolving the compound inmethanol and the solutionswerestored in glass-stoppered bottles at 4∘C prior to use Workingaqueous standard solutions were prepared daily Ultrapurewater was provided by a Milli-Q system (Millipore BedfordMA USA) HPLC-grade methanol LC-MS methanol andLC-MS water as well as the ammonia and the ammoniumacetate used to adjust the pH of the mobile phases wereobtained from Panreac Quımica (Barcelona Spain)

22 Sample Collection Water samples were collected fromthe effluents of twowastewater treatment plants located in thenorthern area of Gran Canaria in May and August of 2012WWTP 1 used a conventional activated sludge treatmentsystem while WWTP 2 employed a membrane bioreactortreatment system The samples were collected in 2 L amberglass bottles that were rinsed beforehand with methanol andultrapurewater Samples were purified through filtrationwithfibreglass filters and then with 065 120583m membrane filters(Millipore Ireland) The samples were stored in the dark at4∘C and extracted within 48 hours

23 Instrumentation For the SPE optimization the instru-ment used was an ultrahigh performance liquid chromatog-raphy with fluorescence detector (UHPLC-FD) system con-sisting of an ACQUITYQuaternary Solvent Manager (QSM)used to load samples and wash and recondition the analyticalcolumn an autosampler a column manager and a fluores-cence detector with excitation and emission wavelengths of280 and 310 nm respectively all fromWaters (Madrid Spain)

The analysis of wastewater samples was performed ina UHPLC-MSMS system from Waters (Madrid Spain)similar to the described above with a 2777 autosamplerequipped with a 25120583L syringe and a tray to hold 2mLvials and an ACQUITY tandem triple quadrupole (TQD)mass spectrometer with an electrospray ionization (ESI)interface All Waters components (Madrid Spain) werecontrolled using the MassLynx Mass Spectrometry SoftwareElectrospray ionisation parameters were fixed as followsthe capillary voltage was 3 kV in positive mode and minus2 kVin negative mode the source temperature was 150∘C thedesolvation temperature was 500∘C and the desolvation gasflow rate was 1000 Lhr Nitrogen was used as the desolvationgas and argon was employed as the collision gas

The detailed MSMS detection parameters for each hor-monal compound are presented in Table 2 and were opti-mised by the direct injection of a 1mgsdotLminus1 standard solutionof each analyte into the detector at a flow rate of 10 120583Lsdotminminus1

24 Chromatographic Conditions For the SPE optimizationthe analytical column was a 50mm times 21mm ACQUITYUHPLCBEHWaters C

18columnwith a particle size of 17120583m

(Waters Chromatography Barcelona Spain) operating at atemperature of 30∘C Analytes separation was carried outemploying the following gradient starting at 55 45 (vv)water methanol for 1 minute During 3 minutes it changedto 50 50 (vv) and stayed for 25 minutes more Finally cameback to initial conditions in 1 minute and stayed for 15

Journal of Analytical Methods in Chemistry 3

Table 1 List of hormonal compounds pKa values chemical structure and retention times

Compound pKa [21] Structure 119905119877

(min)

E3 Estriol 103

HO

OH

OH

H H

H096

E2 17120573-estradiol 103

HO

OH

H H

H218

EE 17120572-ethinylestradiol 103

HO

HO

H H

H223

E1 Estrone 103

HO

O

H

H H220

DES Diethylstilbestrol 102

HO

OH

235

TES Testosterone 151

OH

OH H

H240

MGA Megestrol acetate

O

O

O

OH

H

H306

NOR Levonorgestrel 131

OH

O

H

H

H

H263

minutes Therefore the analysis took 9 minutes at a flow of05mLsdotminminus1

For the analysis of real samples aUHPLC-MSMS systemwas used The analytical column was the same and themobile phase was water and methanol adjusted with a bufferconsisting in 01 vv ammonia and 15mM of ammoniumacetate The analysis was performed in gradient mode at aflow rate of 03mLsdotminminus1The gradient started at 50 50 (vv)mixture of water methanol which changed to 25 75 (vv) in3 minutes and returned to 50 50 in 1 minute more Finallythe gradient stayed calibrating for another 15 minutes moreThe sample volume injected was 5120583L

3 Results and Discussion

31 Optimization of Solid-Phase Extraction (SPE) There area number of parameters that affect SPE procedure such as

type of sorbent pH ionic strength sample and desorptionvolumes and wash step To optimize these parameters itused Milli-Q water spiked with a solution of fluorescenceoestrogens (estriol 17120573-estradiol and 17120572-ethinylestradiol)to obtain a final concentration of 250120583gsdotLminus1

The first parameter to optimize is the choice of sorbentsince it controls the selectivity affinity and capacity overanalytes In this study the SPE cartridges used were OASISHLB SepPak C

18(both from Waters Madrid Spain) and

BondElut ENV (fromAgilent Madrid Spain) Keeping otherparameters fixed (ionic strength of 0 sample volume of100mL) the cartridges were studied at three different pHs(5 8 and 11) From the results obtained it can be observedthat the better signals are found for SepPak C

18cartridge

(Figure 1)After choosing the optimum cartridge we used an initial

experimental design of 23 to study the influence of pH ionic

4 Journal of Analytical Methods in Chemistry

Table 2 Mass spectrometer parameters for the determination of target analytes

Compound Precursor ion(mz)

Capillary voltage(Ion mode)

Quantification ionmz(collision potential V)

Quantification ionmz(collision potential V)

E3 2872 minus65V (ESI minus) 1710 (37) 1452 (39)E2 2712 minus65V (ESI minus) 1451 (40) 1831 (31)EE 2952 minus60V (ESI minus) 1450 (37) 1589 (33)E1 2692 minus65V (ESI minus) 1450 (36) 1430 (48)DES 2671 minus50V (ESI minus) 2371 (29) 2511 (25)TES 2892 38V (ESI +) 1870 (18) 1040 (21)MGA 3855 30V (ESI +) 2673 (15) 2242 (30)NOR 3132 38V (ESI +) 1090 (26) 2451 (18)

0

500

1000

1500

2000

2500

E3 E2 EE

Peak

area

Cartridge optimizationOASIS HLB pH = 5

OASIS HLB pH = 8

OASIS HLB pH = 11SepPak C18 pH = 5

SepPak C18 pH = 8

SepPak C18 pH = 11BondElut ENV pH = 5

BondElut ENV pH = 8

BondElut ENV pH =11

Figure 1 Optimization of SPE cartridges

strength and sample volume over extraction process Theexperimental design was obtained using Statgraphics Plussoftware 51 and the statistics study was done with IBM SPSSStatistics 19 We assessed two levels and three parameters pH(3 and 8) ionic strength (0 and 30 of NaCl) and samplevolume (50 and 250mL) to obtain the influence of eachparameter and the variable correlation to each other In thisstudy it is observed that the ionic strength and sample volumehad the major influence on the recoveries of the analytesFor that a 32 factorial design to optimize these two variablesat three levels per parameter (0 15 and 30 of NaCl forionic strength and 50 100 y 250mL for sample volume) wasused Figure 2 shows the response surface obtained for theestriol and 17120572-ethinylestradiol The results obtained showedthat an increment of the ionic strength did not producean increase in the response area of the compound and theoptimum volume was 250mL Because of that a solutionwithout salt addition and 250mL of sample volume waschosen Finally the desorption volume (1mLofmethanol and2mL of methanol in one and two steps) and wash-step (5mL

ofMilli-Q water and 5mL ofMilli-Q water with 5 and 10 ofmethanol vv) were assayed to complete the optimization ofthe SPE process The optimum values were 2mL of methanolin one step and 5mL of Milli-Q water without methanolrespectively

In accordance with the obtained results the optimumconditions for SPE procedure were SepPak C

18cartridge

250mL of sample at pH = 8 and 0 of NaCl desorptionwith 2mL of methanol in one step and wash step with5mL of Milli-Q water In these conditions we achieved apreconcentration factor of 125 In Figure 3 a chromatogramwith the optimum conditions is shown where the peaksof all compounds in their corresponding transitions can beobserved

32 Analytical Parameters Because of the SPE optimizationthat was done only with fluorescent compounds (estriol 17120573-estradiol and 17120572-ethinylestradiol) it was necessary to studythe recoveries of all the hormonal compounds using theoptimized SPE-UHPLC-MSMSmethod All the compoundsunder study showed good recoveries over 73 except thediethylstilbestrol with a recovery of 507

A calibration curve was used for the quantification ofthe analytes by diluting the stock solution of each analyteinto the samples to concentrations ranging between 1 and100 120583gsdotLminus1 Analysis was conducted by UHPLC-MSMS andlinear calibration plots for each analyte (1199032 gt 099) wereobtained based on their chromatographic peak areas

The limit of detection (LOD) and the limit of quantifi-cation (LOQ) for each compound were calculated from thesignal-to-noise ratio of each individual peak The LOD wasdefined as the lowest concentration that gave a signal-to-noiseratio that was greater than 3 The LOQ was defined as thelowest concentration that gave a signal to noise ratio that wasgreater than 10The LODs ranged from015 to 935 ngsdotLminus1 andthe LOQs ranged from 049 to 3118 ngsdotLminus1

The performance and reliability of the process werestudied by determining the repeatability of the quantificationresults for all target analytes under the described conditionsusing six samples (119899 = 6) The relative standard deviations(RSDs) were lower than 84 in all cases indicating a

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 15: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

8 Journal of Analytical Methods in Chemistry

[14] H Fromme T Kuchler T Otto K Pilz J Muller and AWenzel ldquoOccurrence of phthalates and bisphenol A and F inthe environmentrdquoWater Research vol 36 no 6 pp 1429ndash14382002

[15] A D Vethaak J Lahr S M Schrap et al ldquoAn integrated assess-ment of estrogenic contamination and biological effects in theaquatic environment ofTheNetherlandsrdquoChemosphere vol 59no 4 pp 511ndash524 2005

[16] C Dargnat M Blanchard M Chevreuil andM J Teil ldquoOccur-rence of phthalate esters in the Seine River estuary (France)rdquoHydrological Processes vol 23 no 8 pp 1192ndash1201 2009

[17] T Suzuki K Yaguchi S Suzuki and T Suga ldquoMonitoring ofphthalic acid monoesters in river water by solid-phase extrac-tion and GC-MS determinationrdquo Environmental Science andTechnology vol 35 no 18 pp 3757ndash3763 2001

[18] S Y Yuan C Liu C S Liao and B V Chang ldquoOccurrenceand microbial degradation of phthalate esters in Taiwan riversedimentsrdquo Chemosphere vol 49 no 10 pp 1295ndash1299 2002

[19] B Li C Qu and J Bi ldquoIdentification of trace organic pollutantsin drinking water and the associated human health risks inJiangsu Province Chinardquo Bulletin of Environmental Contami-nation and Toxicology pp 1ndash5 2012

[20] F Wang X Xia and Y Sha ldquoDistribution of phthalic acidesters in Wuhan section of the Yangtze River Chinardquo Journalof Hazardous Materials vol 154 no 1ndash3 pp 317ndash324 2008

[21] Y J Sha X H Xia and X Q Xiao ldquoDistribution characters ofphthalic acid ester in the waters middle and lower reaches ofthe Yellow Riverrdquo China Environmental Science vol 26 no 1pp 120ndash124 2006

[22] J Lu L-B Hao C-Z Wang W Li R-J Bai and D YanldquoDistribution characteristics of phthalic acid esters in middleand lower reaches of no 2 Songhua Riverrdquo EnvironmentalScience amp Technology vol 12 article 014 2007

[23] X J Zhu and Y Y Qiu ldquoMeasuring the phthalates of xiangjiangriver using liquid-liquid extraction gas chromatographyrdquoAdvanced Materials Research vol 301 pp 752ndash755 2011

[24] B L Yuan X Z Li and N Graham ldquoAqueous oxida-tion of dimethyl phthalate in a Fe(VI)-TiO

2

-UV reaction sys-temrdquoWater Research vol 42 no 6-7 pp 1413ndash1420 2008

[25] Z Yunrui ZWanpeng L FudongW Jianbing and Y ShaoxialdquoCatalytic activity of RuAl2O3 for ozonation of dimethylphthalate in aqueous solutionrdquo Chemosphere vol 66 no 1 pp145ndash150 2007

[26] H N Gavala U Yenal and B K Ahring ldquoThermal andenzymatic pretreatment of sludge containing phthalate estersprior tomesophilic anaerobic digestionrdquoBiotechnology and Bio-engineering vol 85 no 5 pp 561ndash567 2004

[27] Y Guo Q Wu and K Kannan ldquoPhthalate metabolites in urinefrom China and implications for human exposuresrdquo Environ-ment International vol 37 no 5 pp 893ndash898 2011

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 210653 8 pageshttpdxdoiorg1011552013210653

Research ArticleSimultaneous Determination of Hormonal Residuesin Treated Waters Using Ultrahigh Performance LiquidChromatography-Tandem Mass Spectrometry

Rayco Guedes-Alonso Zoraida Sosa-Ferrera and Joseacute Juan Santana-Rodriacuteguez

Departamento de Quımica Universidad de Las Palmas de Gran Canaria 35017 Las Palmas de Gran Canaria Spain

Correspondence should be addressed to Jose Juan Santana-Rodrıguez jsantanadquiulpgces

Received 28 December 2012 Accepted 7 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Rayco Guedes-Alonso et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

In the last years hormone consumption has increased exponentially Because of that hormone compounds are considered emergingpollutants since several studies have determinted their presence in water influents and effluents of wastewater treatment plants(WWTPs) In this study a quantitative method for the simultaneous determination of oestrogens (estrone 17120573-estradiol estriol17120572-ethinylestradiol and diethylstilbestrol) androgens (testosterone) and progestogens (norgestrel andmegestrol acetate) has beendeveloped to determine these compounds in wastewater samples Due to the very low concentrations of target compounds in theenvironment a solid phase extraction procedure has been optimized and developed to extract and preconcentrate the analytesDetermination and quantification were performed by ultrahigh performance liquid chromatography-tandem mass spectrometry(UHPLC-MSMS) The method developed presents satisfactory limits of detection (between 015 and 935 ngsdotLminus1) good recoveries(between 73 and 90 for the most of compounds) and low relative standard deviations (under 84) Samples from influents andeffluents of two wastewater treatment plants of Gran Canaria (Spain) were analyzed using the proposed method finding severalhormones with concentrations ranged from 5 to 300 ngsdotLminus1

1 Introduction

In general it is supposed that more than 100000 differentchemical compounds can be introduced in the Environmentmany of them in very small quantity However a lot of thesecompounds are not included as pollutants in the legislationAlthough these compounds named emerging pollutants arenot regulated as pollutants they probably will be in the futurebecause of their potential negative effect in the ecosystem For20 years many articles have reported the presence of theseldquonew compoundsrdquo in wastewater [1 2]

The emerging pollutant origin is mainly anthropogenicconsidering that the majority of these compounds are bio-logically active substances that are synthesized to use themin agriculture industry and medicine The main source ofthese emerging pollutants is the residual urbanwaters and thewastewater treatment plants effluents because many of these

WWTPs are not designed or optimized to treat this kind ofcompounds [3]

Hormones are one of the most potent endocrine disrupt-ing compounds as well as are considered also as emergingpollutants Hormones can be differentiated in oestrogensandrogens and progestogens Some of them have limits intheir use but not a specific legislation [4]

The main characteristic of these pollutants is that it isnot necessary to remain in the environment to cause negativeeffects in view of the fact that their constant introduction init offsets their removal or degradation [5]

The steroid hormones help controlling the metabolisminflammations immunological functions water and salt bal-ance sexual development and the capacity of withstandingillnesses [6] The term steroid can be used for naturalhormones produced by the body as well as for artificiallyproduced medicines that increase the natural steroid effect

2 Journal of Analytical Methods in Chemistry

In the last 50 years the natural and synthetic hormoneworldwide consumption has grown as much as in humanmedicine as in cattle farming and they become the mostprescribed medicines [7]

A significant quantity of consumed oestrogens leaves theorganism through excretions For example 17120573-estradiol (E2)is oxidized rapidly becoming an estrone (E1) that can turninto estriol afterwards (E3) Besides the 17120572-ethinyl estradiol(EE) is excreted as conjugated [8]

With regard to emission sources in the first place arethe wastewater treatment plants (WWTPs) [9] and secon-darily cattle waste such as those leachates from dung anduncontrolled dumping [10] Several studies made in theWWTPs have reported that the treatment plants are capableof eliminating around 60 of hormones [11ndash13]

The identification of hormone residues in environmentis of special interest because knowledge of these compoundsis a requirement to take measures in order to regulate andminimize their environmental impact

However measurement of hormone residues is a verydifficult task not only due to the difficulty in measuringvery low concentration but also due to a very complexityof the samples Therefore use of mass spectrometer (MS)as detector coupled with chromatography techniques hasbecome a powerful method for the analysis of these typesof compounds at trace levels [14ndash17] Consequently LC-MSMS is the principally chosen technique One of the mainadvantages of LC-MSMS is its ability to analyze hormoneswithout derivatization (necessary in GC) or the need ofhydrolyze the conjugated form

Due to low level concentration of these compounds inenvironmental water it is necessary to apply an extractionand preconcentration method prior to LC analysis The mostused technique of extraction and preconcentration methodfor liquid samples is the solid phase extraction (SPE) [18ndash20]

The objective of this study is to develop a rapid and simpleprocedure of extraction preconcentration and determina-tion of four steroid oestrogens (estrone (E1) 17120573-estradiol(E2) estriol (E3) and 17120572-ethinylestradiol (EE)) one non-steroidal oestrogen the diethylstilbestrol (DES) one andro-gen the testosterone (TES) and two synthetic progestogensnorgestrel (NOR) and megestrol acetate (MGA) (Table 1)based on solid phase extraction and ultrahigh performanceliquid chromatography-tandem mass spectrometry (SPE-UHPLC-MSMS) The developed method was applied tothe identification and quantification of these compoundsin wastewater samples obtained from the influents andeffluents of two wastewater treatment plants (WWTPs) ofGran Canaria (Spain) They presented different methodsof wastewater treatments WWTP 1 presented a traditionalmethod based on activated sludge while WWTP 2 used amembrane bioreactor technique

2 Materials and Methods

21 Reagents All of the hormonal compounds usedwere pur-chased from Sigma-Aldrich (Madrid Spain) Stock solutionscontaining 1000mgsdotLminus1 of each analyte were prepared by

dissolving the compound inmethanol and the solutionswerestored in glass-stoppered bottles at 4∘C prior to use Workingaqueous standard solutions were prepared daily Ultrapurewater was provided by a Milli-Q system (Millipore BedfordMA USA) HPLC-grade methanol LC-MS methanol andLC-MS water as well as the ammonia and the ammoniumacetate used to adjust the pH of the mobile phases wereobtained from Panreac Quımica (Barcelona Spain)

22 Sample Collection Water samples were collected fromthe effluents of twowastewater treatment plants located in thenorthern area of Gran Canaria in May and August of 2012WWTP 1 used a conventional activated sludge treatmentsystem while WWTP 2 employed a membrane bioreactortreatment system The samples were collected in 2 L amberglass bottles that were rinsed beforehand with methanol andultrapurewater Samples were purified through filtrationwithfibreglass filters and then with 065 120583m membrane filters(Millipore Ireland) The samples were stored in the dark at4∘C and extracted within 48 hours

23 Instrumentation For the SPE optimization the instru-ment used was an ultrahigh performance liquid chromatog-raphy with fluorescence detector (UHPLC-FD) system con-sisting of an ACQUITYQuaternary Solvent Manager (QSM)used to load samples and wash and recondition the analyticalcolumn an autosampler a column manager and a fluores-cence detector with excitation and emission wavelengths of280 and 310 nm respectively all fromWaters (Madrid Spain)

The analysis of wastewater samples was performed ina UHPLC-MSMS system from Waters (Madrid Spain)similar to the described above with a 2777 autosamplerequipped with a 25120583L syringe and a tray to hold 2mLvials and an ACQUITY tandem triple quadrupole (TQD)mass spectrometer with an electrospray ionization (ESI)interface All Waters components (Madrid Spain) werecontrolled using the MassLynx Mass Spectrometry SoftwareElectrospray ionisation parameters were fixed as followsthe capillary voltage was 3 kV in positive mode and minus2 kVin negative mode the source temperature was 150∘C thedesolvation temperature was 500∘C and the desolvation gasflow rate was 1000 Lhr Nitrogen was used as the desolvationgas and argon was employed as the collision gas

The detailed MSMS detection parameters for each hor-monal compound are presented in Table 2 and were opti-mised by the direct injection of a 1mgsdotLminus1 standard solutionof each analyte into the detector at a flow rate of 10 120583Lsdotminminus1

24 Chromatographic Conditions For the SPE optimizationthe analytical column was a 50mm times 21mm ACQUITYUHPLCBEHWaters C

18columnwith a particle size of 17120583m

(Waters Chromatography Barcelona Spain) operating at atemperature of 30∘C Analytes separation was carried outemploying the following gradient starting at 55 45 (vv)water methanol for 1 minute During 3 minutes it changedto 50 50 (vv) and stayed for 25 minutes more Finally cameback to initial conditions in 1 minute and stayed for 15

Journal of Analytical Methods in Chemistry 3

Table 1 List of hormonal compounds pKa values chemical structure and retention times

Compound pKa [21] Structure 119905119877

(min)

E3 Estriol 103

HO

OH

OH

H H

H096

E2 17120573-estradiol 103

HO

OH

H H

H218

EE 17120572-ethinylestradiol 103

HO

HO

H H

H223

E1 Estrone 103

HO

O

H

H H220

DES Diethylstilbestrol 102

HO

OH

235

TES Testosterone 151

OH

OH H

H240

MGA Megestrol acetate

O

O

O

OH

H

H306

NOR Levonorgestrel 131

OH

O

H

H

H

H263

minutes Therefore the analysis took 9 minutes at a flow of05mLsdotminminus1

For the analysis of real samples aUHPLC-MSMS systemwas used The analytical column was the same and themobile phase was water and methanol adjusted with a bufferconsisting in 01 vv ammonia and 15mM of ammoniumacetate The analysis was performed in gradient mode at aflow rate of 03mLsdotminminus1The gradient started at 50 50 (vv)mixture of water methanol which changed to 25 75 (vv) in3 minutes and returned to 50 50 in 1 minute more Finallythe gradient stayed calibrating for another 15 minutes moreThe sample volume injected was 5120583L

3 Results and Discussion

31 Optimization of Solid-Phase Extraction (SPE) There area number of parameters that affect SPE procedure such as

type of sorbent pH ionic strength sample and desorptionvolumes and wash step To optimize these parameters itused Milli-Q water spiked with a solution of fluorescenceoestrogens (estriol 17120573-estradiol and 17120572-ethinylestradiol)to obtain a final concentration of 250120583gsdotLminus1

The first parameter to optimize is the choice of sorbentsince it controls the selectivity affinity and capacity overanalytes In this study the SPE cartridges used were OASISHLB SepPak C

18(both from Waters Madrid Spain) and

BondElut ENV (fromAgilent Madrid Spain) Keeping otherparameters fixed (ionic strength of 0 sample volume of100mL) the cartridges were studied at three different pHs(5 8 and 11) From the results obtained it can be observedthat the better signals are found for SepPak C

18cartridge

(Figure 1)After choosing the optimum cartridge we used an initial

experimental design of 23 to study the influence of pH ionic

4 Journal of Analytical Methods in Chemistry

Table 2 Mass spectrometer parameters for the determination of target analytes

Compound Precursor ion(mz)

Capillary voltage(Ion mode)

Quantification ionmz(collision potential V)

Quantification ionmz(collision potential V)

E3 2872 minus65V (ESI minus) 1710 (37) 1452 (39)E2 2712 minus65V (ESI minus) 1451 (40) 1831 (31)EE 2952 minus60V (ESI minus) 1450 (37) 1589 (33)E1 2692 minus65V (ESI minus) 1450 (36) 1430 (48)DES 2671 minus50V (ESI minus) 2371 (29) 2511 (25)TES 2892 38V (ESI +) 1870 (18) 1040 (21)MGA 3855 30V (ESI +) 2673 (15) 2242 (30)NOR 3132 38V (ESI +) 1090 (26) 2451 (18)

0

500

1000

1500

2000

2500

E3 E2 EE

Peak

area

Cartridge optimizationOASIS HLB pH = 5

OASIS HLB pH = 8

OASIS HLB pH = 11SepPak C18 pH = 5

SepPak C18 pH = 8

SepPak C18 pH = 11BondElut ENV pH = 5

BondElut ENV pH = 8

BondElut ENV pH =11

Figure 1 Optimization of SPE cartridges

strength and sample volume over extraction process Theexperimental design was obtained using Statgraphics Plussoftware 51 and the statistics study was done with IBM SPSSStatistics 19 We assessed two levels and three parameters pH(3 and 8) ionic strength (0 and 30 of NaCl) and samplevolume (50 and 250mL) to obtain the influence of eachparameter and the variable correlation to each other In thisstudy it is observed that the ionic strength and sample volumehad the major influence on the recoveries of the analytesFor that a 32 factorial design to optimize these two variablesat three levels per parameter (0 15 and 30 of NaCl forionic strength and 50 100 y 250mL for sample volume) wasused Figure 2 shows the response surface obtained for theestriol and 17120572-ethinylestradiol The results obtained showedthat an increment of the ionic strength did not producean increase in the response area of the compound and theoptimum volume was 250mL Because of that a solutionwithout salt addition and 250mL of sample volume waschosen Finally the desorption volume (1mLofmethanol and2mL of methanol in one and two steps) and wash-step (5mL

ofMilli-Q water and 5mL ofMilli-Q water with 5 and 10 ofmethanol vv) were assayed to complete the optimization ofthe SPE process The optimum values were 2mL of methanolin one step and 5mL of Milli-Q water without methanolrespectively

In accordance with the obtained results the optimumconditions for SPE procedure were SepPak C

18cartridge

250mL of sample at pH = 8 and 0 of NaCl desorptionwith 2mL of methanol in one step and wash step with5mL of Milli-Q water In these conditions we achieved apreconcentration factor of 125 In Figure 3 a chromatogramwith the optimum conditions is shown where the peaksof all compounds in their corresponding transitions can beobserved

32 Analytical Parameters Because of the SPE optimizationthat was done only with fluorescent compounds (estriol 17120573-estradiol and 17120572-ethinylestradiol) it was necessary to studythe recoveries of all the hormonal compounds using theoptimized SPE-UHPLC-MSMSmethod All the compoundsunder study showed good recoveries over 73 except thediethylstilbestrol with a recovery of 507

A calibration curve was used for the quantification ofthe analytes by diluting the stock solution of each analyteinto the samples to concentrations ranging between 1 and100 120583gsdotLminus1 Analysis was conducted by UHPLC-MSMS andlinear calibration plots for each analyte (1199032 gt 099) wereobtained based on their chromatographic peak areas

The limit of detection (LOD) and the limit of quantifi-cation (LOQ) for each compound were calculated from thesignal-to-noise ratio of each individual peak The LOD wasdefined as the lowest concentration that gave a signal-to-noiseratio that was greater than 3 The LOQ was defined as thelowest concentration that gave a signal to noise ratio that wasgreater than 10The LODs ranged from015 to 935 ngsdotLminus1 andthe LOQs ranged from 049 to 3118 ngsdotLminus1

The performance and reliability of the process werestudied by determining the repeatability of the quantificationresults for all target analytes under the described conditionsusing six samples (119899 = 6) The relative standard deviations(RSDs) were lower than 84 in all cases indicating a

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 16: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 210653 8 pageshttpdxdoiorg1011552013210653

Research ArticleSimultaneous Determination of Hormonal Residuesin Treated Waters Using Ultrahigh Performance LiquidChromatography-Tandem Mass Spectrometry

Rayco Guedes-Alonso Zoraida Sosa-Ferrera and Joseacute Juan Santana-Rodriacuteguez

Departamento de Quımica Universidad de Las Palmas de Gran Canaria 35017 Las Palmas de Gran Canaria Spain

Correspondence should be addressed to Jose Juan Santana-Rodrıguez jsantanadquiulpgces

Received 28 December 2012 Accepted 7 February 2013

Academic Editor Fei Qi

Copyright copy 2013 Rayco Guedes-Alonso et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

In the last years hormone consumption has increased exponentially Because of that hormone compounds are considered emergingpollutants since several studies have determinted their presence in water influents and effluents of wastewater treatment plants(WWTPs) In this study a quantitative method for the simultaneous determination of oestrogens (estrone 17120573-estradiol estriol17120572-ethinylestradiol and diethylstilbestrol) androgens (testosterone) and progestogens (norgestrel andmegestrol acetate) has beendeveloped to determine these compounds in wastewater samples Due to the very low concentrations of target compounds in theenvironment a solid phase extraction procedure has been optimized and developed to extract and preconcentrate the analytesDetermination and quantification were performed by ultrahigh performance liquid chromatography-tandem mass spectrometry(UHPLC-MSMS) The method developed presents satisfactory limits of detection (between 015 and 935 ngsdotLminus1) good recoveries(between 73 and 90 for the most of compounds) and low relative standard deviations (under 84) Samples from influents andeffluents of two wastewater treatment plants of Gran Canaria (Spain) were analyzed using the proposed method finding severalhormones with concentrations ranged from 5 to 300 ngsdotLminus1

1 Introduction

In general it is supposed that more than 100000 differentchemical compounds can be introduced in the Environmentmany of them in very small quantity However a lot of thesecompounds are not included as pollutants in the legislationAlthough these compounds named emerging pollutants arenot regulated as pollutants they probably will be in the futurebecause of their potential negative effect in the ecosystem For20 years many articles have reported the presence of theseldquonew compoundsrdquo in wastewater [1 2]

The emerging pollutant origin is mainly anthropogenicconsidering that the majority of these compounds are bio-logically active substances that are synthesized to use themin agriculture industry and medicine The main source ofthese emerging pollutants is the residual urbanwaters and thewastewater treatment plants effluents because many of these

WWTPs are not designed or optimized to treat this kind ofcompounds [3]

Hormones are one of the most potent endocrine disrupt-ing compounds as well as are considered also as emergingpollutants Hormones can be differentiated in oestrogensandrogens and progestogens Some of them have limits intheir use but not a specific legislation [4]

The main characteristic of these pollutants is that it isnot necessary to remain in the environment to cause negativeeffects in view of the fact that their constant introduction init offsets their removal or degradation [5]

The steroid hormones help controlling the metabolisminflammations immunological functions water and salt bal-ance sexual development and the capacity of withstandingillnesses [6] The term steroid can be used for naturalhormones produced by the body as well as for artificiallyproduced medicines that increase the natural steroid effect

2 Journal of Analytical Methods in Chemistry

In the last 50 years the natural and synthetic hormoneworldwide consumption has grown as much as in humanmedicine as in cattle farming and they become the mostprescribed medicines [7]

A significant quantity of consumed oestrogens leaves theorganism through excretions For example 17120573-estradiol (E2)is oxidized rapidly becoming an estrone (E1) that can turninto estriol afterwards (E3) Besides the 17120572-ethinyl estradiol(EE) is excreted as conjugated [8]

With regard to emission sources in the first place arethe wastewater treatment plants (WWTPs) [9] and secon-darily cattle waste such as those leachates from dung anduncontrolled dumping [10] Several studies made in theWWTPs have reported that the treatment plants are capableof eliminating around 60 of hormones [11ndash13]

The identification of hormone residues in environmentis of special interest because knowledge of these compoundsis a requirement to take measures in order to regulate andminimize their environmental impact

However measurement of hormone residues is a verydifficult task not only due to the difficulty in measuringvery low concentration but also due to a very complexityof the samples Therefore use of mass spectrometer (MS)as detector coupled with chromatography techniques hasbecome a powerful method for the analysis of these typesof compounds at trace levels [14ndash17] Consequently LC-MSMS is the principally chosen technique One of the mainadvantages of LC-MSMS is its ability to analyze hormoneswithout derivatization (necessary in GC) or the need ofhydrolyze the conjugated form

Due to low level concentration of these compounds inenvironmental water it is necessary to apply an extractionand preconcentration method prior to LC analysis The mostused technique of extraction and preconcentration methodfor liquid samples is the solid phase extraction (SPE) [18ndash20]

The objective of this study is to develop a rapid and simpleprocedure of extraction preconcentration and determina-tion of four steroid oestrogens (estrone (E1) 17120573-estradiol(E2) estriol (E3) and 17120572-ethinylestradiol (EE)) one non-steroidal oestrogen the diethylstilbestrol (DES) one andro-gen the testosterone (TES) and two synthetic progestogensnorgestrel (NOR) and megestrol acetate (MGA) (Table 1)based on solid phase extraction and ultrahigh performanceliquid chromatography-tandem mass spectrometry (SPE-UHPLC-MSMS) The developed method was applied tothe identification and quantification of these compoundsin wastewater samples obtained from the influents andeffluents of two wastewater treatment plants (WWTPs) ofGran Canaria (Spain) They presented different methodsof wastewater treatments WWTP 1 presented a traditionalmethod based on activated sludge while WWTP 2 used amembrane bioreactor technique

2 Materials and Methods

21 Reagents All of the hormonal compounds usedwere pur-chased from Sigma-Aldrich (Madrid Spain) Stock solutionscontaining 1000mgsdotLminus1 of each analyte were prepared by

dissolving the compound inmethanol and the solutionswerestored in glass-stoppered bottles at 4∘C prior to use Workingaqueous standard solutions were prepared daily Ultrapurewater was provided by a Milli-Q system (Millipore BedfordMA USA) HPLC-grade methanol LC-MS methanol andLC-MS water as well as the ammonia and the ammoniumacetate used to adjust the pH of the mobile phases wereobtained from Panreac Quımica (Barcelona Spain)

22 Sample Collection Water samples were collected fromthe effluents of twowastewater treatment plants located in thenorthern area of Gran Canaria in May and August of 2012WWTP 1 used a conventional activated sludge treatmentsystem while WWTP 2 employed a membrane bioreactortreatment system The samples were collected in 2 L amberglass bottles that were rinsed beforehand with methanol andultrapurewater Samples were purified through filtrationwithfibreglass filters and then with 065 120583m membrane filters(Millipore Ireland) The samples were stored in the dark at4∘C and extracted within 48 hours

23 Instrumentation For the SPE optimization the instru-ment used was an ultrahigh performance liquid chromatog-raphy with fluorescence detector (UHPLC-FD) system con-sisting of an ACQUITYQuaternary Solvent Manager (QSM)used to load samples and wash and recondition the analyticalcolumn an autosampler a column manager and a fluores-cence detector with excitation and emission wavelengths of280 and 310 nm respectively all fromWaters (Madrid Spain)

The analysis of wastewater samples was performed ina UHPLC-MSMS system from Waters (Madrid Spain)similar to the described above with a 2777 autosamplerequipped with a 25120583L syringe and a tray to hold 2mLvials and an ACQUITY tandem triple quadrupole (TQD)mass spectrometer with an electrospray ionization (ESI)interface All Waters components (Madrid Spain) werecontrolled using the MassLynx Mass Spectrometry SoftwareElectrospray ionisation parameters were fixed as followsthe capillary voltage was 3 kV in positive mode and minus2 kVin negative mode the source temperature was 150∘C thedesolvation temperature was 500∘C and the desolvation gasflow rate was 1000 Lhr Nitrogen was used as the desolvationgas and argon was employed as the collision gas

The detailed MSMS detection parameters for each hor-monal compound are presented in Table 2 and were opti-mised by the direct injection of a 1mgsdotLminus1 standard solutionof each analyte into the detector at a flow rate of 10 120583Lsdotminminus1

24 Chromatographic Conditions For the SPE optimizationthe analytical column was a 50mm times 21mm ACQUITYUHPLCBEHWaters C

18columnwith a particle size of 17120583m

(Waters Chromatography Barcelona Spain) operating at atemperature of 30∘C Analytes separation was carried outemploying the following gradient starting at 55 45 (vv)water methanol for 1 minute During 3 minutes it changedto 50 50 (vv) and stayed for 25 minutes more Finally cameback to initial conditions in 1 minute and stayed for 15

Journal of Analytical Methods in Chemistry 3

Table 1 List of hormonal compounds pKa values chemical structure and retention times

Compound pKa [21] Structure 119905119877

(min)

E3 Estriol 103

HO

OH

OH

H H

H096

E2 17120573-estradiol 103

HO

OH

H H

H218

EE 17120572-ethinylestradiol 103

HO

HO

H H

H223

E1 Estrone 103

HO

O

H

H H220

DES Diethylstilbestrol 102

HO

OH

235

TES Testosterone 151

OH

OH H

H240

MGA Megestrol acetate

O

O

O

OH

H

H306

NOR Levonorgestrel 131

OH

O

H

H

H

H263

minutes Therefore the analysis took 9 minutes at a flow of05mLsdotminminus1

For the analysis of real samples aUHPLC-MSMS systemwas used The analytical column was the same and themobile phase was water and methanol adjusted with a bufferconsisting in 01 vv ammonia and 15mM of ammoniumacetate The analysis was performed in gradient mode at aflow rate of 03mLsdotminminus1The gradient started at 50 50 (vv)mixture of water methanol which changed to 25 75 (vv) in3 minutes and returned to 50 50 in 1 minute more Finallythe gradient stayed calibrating for another 15 minutes moreThe sample volume injected was 5120583L

3 Results and Discussion

31 Optimization of Solid-Phase Extraction (SPE) There area number of parameters that affect SPE procedure such as

type of sorbent pH ionic strength sample and desorptionvolumes and wash step To optimize these parameters itused Milli-Q water spiked with a solution of fluorescenceoestrogens (estriol 17120573-estradiol and 17120572-ethinylestradiol)to obtain a final concentration of 250120583gsdotLminus1

The first parameter to optimize is the choice of sorbentsince it controls the selectivity affinity and capacity overanalytes In this study the SPE cartridges used were OASISHLB SepPak C

18(both from Waters Madrid Spain) and

BondElut ENV (fromAgilent Madrid Spain) Keeping otherparameters fixed (ionic strength of 0 sample volume of100mL) the cartridges were studied at three different pHs(5 8 and 11) From the results obtained it can be observedthat the better signals are found for SepPak C

18cartridge

(Figure 1)After choosing the optimum cartridge we used an initial

experimental design of 23 to study the influence of pH ionic

4 Journal of Analytical Methods in Chemistry

Table 2 Mass spectrometer parameters for the determination of target analytes

Compound Precursor ion(mz)

Capillary voltage(Ion mode)

Quantification ionmz(collision potential V)

Quantification ionmz(collision potential V)

E3 2872 minus65V (ESI minus) 1710 (37) 1452 (39)E2 2712 minus65V (ESI minus) 1451 (40) 1831 (31)EE 2952 minus60V (ESI minus) 1450 (37) 1589 (33)E1 2692 minus65V (ESI minus) 1450 (36) 1430 (48)DES 2671 minus50V (ESI minus) 2371 (29) 2511 (25)TES 2892 38V (ESI +) 1870 (18) 1040 (21)MGA 3855 30V (ESI +) 2673 (15) 2242 (30)NOR 3132 38V (ESI +) 1090 (26) 2451 (18)

0

500

1000

1500

2000

2500

E3 E2 EE

Peak

area

Cartridge optimizationOASIS HLB pH = 5

OASIS HLB pH = 8

OASIS HLB pH = 11SepPak C18 pH = 5

SepPak C18 pH = 8

SepPak C18 pH = 11BondElut ENV pH = 5

BondElut ENV pH = 8

BondElut ENV pH =11

Figure 1 Optimization of SPE cartridges

strength and sample volume over extraction process Theexperimental design was obtained using Statgraphics Plussoftware 51 and the statistics study was done with IBM SPSSStatistics 19 We assessed two levels and three parameters pH(3 and 8) ionic strength (0 and 30 of NaCl) and samplevolume (50 and 250mL) to obtain the influence of eachparameter and the variable correlation to each other In thisstudy it is observed that the ionic strength and sample volumehad the major influence on the recoveries of the analytesFor that a 32 factorial design to optimize these two variablesat three levels per parameter (0 15 and 30 of NaCl forionic strength and 50 100 y 250mL for sample volume) wasused Figure 2 shows the response surface obtained for theestriol and 17120572-ethinylestradiol The results obtained showedthat an increment of the ionic strength did not producean increase in the response area of the compound and theoptimum volume was 250mL Because of that a solutionwithout salt addition and 250mL of sample volume waschosen Finally the desorption volume (1mLofmethanol and2mL of methanol in one and two steps) and wash-step (5mL

ofMilli-Q water and 5mL ofMilli-Q water with 5 and 10 ofmethanol vv) were assayed to complete the optimization ofthe SPE process The optimum values were 2mL of methanolin one step and 5mL of Milli-Q water without methanolrespectively

In accordance with the obtained results the optimumconditions for SPE procedure were SepPak C

18cartridge

250mL of sample at pH = 8 and 0 of NaCl desorptionwith 2mL of methanol in one step and wash step with5mL of Milli-Q water In these conditions we achieved apreconcentration factor of 125 In Figure 3 a chromatogramwith the optimum conditions is shown where the peaksof all compounds in their corresponding transitions can beobserved

32 Analytical Parameters Because of the SPE optimizationthat was done only with fluorescent compounds (estriol 17120573-estradiol and 17120572-ethinylestradiol) it was necessary to studythe recoveries of all the hormonal compounds using theoptimized SPE-UHPLC-MSMSmethod All the compoundsunder study showed good recoveries over 73 except thediethylstilbestrol with a recovery of 507

A calibration curve was used for the quantification ofthe analytes by diluting the stock solution of each analyteinto the samples to concentrations ranging between 1 and100 120583gsdotLminus1 Analysis was conducted by UHPLC-MSMS andlinear calibration plots for each analyte (1199032 gt 099) wereobtained based on their chromatographic peak areas

The limit of detection (LOD) and the limit of quantifi-cation (LOQ) for each compound were calculated from thesignal-to-noise ratio of each individual peak The LOD wasdefined as the lowest concentration that gave a signal-to-noiseratio that was greater than 3 The LOQ was defined as thelowest concentration that gave a signal to noise ratio that wasgreater than 10The LODs ranged from015 to 935 ngsdotLminus1 andthe LOQs ranged from 049 to 3118 ngsdotLminus1

The performance and reliability of the process werestudied by determining the repeatability of the quantificationresults for all target analytes under the described conditionsusing six samples (119899 = 6) The relative standard deviations(RSDs) were lower than 84 in all cases indicating a

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 17: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

2 Journal of Analytical Methods in Chemistry

In the last 50 years the natural and synthetic hormoneworldwide consumption has grown as much as in humanmedicine as in cattle farming and they become the mostprescribed medicines [7]

A significant quantity of consumed oestrogens leaves theorganism through excretions For example 17120573-estradiol (E2)is oxidized rapidly becoming an estrone (E1) that can turninto estriol afterwards (E3) Besides the 17120572-ethinyl estradiol(EE) is excreted as conjugated [8]

With regard to emission sources in the first place arethe wastewater treatment plants (WWTPs) [9] and secon-darily cattle waste such as those leachates from dung anduncontrolled dumping [10] Several studies made in theWWTPs have reported that the treatment plants are capableof eliminating around 60 of hormones [11ndash13]

The identification of hormone residues in environmentis of special interest because knowledge of these compoundsis a requirement to take measures in order to regulate andminimize their environmental impact

However measurement of hormone residues is a verydifficult task not only due to the difficulty in measuringvery low concentration but also due to a very complexityof the samples Therefore use of mass spectrometer (MS)as detector coupled with chromatography techniques hasbecome a powerful method for the analysis of these typesof compounds at trace levels [14ndash17] Consequently LC-MSMS is the principally chosen technique One of the mainadvantages of LC-MSMS is its ability to analyze hormoneswithout derivatization (necessary in GC) or the need ofhydrolyze the conjugated form

Due to low level concentration of these compounds inenvironmental water it is necessary to apply an extractionand preconcentration method prior to LC analysis The mostused technique of extraction and preconcentration methodfor liquid samples is the solid phase extraction (SPE) [18ndash20]

The objective of this study is to develop a rapid and simpleprocedure of extraction preconcentration and determina-tion of four steroid oestrogens (estrone (E1) 17120573-estradiol(E2) estriol (E3) and 17120572-ethinylestradiol (EE)) one non-steroidal oestrogen the diethylstilbestrol (DES) one andro-gen the testosterone (TES) and two synthetic progestogensnorgestrel (NOR) and megestrol acetate (MGA) (Table 1)based on solid phase extraction and ultrahigh performanceliquid chromatography-tandem mass spectrometry (SPE-UHPLC-MSMS) The developed method was applied tothe identification and quantification of these compoundsin wastewater samples obtained from the influents andeffluents of two wastewater treatment plants (WWTPs) ofGran Canaria (Spain) They presented different methodsof wastewater treatments WWTP 1 presented a traditionalmethod based on activated sludge while WWTP 2 used amembrane bioreactor technique

2 Materials and Methods

21 Reagents All of the hormonal compounds usedwere pur-chased from Sigma-Aldrich (Madrid Spain) Stock solutionscontaining 1000mgsdotLminus1 of each analyte were prepared by

dissolving the compound inmethanol and the solutionswerestored in glass-stoppered bottles at 4∘C prior to use Workingaqueous standard solutions were prepared daily Ultrapurewater was provided by a Milli-Q system (Millipore BedfordMA USA) HPLC-grade methanol LC-MS methanol andLC-MS water as well as the ammonia and the ammoniumacetate used to adjust the pH of the mobile phases wereobtained from Panreac Quımica (Barcelona Spain)

22 Sample Collection Water samples were collected fromthe effluents of twowastewater treatment plants located in thenorthern area of Gran Canaria in May and August of 2012WWTP 1 used a conventional activated sludge treatmentsystem while WWTP 2 employed a membrane bioreactortreatment system The samples were collected in 2 L amberglass bottles that were rinsed beforehand with methanol andultrapurewater Samples were purified through filtrationwithfibreglass filters and then with 065 120583m membrane filters(Millipore Ireland) The samples were stored in the dark at4∘C and extracted within 48 hours

23 Instrumentation For the SPE optimization the instru-ment used was an ultrahigh performance liquid chromatog-raphy with fluorescence detector (UHPLC-FD) system con-sisting of an ACQUITYQuaternary Solvent Manager (QSM)used to load samples and wash and recondition the analyticalcolumn an autosampler a column manager and a fluores-cence detector with excitation and emission wavelengths of280 and 310 nm respectively all fromWaters (Madrid Spain)

The analysis of wastewater samples was performed ina UHPLC-MSMS system from Waters (Madrid Spain)similar to the described above with a 2777 autosamplerequipped with a 25120583L syringe and a tray to hold 2mLvials and an ACQUITY tandem triple quadrupole (TQD)mass spectrometer with an electrospray ionization (ESI)interface All Waters components (Madrid Spain) werecontrolled using the MassLynx Mass Spectrometry SoftwareElectrospray ionisation parameters were fixed as followsthe capillary voltage was 3 kV in positive mode and minus2 kVin negative mode the source temperature was 150∘C thedesolvation temperature was 500∘C and the desolvation gasflow rate was 1000 Lhr Nitrogen was used as the desolvationgas and argon was employed as the collision gas

The detailed MSMS detection parameters for each hor-monal compound are presented in Table 2 and were opti-mised by the direct injection of a 1mgsdotLminus1 standard solutionof each analyte into the detector at a flow rate of 10 120583Lsdotminminus1

24 Chromatographic Conditions For the SPE optimizationthe analytical column was a 50mm times 21mm ACQUITYUHPLCBEHWaters C

18columnwith a particle size of 17120583m

(Waters Chromatography Barcelona Spain) operating at atemperature of 30∘C Analytes separation was carried outemploying the following gradient starting at 55 45 (vv)water methanol for 1 minute During 3 minutes it changedto 50 50 (vv) and stayed for 25 minutes more Finally cameback to initial conditions in 1 minute and stayed for 15

Journal of Analytical Methods in Chemistry 3

Table 1 List of hormonal compounds pKa values chemical structure and retention times

Compound pKa [21] Structure 119905119877

(min)

E3 Estriol 103

HO

OH

OH

H H

H096

E2 17120573-estradiol 103

HO

OH

H H

H218

EE 17120572-ethinylestradiol 103

HO

HO

H H

H223

E1 Estrone 103

HO

O

H

H H220

DES Diethylstilbestrol 102

HO

OH

235

TES Testosterone 151

OH

OH H

H240

MGA Megestrol acetate

O

O

O

OH

H

H306

NOR Levonorgestrel 131

OH

O

H

H

H

H263

minutes Therefore the analysis took 9 minutes at a flow of05mLsdotminminus1

For the analysis of real samples aUHPLC-MSMS systemwas used The analytical column was the same and themobile phase was water and methanol adjusted with a bufferconsisting in 01 vv ammonia and 15mM of ammoniumacetate The analysis was performed in gradient mode at aflow rate of 03mLsdotminminus1The gradient started at 50 50 (vv)mixture of water methanol which changed to 25 75 (vv) in3 minutes and returned to 50 50 in 1 minute more Finallythe gradient stayed calibrating for another 15 minutes moreThe sample volume injected was 5120583L

3 Results and Discussion

31 Optimization of Solid-Phase Extraction (SPE) There area number of parameters that affect SPE procedure such as

type of sorbent pH ionic strength sample and desorptionvolumes and wash step To optimize these parameters itused Milli-Q water spiked with a solution of fluorescenceoestrogens (estriol 17120573-estradiol and 17120572-ethinylestradiol)to obtain a final concentration of 250120583gsdotLminus1

The first parameter to optimize is the choice of sorbentsince it controls the selectivity affinity and capacity overanalytes In this study the SPE cartridges used were OASISHLB SepPak C

18(both from Waters Madrid Spain) and

BondElut ENV (fromAgilent Madrid Spain) Keeping otherparameters fixed (ionic strength of 0 sample volume of100mL) the cartridges were studied at three different pHs(5 8 and 11) From the results obtained it can be observedthat the better signals are found for SepPak C

18cartridge

(Figure 1)After choosing the optimum cartridge we used an initial

experimental design of 23 to study the influence of pH ionic

4 Journal of Analytical Methods in Chemistry

Table 2 Mass spectrometer parameters for the determination of target analytes

Compound Precursor ion(mz)

Capillary voltage(Ion mode)

Quantification ionmz(collision potential V)

Quantification ionmz(collision potential V)

E3 2872 minus65V (ESI minus) 1710 (37) 1452 (39)E2 2712 minus65V (ESI minus) 1451 (40) 1831 (31)EE 2952 minus60V (ESI minus) 1450 (37) 1589 (33)E1 2692 minus65V (ESI minus) 1450 (36) 1430 (48)DES 2671 minus50V (ESI minus) 2371 (29) 2511 (25)TES 2892 38V (ESI +) 1870 (18) 1040 (21)MGA 3855 30V (ESI +) 2673 (15) 2242 (30)NOR 3132 38V (ESI +) 1090 (26) 2451 (18)

0

500

1000

1500

2000

2500

E3 E2 EE

Peak

area

Cartridge optimizationOASIS HLB pH = 5

OASIS HLB pH = 8

OASIS HLB pH = 11SepPak C18 pH = 5

SepPak C18 pH = 8

SepPak C18 pH = 11BondElut ENV pH = 5

BondElut ENV pH = 8

BondElut ENV pH =11

Figure 1 Optimization of SPE cartridges

strength and sample volume over extraction process Theexperimental design was obtained using Statgraphics Plussoftware 51 and the statistics study was done with IBM SPSSStatistics 19 We assessed two levels and three parameters pH(3 and 8) ionic strength (0 and 30 of NaCl) and samplevolume (50 and 250mL) to obtain the influence of eachparameter and the variable correlation to each other In thisstudy it is observed that the ionic strength and sample volumehad the major influence on the recoveries of the analytesFor that a 32 factorial design to optimize these two variablesat three levels per parameter (0 15 and 30 of NaCl forionic strength and 50 100 y 250mL for sample volume) wasused Figure 2 shows the response surface obtained for theestriol and 17120572-ethinylestradiol The results obtained showedthat an increment of the ionic strength did not producean increase in the response area of the compound and theoptimum volume was 250mL Because of that a solutionwithout salt addition and 250mL of sample volume waschosen Finally the desorption volume (1mLofmethanol and2mL of methanol in one and two steps) and wash-step (5mL

ofMilli-Q water and 5mL ofMilli-Q water with 5 and 10 ofmethanol vv) were assayed to complete the optimization ofthe SPE process The optimum values were 2mL of methanolin one step and 5mL of Milli-Q water without methanolrespectively

In accordance with the obtained results the optimumconditions for SPE procedure were SepPak C

18cartridge

250mL of sample at pH = 8 and 0 of NaCl desorptionwith 2mL of methanol in one step and wash step with5mL of Milli-Q water In these conditions we achieved apreconcentration factor of 125 In Figure 3 a chromatogramwith the optimum conditions is shown where the peaksof all compounds in their corresponding transitions can beobserved

32 Analytical Parameters Because of the SPE optimizationthat was done only with fluorescent compounds (estriol 17120573-estradiol and 17120572-ethinylestradiol) it was necessary to studythe recoveries of all the hormonal compounds using theoptimized SPE-UHPLC-MSMSmethod All the compoundsunder study showed good recoveries over 73 except thediethylstilbestrol with a recovery of 507

A calibration curve was used for the quantification ofthe analytes by diluting the stock solution of each analyteinto the samples to concentrations ranging between 1 and100 120583gsdotLminus1 Analysis was conducted by UHPLC-MSMS andlinear calibration plots for each analyte (1199032 gt 099) wereobtained based on their chromatographic peak areas

The limit of detection (LOD) and the limit of quantifi-cation (LOQ) for each compound were calculated from thesignal-to-noise ratio of each individual peak The LOD wasdefined as the lowest concentration that gave a signal-to-noiseratio that was greater than 3 The LOQ was defined as thelowest concentration that gave a signal to noise ratio that wasgreater than 10The LODs ranged from015 to 935 ngsdotLminus1 andthe LOQs ranged from 049 to 3118 ngsdotLminus1

The performance and reliability of the process werestudied by determining the repeatability of the quantificationresults for all target analytes under the described conditionsusing six samples (119899 = 6) The relative standard deviations(RSDs) were lower than 84 in all cases indicating a

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 18: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Journal of Analytical Methods in Chemistry 3

Table 1 List of hormonal compounds pKa values chemical structure and retention times

Compound pKa [21] Structure 119905119877

(min)

E3 Estriol 103

HO

OH

OH

H H

H096

E2 17120573-estradiol 103

HO

OH

H H

H218

EE 17120572-ethinylestradiol 103

HO

HO

H H

H223

E1 Estrone 103

HO

O

H

H H220

DES Diethylstilbestrol 102

HO

OH

235

TES Testosterone 151

OH

OH H

H240

MGA Megestrol acetate

O

O

O

OH

H

H306

NOR Levonorgestrel 131

OH

O

H

H

H

H263

minutes Therefore the analysis took 9 minutes at a flow of05mLsdotminminus1

For the analysis of real samples aUHPLC-MSMS systemwas used The analytical column was the same and themobile phase was water and methanol adjusted with a bufferconsisting in 01 vv ammonia and 15mM of ammoniumacetate The analysis was performed in gradient mode at aflow rate of 03mLsdotminminus1The gradient started at 50 50 (vv)mixture of water methanol which changed to 25 75 (vv) in3 minutes and returned to 50 50 in 1 minute more Finallythe gradient stayed calibrating for another 15 minutes moreThe sample volume injected was 5120583L

3 Results and Discussion

31 Optimization of Solid-Phase Extraction (SPE) There area number of parameters that affect SPE procedure such as

type of sorbent pH ionic strength sample and desorptionvolumes and wash step To optimize these parameters itused Milli-Q water spiked with a solution of fluorescenceoestrogens (estriol 17120573-estradiol and 17120572-ethinylestradiol)to obtain a final concentration of 250120583gsdotLminus1

The first parameter to optimize is the choice of sorbentsince it controls the selectivity affinity and capacity overanalytes In this study the SPE cartridges used were OASISHLB SepPak C

18(both from Waters Madrid Spain) and

BondElut ENV (fromAgilent Madrid Spain) Keeping otherparameters fixed (ionic strength of 0 sample volume of100mL) the cartridges were studied at three different pHs(5 8 and 11) From the results obtained it can be observedthat the better signals are found for SepPak C

18cartridge

(Figure 1)After choosing the optimum cartridge we used an initial

experimental design of 23 to study the influence of pH ionic

4 Journal of Analytical Methods in Chemistry

Table 2 Mass spectrometer parameters for the determination of target analytes

Compound Precursor ion(mz)

Capillary voltage(Ion mode)

Quantification ionmz(collision potential V)

Quantification ionmz(collision potential V)

E3 2872 minus65V (ESI minus) 1710 (37) 1452 (39)E2 2712 minus65V (ESI minus) 1451 (40) 1831 (31)EE 2952 minus60V (ESI minus) 1450 (37) 1589 (33)E1 2692 minus65V (ESI minus) 1450 (36) 1430 (48)DES 2671 minus50V (ESI minus) 2371 (29) 2511 (25)TES 2892 38V (ESI +) 1870 (18) 1040 (21)MGA 3855 30V (ESI +) 2673 (15) 2242 (30)NOR 3132 38V (ESI +) 1090 (26) 2451 (18)

0

500

1000

1500

2000

2500

E3 E2 EE

Peak

area

Cartridge optimizationOASIS HLB pH = 5

OASIS HLB pH = 8

OASIS HLB pH = 11SepPak C18 pH = 5

SepPak C18 pH = 8

SepPak C18 pH = 11BondElut ENV pH = 5

BondElut ENV pH = 8

BondElut ENV pH =11

Figure 1 Optimization of SPE cartridges

strength and sample volume over extraction process Theexperimental design was obtained using Statgraphics Plussoftware 51 and the statistics study was done with IBM SPSSStatistics 19 We assessed two levels and three parameters pH(3 and 8) ionic strength (0 and 30 of NaCl) and samplevolume (50 and 250mL) to obtain the influence of eachparameter and the variable correlation to each other In thisstudy it is observed that the ionic strength and sample volumehad the major influence on the recoveries of the analytesFor that a 32 factorial design to optimize these two variablesat three levels per parameter (0 15 and 30 of NaCl forionic strength and 50 100 y 250mL for sample volume) wasused Figure 2 shows the response surface obtained for theestriol and 17120572-ethinylestradiol The results obtained showedthat an increment of the ionic strength did not producean increase in the response area of the compound and theoptimum volume was 250mL Because of that a solutionwithout salt addition and 250mL of sample volume waschosen Finally the desorption volume (1mLofmethanol and2mL of methanol in one and two steps) and wash-step (5mL

ofMilli-Q water and 5mL ofMilli-Q water with 5 and 10 ofmethanol vv) were assayed to complete the optimization ofthe SPE process The optimum values were 2mL of methanolin one step and 5mL of Milli-Q water without methanolrespectively

In accordance with the obtained results the optimumconditions for SPE procedure were SepPak C

18cartridge

250mL of sample at pH = 8 and 0 of NaCl desorptionwith 2mL of methanol in one step and wash step with5mL of Milli-Q water In these conditions we achieved apreconcentration factor of 125 In Figure 3 a chromatogramwith the optimum conditions is shown where the peaksof all compounds in their corresponding transitions can beobserved

32 Analytical Parameters Because of the SPE optimizationthat was done only with fluorescent compounds (estriol 17120573-estradiol and 17120572-ethinylestradiol) it was necessary to studythe recoveries of all the hormonal compounds using theoptimized SPE-UHPLC-MSMSmethod All the compoundsunder study showed good recoveries over 73 except thediethylstilbestrol with a recovery of 507

A calibration curve was used for the quantification ofthe analytes by diluting the stock solution of each analyteinto the samples to concentrations ranging between 1 and100 120583gsdotLminus1 Analysis was conducted by UHPLC-MSMS andlinear calibration plots for each analyte (1199032 gt 099) wereobtained based on their chromatographic peak areas

The limit of detection (LOD) and the limit of quantifi-cation (LOQ) for each compound were calculated from thesignal-to-noise ratio of each individual peak The LOD wasdefined as the lowest concentration that gave a signal-to-noiseratio that was greater than 3 The LOQ was defined as thelowest concentration that gave a signal to noise ratio that wasgreater than 10The LODs ranged from015 to 935 ngsdotLminus1 andthe LOQs ranged from 049 to 3118 ngsdotLminus1

The performance and reliability of the process werestudied by determining the repeatability of the quantificationresults for all target analytes under the described conditionsusing six samples (119899 = 6) The relative standard deviations(RSDs) were lower than 84 in all cases indicating a

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 19: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

4 Journal of Analytical Methods in Chemistry

Table 2 Mass spectrometer parameters for the determination of target analytes

Compound Precursor ion(mz)

Capillary voltage(Ion mode)

Quantification ionmz(collision potential V)

Quantification ionmz(collision potential V)

E3 2872 minus65V (ESI minus) 1710 (37) 1452 (39)E2 2712 minus65V (ESI minus) 1451 (40) 1831 (31)EE 2952 minus60V (ESI minus) 1450 (37) 1589 (33)E1 2692 minus65V (ESI minus) 1450 (36) 1430 (48)DES 2671 minus50V (ESI minus) 2371 (29) 2511 (25)TES 2892 38V (ESI +) 1870 (18) 1040 (21)MGA 3855 30V (ESI +) 2673 (15) 2242 (30)NOR 3132 38V (ESI +) 1090 (26) 2451 (18)

0

500

1000

1500

2000

2500

E3 E2 EE

Peak

area

Cartridge optimizationOASIS HLB pH = 5

OASIS HLB pH = 8

OASIS HLB pH = 11SepPak C18 pH = 5

SepPak C18 pH = 8

SepPak C18 pH = 11BondElut ENV pH = 5

BondElut ENV pH = 8

BondElut ENV pH =11

Figure 1 Optimization of SPE cartridges

strength and sample volume over extraction process Theexperimental design was obtained using Statgraphics Plussoftware 51 and the statistics study was done with IBM SPSSStatistics 19 We assessed two levels and three parameters pH(3 and 8) ionic strength (0 and 30 of NaCl) and samplevolume (50 and 250mL) to obtain the influence of eachparameter and the variable correlation to each other In thisstudy it is observed that the ionic strength and sample volumehad the major influence on the recoveries of the analytesFor that a 32 factorial design to optimize these two variablesat three levels per parameter (0 15 and 30 of NaCl forionic strength and 50 100 y 250mL for sample volume) wasused Figure 2 shows the response surface obtained for theestriol and 17120572-ethinylestradiol The results obtained showedthat an increment of the ionic strength did not producean increase in the response area of the compound and theoptimum volume was 250mL Because of that a solutionwithout salt addition and 250mL of sample volume waschosen Finally the desorption volume (1mLofmethanol and2mL of methanol in one and two steps) and wash-step (5mL

ofMilli-Q water and 5mL ofMilli-Q water with 5 and 10 ofmethanol vv) were assayed to complete the optimization ofthe SPE process The optimum values were 2mL of methanolin one step and 5mL of Milli-Q water without methanolrespectively

In accordance with the obtained results the optimumconditions for SPE procedure were SepPak C

18cartridge

250mL of sample at pH = 8 and 0 of NaCl desorptionwith 2mL of methanol in one step and wash step with5mL of Milli-Q water In these conditions we achieved apreconcentration factor of 125 In Figure 3 a chromatogramwith the optimum conditions is shown where the peaksof all compounds in their corresponding transitions can beobserved

32 Analytical Parameters Because of the SPE optimizationthat was done only with fluorescent compounds (estriol 17120573-estradiol and 17120572-ethinylestradiol) it was necessary to studythe recoveries of all the hormonal compounds using theoptimized SPE-UHPLC-MSMSmethod All the compoundsunder study showed good recoveries over 73 except thediethylstilbestrol with a recovery of 507

A calibration curve was used for the quantification ofthe analytes by diluting the stock solution of each analyteinto the samples to concentrations ranging between 1 and100 120583gsdotLminus1 Analysis was conducted by UHPLC-MSMS andlinear calibration plots for each analyte (1199032 gt 099) wereobtained based on their chromatographic peak areas

The limit of detection (LOD) and the limit of quantifi-cation (LOQ) for each compound were calculated from thesignal-to-noise ratio of each individual peak The LOD wasdefined as the lowest concentration that gave a signal-to-noiseratio that was greater than 3 The LOQ was defined as thelowest concentration that gave a signal to noise ratio that wasgreater than 10The LODs ranged from015 to 935 ngsdotLminus1 andthe LOQs ranged from 049 to 3118 ngsdotLminus1

The performance and reliability of the process werestudied by determining the repeatability of the quantificationresults for all target analytes under the described conditionsusing six samples (119899 = 6) The relative standard deviations(RSDs) were lower than 84 in all cases indicating a

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 20: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Journal of Analytical Methods in Chemistry 5

EstriolPe

ak ar

ea

Ionic strength( of NaCl) Sample volume (mL)

1700

1600

1500

1400

1300

1200

1100

10000

1020

30 50 100 150200 250

(a)

Peak

area

Ionic strength( of NaCl) Sample volume (mL)

1600

1400

1200

1000

010

2030 50 100 150

200

600

800

250

17120572-ethinylestradiol

(b)

Figure 2 Effect of ionic strength and sample volume on the SPE extraction for estriol and 17120572-ethinylestradiol

ESminus(diethylstilbestrol)

ESminus(17120572-ethinylestradiol)

ESminus(17120573-estradiol)

ESminus(estrone)

ESminus(estriol)

ES+(norgestrel)

ES+(testosterone)

ES+(megestrol)

005

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

0

100

()

1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

05 1 15 2 25 3 35 4 45

Figure 3 MRM chromatograms of a spiked sample (250 120583gsdotLminus1) with all analytes after SPE process

good repeatability Table 3 shows the analytical parametersobtained for all compounds analysed

33 Matrix Effect Despite the high sensitivity and lowchemical noise in UHPLC-MSMS systems the sample com-position has a great influence on the analyte signal [22] To

evaluate the relative signal enhancement or suppression inthe samples the algorithm by Vieno et al [23] was used asfollowing

As minus (Asp minus Ausp)As

times 100 (1)

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 21: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

6 Journal of Analytical Methods in Chemistry

0

50

100

150

200

250

300

DES TES EE E1 E2 E3 MGA NOR

WWTP 1

02468

10

TES

Testosterone

02468

10

TESCon

cent

ratio

n (n

gmiddotLminus1)

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(a)

WWTP 2

020406080

100120140160

DES TES EE E1 E2 E3 MGA NOR

Con

cent

ratio

n (n

gmiddotLminus1)

Influent May 99840012Effluent May 99840012

Influent Aug 99840012Effluent Aug 99840012

(b)

Figure 4 Concentrations of target compounds in sewage samples from both wastewater treatment plants (WWTPs)

Table 3 Analytical parameters for the SPE-UHPLC-MSMS method

Compound RSDa () 119899 = 6 LODb (ngsdotLminus1) LOQc (ngsdotLminus1) Recovery () 119899 = 6 Matrix effect ()E3 653 935 312 805 plusmn 53 296E2 837 253 844 897 plusmn 75 133EE 725 051 171 906 plusmn 65 minus126E1 681 260 866 787 plusmn 54 154DES 693 064 214 507 plusmn 35 448TES 677 149 495 838 plusmn 57 171MGA 718 015 049 737 plusmn 53 135NOR 738 211 704 889 plusmn 65 172aRelative standard derivationbDetection limits calculated as signal-to-noise ratio of three timescQuantification limits calculated as signal-to-noise ratio of ten times

where As corresponds to the peak area of the analyte in purestandard solution Asp to the peak area in the spiked matrixextract and Ausp to the matrix extract This procedure wasapplied to an effluent sample assuming that all matrices willbehave in the same way

Suppression effect between 13 and 17 was observed forestrone testosterone norgestrel and megestrol acetate Forestriol 17120573-estradiol and diethylstilbestrol the signal sup-pressions were very low under 5 Only 17120572-ethinylestradiolshowed a signal enhancement of 126 The results obtainedare showed in Table 3 and they are in accordance with thosereported in similar studies [19 24]

34 Analysis of Selected Compounds in Wastewater Sam-ples To check the efficiency of the developed method itwas applied to determination of target analytes in differentwastewater samples from two WWTPs of the island of GranCanaria (Spain) Figure 4 shows the results obtained Itcan be observed that in the WWTP 1 not all compoundswere detected only diethylstilbestrol and testosterone inconcentration that ranging between 35 and 300 ngsdotLminus1 and12 and 995 ngsdotLminus1 respectively for influent samples The

concentrations of diethylstilbestrol at the effluent increasedin the first sampling and diminished in the second Thebehaviour of testosterone in the effluent samples was theopposite

However for WWTP 2 a higher number of compoundswere detected For the influents samples the highest con-centrations were between 100 and 140 ngsdotLminus1 for estriol anddiethylstilbestrol while the rest of compounds (testosteroneestrone and 17120573-estradiol) were detected at concentrationsbetween 20 and 40 ngsdotLminus1 The concentrations at the effluentfor diethylstilbestrol diminished up to 110 ngsdotLminus1 and 5 ngsdotLminus1for testosterone The rest of compounds were not detectedat the effluent samples Only the concentration of norgestrel(about 6 ngsdotLminus1) increased during the wastewater treatmentprocess

4 Conclusions

An analytical method for the simultaneous extraction pre-concentration and determination of oestrogens (estrone17120573-estradiol estriol 17120572-ethinylestradiol and diethylstilbe-strol) androgens (testosterone) and progestogens (norgestrel

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 22: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Journal of Analytical Methods in Chemistry 7

and megestrol acetate) in wastewater matrices has beenoptimized and developed The method used was solid phaseextraction (SPE) for the extractionpreconcentration step andit was combined with UHPLC-MSMS The limits of detec-tion reachedwere between 015 to 935 ngsdotLminus1 In addition themethodpresented high recoveries up to 90 for themajorityof compounds and RSD lower than 9

The application of the method to samples from two dif-ferent WWTPs showed that the concentrations of hormonesfound ranged from 5 to 300 ngsdotLminus1 and some of them(diethylstilbestrol and testosterone) were detected in all thewastewater samples and other like estrone or 17120573-estradiolonly in some samples In view of the obtained resultsabout influent and effluent samples it can be determinedthat the membrane bioreactor system is quite effective todegrade these compounds However it is difficult to obtaina conclusion about the activate sludge treatment effectivityowing to the small quantity of compounds detected

Acknowledgment

This work was supported by funds providds by the SpanishMinistry of Science and Innovation Research Project CTQ-2010-20554

References

[1] T T Pham and S Proulx ldquoPCBs and PAHs in the Montrealurban community (Quebec Canada) wastewater treatmentplant and in the effluent plume in the St Lawrence riverrdquoWaterResearch vol 31 no 8 pp 1887ndash1896 1997

[2] R Rosal A Rodrıguez J A Perdigon-Melon et al ldquoOccurrenceof emerging pollutants in urban wastewater and their removalthrough biological treatment followed by ozonationrdquo WaterResearch vol 44 no 2 pp 578ndash588 2010

[3] C Baronti R Curini G DrsquoAscenzo A Di Corcia A Gentiliand R Samperi ldquoMonitoring natural and synthetic estrogensat activated sludge sewage treatment plants and in a receivingriver waterrdquo Environmental Science and Technology vol 34 no24 pp 5059ndash5066 2000

[4] European Commission ldquoDirective 2008105EC of theEuropean Parliament and of the Council of 16 December2008 on environmental quality standards in the field ofwater policy amending and subsequently repealing Councildirectives 82176EEC 83513EEC 84156EEC 84491EEC86280EEC and amending Directive 200060ECrdquo OfficialJournal of the European Communities vol L348 2008

[5] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[6] G G Ying R S Kookana and Y J Ru ldquoOccurrence andfate of hormone steroids in the environmentrdquo EnvironmentInternational vol 28 no 6 pp 545ndash551 2002

[7] F Stuer-Lauridsen M Birkved L P Hansen H C HoltenLutzhoslashft and B Halling-Soslashrensen ldquoEnvironmental risk assess-ment of human pharmaceuticals in Denmark after normaltherapeutic userdquo Chemosphere vol 40 no 7 pp 783ndash793 2000

[8] D Barcelo and M Petrovic Analysis Fate and Removal ofPharmaceuticals in the Water Cycle Elsevier 2007

[9] A L Filby T Neuparth K L Thorpe R Owen T S Gallowayand C R Tyler ldquoHealth impacts of estrogens in the envi-ronment considering complex mixture effectsrdquo EnvironmentalHealth Perspectives vol 115 no 12 pp 1704ndash1710 2007

[10] S K Khanal B Xie M L Thompson S Sung S K Ongand J Van Leeuwen ldquoFate transport and biodegradation ofnatural estrogens in the environment and engineered systemsrdquoEnvironmental Science and Technology vol 40 no 21 pp 6537ndash6546 2006

[11] JW Birkett and J N Lester Endocrine Disrupters inWastewaterand Sludge Treatment Processes Lewis Publishers and IWAPublishing 2003

[12] J Y Hu X Chen G Tao and K Kekred ldquoFate of endocrinedisrupting compounds in membrane bioreactor systemsrdquo Envi-ronmental Science and Technology vol 41 no 11 pp 4097ndash41022007

[13] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDetermination of alkylphenol polyethoxylates bisphenol-A17120572-ethynylestradiol and 17120573-estradiol and its metabolites insewage samples by SPE and LCMSMSrdquo Journal of HazardousMaterials vol 183 no 1ndash3 pp 701ndash711 2010

[14] M Petrovic E Eljarrat M J Lopez de Alda and D BarceloldquoRecent advances in the mass spectrometric analysis relatedto endocrine disrupting compounds in aquatic environmentalsamplesrdquo Journal of Chromatography A vol 974 no 1-2 pp 23ndash51 2002

[15] D Matejıcek and V Kuban ldquoHigh performance liquidchromatographyion-trap mass spectrometry for separationand simultaneous determination of ethynylestradiol gestodenelevonorgestrel cyproterone acetate and desogestrelrdquo AnalyticaChimica Acta vol 588 no 2 pp 304ndash315 2007

[16] M J Lopez De Alda and D Barcelo ldquoDetermination of steroidsex hormones and related synthetic compounds considered asendocrine disrupters in water by liquid chromatography-diodearray detection-mass spectrometryrdquo Journal of ChromatographyA vol 892 no 1-2 pp 391ndash406 2000

[17] M J Lopez De Alda S Dıaz-Cruz M Petrovic and DBarcelo ldquoLiquid chromatography-(tandem)mass spectrometryof selected emerging pollutants (steroid sex hormones drugsand alkylphenolic surfactants) in the aquatic environmentrdquoJournal of Chromatography A vol 1000 no 1-2 pp 503ndash5262003

[18] H C Zhang X J Yu W C Yang J F Peng T Xu and D QYin ldquoMCX based solid phase extraction combined with liquidchromatography tandem mass spectrometry for the simultane-ous determination of 31 endocrine-disrupting compounds insurface water of Shanghairdquo Journal of Chromatography B vol879 no 28 pp 2998ndash3004 2011

[19] T Vega-Morales Z Sosa-Ferrera and J J Santana-RodrıguezldquoDevelopment and optimisation of an on-line solid phaseextraction coupled to ultra-high-performance liquidchromatography-tandem mass spectrometry methodologyfor the simultaneous determination of endocrine disruptingcompounds in wastewater samplesrdquo Journal of ChromatographyA vol 1230 no 1 pp 66ndash76 2012

[20] S Masunaga T Itazawa T Furuichi et al ldquoOccurrence ofestrogenic activity and estrogenic compounds in the Tama riverJapanrdquo Environmental Science vol 7 no 2 pp 101ndash117 2000

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 23: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

8 Journal of Analytical Methods in Chemistry

[21] Scifinder Chemical Abstracts Service Columbus Ohio USApKa calculated using Advanced Chemistry Development(ACDLabs) Software V1102 2013 httpsscifindercasorg

[22] S Gonzalez D Barcelo and M Petrovic ldquoAdvanced liquidchromatography-mass spectrometry (LC-MS)methods appliedto wastewater removal and the fate of surfactants in theenvironmentrdquo Trends in Analytical Chemistry vol 26 no 2 pp116ndash124 2007

[23] N M Vieno T Tuhkanen and L Kronberg ldquoAnalysis ofneutral and basic pharmaceuticals in sewage treatment plantsand in recipient rivers using solid phase extraction and liquidchromatography-tandem mass spectrometry detectionrdquo Jour-nal of Chromatography A vol 1134 no 1-2 pp 101ndash111 2006

[24] V Kumar N Nakada M Yasojima N Yamashita A CJohnson and H Tanaka ldquoRapid determination of free andconjugated estrogen in different water matrices by liquidchromatography-tandem mass spectrometryrdquo Chemospherevol 77 no 10 pp 1440ndash1446 2009

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 24: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 568614 8 pageshttpdxdoiorg1011552013568614

Research ArticleRemoval Efficiency and Mechanism of Sulfamethoxazole inAqueous Solution by Bioflocculant MFX

Jie Xing Ji-Xian Yang Ang Li Fang Ma Ke-Xin Liu Dan Wu and Wei Wei

State Key Lab of Urban Water Resource and Environment School of Municipal and Environmental EngineeringHarbin Institute of Technology Harbin 150090 China

Correspondence should be addressed to Ang Li li ang1980yahoocomcn and Fang Ma mafanghiteducn

Received 30 November 2012 Accepted 5 January 2013

Academic Editor Fei Qi

Copyright copy 2013 Jie Xing et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Although the treatment technology of sulfamethoxazole has been investigated widely there are various issues such as the high costinefficiency and secondary pollution which restricted its application Bioflocculant as a novel method is proposed to improvethe removal efficiency of PPCPs which has an advantage over other methods Bioflocculant MFX composed by high polymerpolysaccharide and protein is themetabolism product generated and secreted byKlebsiella sp In this paperMFX is added to 1mgLsulfanilamide aqueous solution substrate and the removal ratio is evaluated According to literatures review forMFX absorption ofsulfanilamide flocculant dosage coagulant-aid dosage pH reaction time and temperature are considered as influence parametersThe result shows that the optimum condition is 5mgL bioflocculant MFX 05mgL coagulant aid initial pH 5 and 1 h reactiontime and the removal efficiency could reach 6782 In this condition MFX could remove 5327 sulfamethoxazole in domesticwastewater and the process obeys Freundlich equation R2 value equals 09641 It is inferred that hydrophobic partitioning is animportant factor in determining the adsorption capacity of MFX for sulfamethoxazole solutes in water meanwhile some chemicalreaction probably occurs

1 Introduction

In recent decades the use of pharmaceutical and personalcare products (PPCPs) has increased dramatically [1 2]They are members of a group of chemicals newly classi-fied as organic microcontaminants in water after pesticideand endocrine disrupting compounds which stably exist innature have properties of being hard-biodegraded bioaccu-mulation and long-range hazardous posing far-reaching andunrecoverable hazard on ecosystem [3ndash5] The presence ofPPCPs of emerging concern as increasing evidence suggeststheir harmfulness [6] Antibiotic medicine sulfamethoxazolefeatures classic PPCPs with very low removal ratio in watertreatment and high frequency to be detected In recentdecades although the consume of sulfamethoxazole has beenreduced it is the most popular germifuga in animal foodproduction [7] It is reported that SMX applied in veterinarydirectly discharges into the aquatic environment which hashigh toxicity [8] Therefore there have been large amountof studies on sulfamethoxazole However most attention

has been focused on identification fate and distribution ofPPCPs in municipal wastewater treatment plants [9 10] It issignificant to develop treatmentmethod to remove SMXThecommonly used treatment methods include advanced oxida-tion process adsorption and membrane technology [11ndash13]Bioflocculation absorption method has several advantagesover other methods such as going green being environmen-tally protective no second pollution and being biodegrad-able [14] What is more bioflocculation has been provedto be highly effective and wildly applied and yet there isno published research on bioflocculation removal of PPCPsThus it is meaningful to study the removal of PPCPs bybioflocculation Bioflocculant MFX is a metabolized produc-tion with good flocculant activity generated and secreted byKlebsiella sp into the extracellular environment composedof macromolecular polysaccharide and protein In this studybased on its physical and chemical property the effectiveingredient of MFX is extracted by water abstraction andalcohol precipitation transformed into dry powder And thenthe removal efficiency andmechanismof sulfamethoxazole in

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 25: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

2 Journal of Analytical Methods in Chemistry

aqueous environment are researchedThe study aims at devel-oping an effective treatmentmethod of sulfamethoxazole andexpanding the applied range of bioflocculation

2 Materials and Methods

21 Strains and Media

211 Bioflocculant-Producing Bacterium Strain J1 Klebsiellasp The strain was screened by our laboratory from activatedsludge in municipal wastewater treatment plants and pre-served in China General Microbiological Culture CollectionCenter (CGMCC number 6243)

212 Inclined Plane Medium (gL) Peptone 10 NaCl 5 beefextract 3 agar 15sim18 water 1000mL pH 70sim72 Flocuclantfermentationmedium (gL) glucose 10 yeast extract 05 urea05 MgSO

4sdot7H2O 02 NaCl 01 K

2HPO45 KH

2PO42 H2O

1000mL pH 72sim75

22 Methods

221 Assay Methord Flocculating rate 50 g chemically purekaolin clay 1000mL tap water and 15mL 10 CaCl

2liquid

are added into a beaker pH is adjusted to 72 by addingNaOH then 10mL flocculant is added compared withcontrol without flocculant addition Flocculator is appliedduring the experiment after 40 s fast mixing and changedinto slow mixing for 4 minutes after 20min settling andthe absorbance of the supernatant is measured under 550 nmby 721 UV spectrometer [15] The flocculation efficiency iscalculated as follows

flocculation efficiency = (119860 minus 119861)119860times 100 (1)

where 119860 is turbidity of the supernatant in control (lighttransmittance) 119861 is turbidity of the supernatant in sample

The removal efficiency of sulfamethoxazole is calculatedby the following equation

remove efficiency = (119862 minus 119863)119862times 100 (2)

where 119862 is the concentration in control and 119863 is thesulfamethoxazole concentration after treatment

Polysaccharide measurement Phenol-sulphuric acidmethod [16]Protein measurement Coomassie light blue [16]

222 Bioflocculant Preparation Add 2x volume absolutealcohol (precooled under 4∘C) to fermentation liquid andfilter and collect the white flocs after mixing Add 1x volumeabsolute alcohol to filtered liquid and then collect the whiteflocs again Add small amount of DI water to collectedflocs after uniformly dissolving freeze the flocculants in theultralow temperature freezer for 24 h and then put them intofreeze drying to change the flocculants into dry powder

223 Chromatographic Condition Chromatographic col-umn C18 (250 lowast 46mm 5 um) mobile phase is formicacid water Acetonitrlle (60 40VV) flow rate 10mLminsample size 10 120583L column temperature 30∘C wave length265 nm [17]

224 Impact Factor Experiment of Sulfamethoxazole RemovalEfficiency Add flocculants into 1mgL sulfamethoxazotheliquid with dosage 0mL 1mL 3mL 5mL 7mL and 9mLset the coagulant aids dosage as 0mL 05mL 1mL 15mLand 2mL adjust pH value to 4 5 6 7 and 8 under 5∘C15∘C 25∘C 35∘C 45∘C and 55∘C change the reaction timeas 0 h 025 h 05 h 075 h 1 h 2 h 4 h 6 h 8 h 10 h and 12 hcalculate the removal rate

225 Orthogonal Test of Sulfamethoxazole Removal by Bio-flocculants Based on the preliminary obtained optimumcondition flocculant dosage coagulant-aid dosage pH reac-tion time and temperature are considered as influencingparameters The design of experiment is shown in Table 1

226 Adsorption Isotherm Experiment of SulfamethoxazoleRemoval by Bioflocculants Mix the flocculant MFX and sul-famethoxazole with initial concentration as 08mgL 1mgL12mgL 14mgL 16mgL and 18mgL separately underdifferent temperature condition as 15∘C 35∘C put on 140 rpmshaking table with constant temperature conduct adsorptionisotherm experiment and adsorption time is 1 h

3 Results and Discussion

31 Analysis of Flocculent Active Ingredients The strain J1was short rod-shaped cream-colored viscous smooth andGram-positive J1 was identified as Klebsiella sp on the basisof themorphological characteristics and 16S rDNA sequenceThe J1 showed a high yield of flocculant and good flocculationactivity toward kaolin suspension The active ingredientsof bioflocculant MFX produced by J1 distributed mainly inthe supernatant after the first centrifugation of fermentationbroth that is to say the flocculation active extracellularsecretions remain freely in fermentation broth (Figure 1)Flocculation ratio after first centrifugation appeared nega-tively which proved that the J1 itself was not responsiblefor the flocculation The addition of cell suspension leads tothe increasing turbidity of raw water After ultrasonic crush-ing and centrifugation bacteria cells were broken and theintercellular content went into the supernatant the negativityof flocculation ratio showed the fact that the intercellularcontent may not have flocculation effect What is morefermentation broth without inoculation has relatively highflocculation ratio and it may be caused by the flocculationeffect and coagulation aid effect of the phosphate or otherinorganic salts Thus we may reach the conclusion that theflocculant active ingredient is the metabolized productionin the meantime the growth medium also contributes to theflocculation By the isolation and purification of flocculationactive ingredients removing disturbance of growth medium

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 26: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Journal of Analytical Methods in Chemistry 3

1 2 3 4 5 6

minus300

minus250

minus200

minus150

minus100

minus50

0

50

100

Floc

culat

ing

rate

()

Sample

Figure 1 Distribution of flocculent active ingredients

Table 1 Factors and levels of orthogonal test

Levels 119860

pH

119861

Flocculantdosage (mL)

119862

Coagulantaid dosage

(mL)

119863

Reactiontime (h)

1 5 2 0 052 6 5 02 13 7 8 05 15

Table 2 Qualitative analysis of flocculent active ingredients

Reaction type Analytical method Phenomenon

PolysaccharideMolish reaction +

Anthrone reaction +Seliwanoff reaction minus

ProteinNinhydrin reaction +Biuret reaction +

Xanthoprotein reaction +

a further conclusion may be reached that is the active ingre-dient is the secondary metabolites of bacteria fermentation(extracellular polymeric substances (EPS))

Table 2 presents MFX that has apparent results in thesaccharides and protein chromogenic reactions According toTable 2 we can conclude qualitatively that the major ingredi-ents of the flocculant produced by J1 are polysaccharides andprotein the polysaccharides content is 00656mgmL andthe protein content is 01021mgmL

After the enzymatic digestion of EPS polysaccha-rides were removed while proteins remained The pro-teins accounted for 1505 (cellulase) 619 (120572-amylase)and 114 (120573-amylase) of the flocculation activity On thecontrary proteins were removed while polysaccharidesremained EPS has no flocculent activity (Table 3) Obviousdecrease in flocculation activity was observed after theflocculant MFX was exposed at 70∘C for 20min indicatingthat it was low thermostable This implies that the active

Table 3 Enzymatic digestion of flocculent active ingredients

Reaction type Enzym Flocculation rate afterenzymatic digestion Floc

PolysaccharideCellulase 1505 Small120572-amylase 6190 Big120573-amylase 114 Small

Protein

Trifluoroaceticacid Negative None

Pepsase Negative NoneTrypsin Negative None

constituents in MFX were proteins and polysaccharides andproteins dominant accounted for the flocculation activity

32 The Impact Factors on Removal Efficiency of Sulfamethox-azole by MFX Five parameters pH value flocculant dosagecoagulation aid ratio flocculation time and temperature aremeasured to see the effects of these factors on sulfamethoxa-zole removal efficiency Along with the changes of pH valuethe removal efficiency increases firstly then decrease andchanges sharply from where we could know that pH doesaffect removal ratio a lot It is shown in Figure 2(a) thatbetween pH 4 and 5 the removal efficiency increases alongwith pH increment When pH is 5 MFX possesses thestrongest flocculation capacity and the highest flocculationefficiency which is 672 Between pH 6 and 8 the removalefficiency falls steeply when pH is 8 and the removal effi-ciency is only 161The result demonstrated that the biofloc-culant has higher removal efficiency on sulfamethoxazole inthe acidic condition while the alkali condition results in rel-atively poor removal efficiency Figure 2(b) shows that alongwith the increase of flocculant dosage the removal efficiencyincreases firstly then decreases and changes acutely Whenflocculant dosage varies within the range from 1mL to 5mLthe removal efficiency improved with the increasing dosageWhen flocculant dosage is 5mL the optimum removalefficiency is obtained which is 5789 As seen in Figure 2(c)the dosage of coagulant aid also has impact on the removalefficiency Increasing volume ratio of coagulant aid leads toincreasing removal efficiency When coagulant aid dosage is01 times of flocculation dosage which is 05mL more than50 removal efficiency is reached Afterwards the incrementof coagulant aid dosage decreases flocculation capability andremoval efficiency In the meantime the removal efficiencyis around 20 without coagulant aid addition which provesthat bioflocculant could remove sulfamethoxazole withoutcoagulant aid Figure 2(d) shows that the removal efficiencyincreases firstly then decreases with the change of tempera-ture but within narrow fluctuation rangeWhen temperatureis between 5∘C and 25∘C the removal efficiency increasesslowly When temperature is 35∘C the strongest flocculationcapability is obtained and the highest removal efficiency isreached which is 6720The removal efficiency decreases onthe temperature of 45∘C and 55∘C According to Figure 2(e)the removal efficiency increases exponentially within the first30 minutes after 30 minutes the increment slows down and

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 27: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

4 Journal of Analytical Methods in Chemistry

0

10

20

30

40

50

60

70

80Re

mov

alra

te(

)

pH4 5 6 7 8

(a)

Rem

oval

rate

()

1 3 5 7 9

70

MFX dosage (mL)

0

10

20

30

40

50

60

(b)

Rem

oval

rate

()

0

10

20

30

40

50

60

0 05 1 15 2CaCl2 dosage (mL)

(c)

Rem

oval

rate

()

70

0

10

20

30

40

50

60

5 15 25 35 45 55Temperature (∘C)

(d)

Rem

oval

rate

()

0 1 2 3 4 5 6 7 8 9 10 11 1235

40

45

50

55

60

65

70

Time (h)

(e)

Figure 2The influence of ecological factor on removal rate (a) is the influence of pH (b) is the influence of MFX dosage (c) is the influenceof CaCl

2

dosage (d) is the influence of temperature (e) is the influence of time on removal rate

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 28: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Journal of Analytical Methods in Chemistry 5

remains the same after 1 hour reaching equilibrium Thisis because of that a large amount of adsorbate exists inthe liquid in the beginning of the reaction and is adsorbedquickly by adsorbent With the occupation of the adsorptionsites adsorption quantity inclines slowly After equilibrium isreached the adsorption quantity remains constantly

In conclusion the optimum flocculation condition ispH 5 flocculant dosage 5mL coagulant aid dosage 05mLflocculant reaction time 1 h and temperature 35∘CUnder thiscondition the highest removal efficiency is reached which is6782 It is reported that the removal efficiency using con-ventional water treatment process including preoxidationcoagulation and sand filtration is 36 [18] and the removalefficiency by microelectrolysis Fentonis is 655 [19] It canbe seen that bioflocculant is obviously more efficient thannormal treatment

33 The Removal Efficiency of Sulfamethoxazole in DomesticWastewater by MFX In order to evaluate the removal effectof bioflocculantMFXon sulfamethoxazole in actual wastewa-ter domestic wastewater is used with sulfamethoxazole con-centration as 2326 ugL 9 sets of experiments are conductedaccording to the orthogonal design table L9 (34) and resultsare shown in Table 4

As is shown in Table 4 according to average valueanalysis optimum flocculation condition is the combinationof A1B3C2D2 which is pH 5 flocculant dosage 8mL coag-ulant aid dosage 02mL and reaction time 1 h It has beenproved that under this condition the removal efficiency ofsulfamethoxazole is 5327

By comparing the extremums wemay reach a conclusionthat the effect degrees of factors obey the following orderRA gt RB gt RC gt RD That is to say pH value affectsmostly followed by flocculant dosage coagulant aid dosageand reaction time This is because that the dissociationof flocculant occurs within a certain pH range ProperpH value could increase the dissociation degree lead to ahigher charge density of flocculant benefits the spreading ofthe flocculant molecules and facilitates the bridging actionof the bioflocculant Thus pH value plays a critical role[20] When the flocculant dosage is relatively low earlyadsorption saturation may be reached the removal efficiencyof contaminants decreases When flocculant dosage is highextraflocculant weakens the bridging effect due to adsorptionsites overlapping and finally affects the removal efficiency ofspecific contaminantThus proper flocculant dosage plays animportant role in affecting removal efficiency Some studiesshow thatmetal ions addition could change the surface chargeof colloids sulfamethoxazole flocs in the water are negativelycharged and when approaching positively charged flocculanthydrolyzates and calcium ions in coagulant aid chargeneutralization occurs on the surface of sulfamethoxazoleand makes the colloidal particles to sediment exacerbatingthe collision of colloids and collision between colloids andflocculant integrating a whole group under Van der Waalsrsquoforce finally precipitating from water by gravity [21]

In the research of removal mechanism of sulfamethox-azole aqueous solution the highest removal efficiency is

minus03 minus02 minus01 0 01 0217

175

18

185

19

195

2

205

lg119862119878

(mg

g)

lg119862 (mgL)119882

(a)

minus06 minus05 minus04 minus03 minus02 minus01 02

205

21

215

22

225

lg119862119878

(mg

g)

lg119862 (mgL)119882

(b)

Figure 3 Adsorption isotherms of sulfamethoxazole by MFXadsorbent in 15∘C (a) and 35∘C (b)

more than 60 but in the removal of sulfamethoxazole inwastewater the highest removal efficiency under optimumcondition is only 5327This may be caused by the relativelylow concentration of sulfamethoxazole in wastewater whichis 2326 ugL The limitation of measurement methods maylead to potential systematic errorsOn the other hand domes-tic wastewater has complex component and there existsreversible and irreversible competitions among substratesliming the combination of flocculant and sulfamethoxazoleWhat is more some unknown ions and organic compoundsmay also decrease the removal efficiency

34 The Mechanism of Sulfamethoxazole in Aqueous Solutionby MFX The dry power of MFX is white sparses andreticulate while the aqueous solution is milky white ropyand turbid The material of MFX adsorbent is glycoprotein

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 29: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

6 Journal of Analytical Methods in Chemistry

Table 4 Orthogonal test result and visual analysis

Tests119860

pH 119861

Flocculant dosage (mL)119862

Coagulant aid dosage (mL)119863

Reaction time (h) Removal efficiency ()

1 1 1 1 1 40642 1 2 2 2 48383 1 3 3 3 50134 2 1 2 2 36915 2 2 3 1 30266 2 3 1 3 44277 3 1 3 2 29868 3 2 1 3 35039 3 3 2 1 4170Average 1 46383 35803 39980 37533Average 2 37147 37890 42330 40837Average 3 35530 45367 36750 40690Variance 10853 9564 5580 3304

which has hydrophobicity and displays a wide range ofsorption behavior for hydrophobic organic compounds inaqueous solutions [22] The adsorption isotherms of sul-famethoxazole on MFX adsorbents are presented in Fig-ure 3 and Table 5 Adsorption data are fitted to Freundlichisotherm model which is the most widely used modelsfor describing adsorption phenomena in aqueous solutionsThe Freundlich isotherm model is an empirical equationaccurate for describing adsorption in aqueous solutions atlow solute concentrations Expressions and interpretationsare as follows The maximum adsorption capacity of theadsorbent is represented by 119870

119865(mgg) while 119899 is constant

which is indicative of the adsorption energy and intensity

119862119878= 119870119865sdot 1198621119899

119882

lg119862119878=1

119899lg119862119882+ lg119870

119865

(3)

where 119862119878is mass concentration in solid phase after adsorp-

tion equilibrium (mgg) 119862119882is concentration in liquid phase

after adsorption equilibrium (mgL)The results show that MFX exhibited high-adsorption

capacities for sulfamethoxazole in water A maximumadsorption capacity (119870

119891) of 1766445mgg was obtained with

MFX in 35∘C Compared Figure 3(a) with Figure 3(b) itcan be perceived that linear correlation is marked in 35∘CAccording to 119899 value it is known that under this temperaturethe adsorptive property of MFX to sulfamethoxazole is highHowever MFX has poorer adsorption efficiency in 15∘C 1198772value is only 0882 while n value is lower than the former

This is due to the effect of temperature on chemicalreaction and molecular movement which finally promoteor restrain flocculent effect On the one hand providingappropriate temperature colloidal particle is bombardedintensively by molecules of flocculation to form a whole Iftemperature is excessively low molecular movement slowsdown and reaction rate lessens leading to bad adsorptive

Table 5 Freundlich isotherm parameters at different temperature

T (∘C) Freundlich equation 119870119865

1198772

119899

15 119910 = 0483119909 + 19146 821486 08820 20735 119910 = 03748119909 + 22471 1766445 09641 318

property On the other hand some active groups betweenbioflocculant and sulfamethoxazole start the chemical reac-tion to separate out of aqueous solution system Whatis more when hydrophobic chain polymer-bioflocculationMFX comes into sulfamethoxazole aqueous solution systemwith the help of appropriate pH and Ca2+ sulfamethoxazolebecomes unstable rapidly passing into flocculation phase

Driven by such mechanism the adsorption onMFX doesnot rely on a high porosity and a resultant high specificsurface area to reach a high adsorption capacity as formost activated carbon and polymeric adsorbents This resultimplies that hydrophobic partitioning is an important factorin determining the adsorption capacity of MFX for sul-famethoxazole solutes in water meanwhile some chemicalreaction probably occurs

4 Conclusion

Thiswork demonstrates the efficient removal of sulfamethox-azole fromwater using bioflocculantMFX as adsorbentsThefindings are summarized as follows

(1) The active flocculent constituents of MFX are EPSwhich is composed by polysaccharides and proteinsfermented by J1 Proteins mainly accounted for theflocculation activity

(2) The MFX displays great sorption behavior for sul-famethoxazole in aqueous solutions The optimumcondition is 5mgL bioflocculant 05mgL coagulant

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 30: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Journal of Analytical Methods in Chemistry 7

aid initial pH 5 and 1 h reaction time and theremoval efficiency could reach 6782

(3) Using MFX the removal rate of sulfamethoxazolein domestic wastewater can reach 5327 The effectsize of ecological factor is as follow pH gt flocculantdosage gt coagulant aid gt reaction time

(4) It is efficient for MFX to remove sulfamethoxazolein aqueous environment in 35∘C And the processobeys Freundlich equation 1198772 value equals 09641 Itis inferred that hydrophobic partitioning is an impor-tant factor in determining the adsorption capacity ofMFX for sulfamethoxazole solutes in water

The study shows that bioflocculation MFX can be usedas an efficient alternative adsorbent for the removal ofsulfamethoxazole in water with high-adsorption capacitiesobserved in actual wastewater Further studies are underwayto make mathematical models of the relationship betweenflocculant and contaminant When many PPCPs coexist theresearch on removal efficiency with bioflocculant is moresignificant

Acknowledgments

This work was supported by Grants from the National HighTechnology Research and Development Program of China(863 Program) (no 2009AA062906) the National CreativeResearch Group from the National Natural Science Founda-tion of China (no 51121062) the National Natural ScienceFoundation of China (Nos 51108120 and 51178139) the KeyProjects of National Water Pollution Control and Manage-ment of China (nos 2012ZX07212-001 and 2012ZX07201-003) and the State Key Lab of Urban Water Resource andEnvironmentHarbin Institute of Technology (nos 2010TX03and 2010DX09)

References

[1] C G Daughton and T A Ternes ldquoPharmaceuticals andpersonal care products in the environment agents of subtlechangerdquo Environmental Health Perspectives vol 107 Supple-ment 6 pp 907ndash938 1999

[2] J Kagle A W Porter R W Murdoch G Rivera-Cancel and AG Hay ldquoBiodegradation of pharmaceutical and personal careproductsrdquo Advances in Applied Microbiology vol 67 pp 65ndash992009

[3] G T Ankley B W Brooks D B Huggett and J P SumpterldquoRepeating history pharmaceuticals in the environmentrdquo Envi-ronmental Science and Technology vol 41 no 24 pp 8211ndash82172007

[4] D W Kolpin E T Furlong M T Meyer et al ldquoPharmaceu-ticals hormones and other organic wastewater contaminantsin US streams 1999-2000 a national reconnaissancerdquo Envi-ronmental Science and Technology vol 36 no 6 pp 1202ndash12112002

[5] A B A Boxall ldquoThe environmental side effects of medicationrdquoEMBO Reports vol 5 no 12 pp 1110ndash1116 2004

[6] E Marco-Urrea J Radjenovic G Caminal M Petrovic TVicent and D Barcelo ldquoOxidation of atenolol propranolol

carbamazepine and clofibric acid by a biological Fenton-likesystem mediated by the white-rot fungus Trametes versicolorrdquoWater Research vol 44 no 2 pp 521ndash532 2010

[7] J Radjenovic C Sirtori M Petrovic D Barcelo and S MalatoldquoSolar photocatalytic degradation of persistent pharmaceuticalsat pilot-scale kinetics and characterization of major intermedi-ate productsrdquo Applied Catalysis B vol 89 no 1-2 pp 255ndash2642009

[8] C Wu A L Spongberg J D Witter M Fang and K PCzajkowski ldquoUptake of pharmaceutical and personal careproducts by soybean plants from soils applied with biosolidsand irrigated with contaminated waterrdquo Environmental Scienceand Technology vol 44 no 16 pp 6157ndash6161 2010

[9] L Hu P M Flanders P L Miller and T J Strathmann ldquoOxi-dation of sulfamethoxazole and related antimicrobial agents byTiO2

photocatalysisrdquo Water Research vol 41 no 12 pp 2612ndash2626 2007

[10] T Polubesova D Zadaka L Groisman and S Nir ldquoWaterremediation by micelle-clay system case study for tetracyclineand sulfonamide antibioticsrdquoWater Research vol 40 no 12 pp2369ndash2374 2006

[11] S Kaniou K Pitarakis I Barlagianni and I Poulios ldquoPhotocat-alytic oxidation of sulfamethazinerdquo Chemosphere vol 60 no 3pp 372ndash380 2005

[12] K M Onesios J T Yu and E J Bouwer ldquoBiodegradationand removal of pharmaceuticals and personal care products intreatment systems a reviewrdquo Biodegradation vol 20 pp 441ndash466 2009

[13] M N Abellan B Bayarri J Gimenez and J Costa ldquoPhotocat-alytic degradation of sulfamethoxazole in aqueous suspensionof TiO

2

rdquo Applied Catalysis B vol 74 no 3-4 pp 233ndash241 2007[14] L L Wang F Ma Y Y Qu et al ldquoCharacterization of a com-

pound bioflocculant produced by mixed culture of Rhizobiumradiobacter F2 and Bacillus sphaeicus F6rdquo World Journal ofMicrobiology and Biotechnology vol 27 no 11 pp 2559ndash25652011

[15] J Xing J Yang F Ma L Wei and K Liu ldquoStudy on the optimalfermentation time and kinetics of bioflocculant produced bybacterium F2rdquo Advanced Materials Research vol 113-114 pp2379ndash2384 2010

[16] J A Dean Langersquos Handbook of Chemistry World PublishingCorporation Singapore 2004

[17] L C Lin ldquoSimultaneous determination of sulfadiazine andsulfamethoxazole residues inmuscle of European Eels (Anguillaanguilla) by HPLCrdquo Fujian Journal of Agricultural Sciences vol26 no 5 pp 697ndash700 2011

[18] W M Shi K Y Liu and W T Ye ldquoThe study on migrationand transfer and removal of sulfamethoxazole in water supplysystemrdquoTechnology ofWater Treatment vol 37 no 6 pp 86ndash892011

[19] T F WanThe study on pretreatment of sulfadiazine in pharma-ceutical wastewater by microelectrolysismdashFenton [MS thesis]Chengdu University of Technology 2011

[20] L L Wang L F Wang and H Q Yu ldquopH dependence of struc-ture and surface properties of microbial EPSrdquo EnvironmentalScience amp Technology vol 46 no 2 pp 737ndash744 2012

[21] X-M Liu G-P Sheng H-W Luo et al ldquoContribution of extra-cellular polymeric substances (EPS) to the sludge aggregationrdquoEnvironmental Science and Technology vol 44 no 11 pp 4355ndash4360 2010

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 31: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

8 Journal of Analytical Methods in Chemistry

[22] J Han W Qiu S W Meng and W Gao ldquoRemovalof ethinylestradiol from water via adsorption on aliphaticpolyamidesrdquoWater Research vol 46 no 17 pp 5715ndash5724 2012

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 32: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 387124 8 pageshttpdxdoiorg1011552013387124

Research ArticlePyrite Passivation by TriethylenetetramineAn Electrochemical Study

Yun Liu1 2 Zhi Dang2 3 Yin Xu1 and Tianyuan Xu1

1 Department of Environmental Science and Engineering Xiangtan University Xiangtan 411105 China2The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of Education Guangzhou 510006 China3Higher Education Mega Center School of Environmental Science and Engineering South China University of TechnologyGuangzhou 510006 China

Correspondence should be addressed to Yun Liu liuyunscut163com

Received 24 November 2012 Accepted 29 December 2012

Academic Editor Fei Qi

Copyright copy 2013 Yun Liu et al This is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The potential of triethylenetetramine (TETA) to inhibit the oxidation of pyrite in H2

SO4

solution had been investigated by usingthe open-circuit potential (OCP) cyclic voltammetry (CV) potentiodynamic polarization and electrochemical impedance (EIS)respectively Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that theinhibition efficiency is more pronounced with the increase of TETA The data from potentiodynamic polarization show that theinhibition efficiency (120578) increases from 4208 to 8098with the concentration of TETA increasing from 1 to 5These resultsare consistent with the measurement of EIS (4309 to 8255)The information obtained from potentiodynamic polarization alsodisplays that the TETA is a kind of mixed type inhibitor

1 Introduction

Pyrite FeS2 is one of the most common sulfide minerals It is

frequently present in tailings waste rock dumps many valu-able mineral raw materials and coal [1] It is easy to be oxi-dized under natural weathering conditions The oxidation ofpyrite results in sulfuric acid and toxic tracemetals formationin acid mine drainage (AMD) which is one of the mostserious environmental problems facing the mining industry[2] That is why many studies have been carried out on themechanism of pyritersquos oxidation during the last six decadesby investigators from different areas such as metallurgy andenvironment science [3ndash9] Now researchers have found thatthe oxygen and ferric iron play a very important role forthe pyritersquos oxidation [10 11] and that some acidophilicmicro-organisms for example Acidithiobacillus ferrooxidans [12]and Leptospirillum ferrooxidans [13] can accelerate the oxida-tion of pyrite greatly According to the knowledge of peoplefor the mechanism of pyrite decomposition if it is no contactbetween pyrite and oxidants (eg O

2and Fe3+) the rate of

pyrite oxidation could be suppressed For years several

techniques have been developed to reduce the oxidation ofsulfide minerals including bactericides [14] neutralization[15 16] and cover treatment [17ndash19] However most of thesetechnologies are costly short-term solutions and difficult toapply

In parallel many researchers have used certain chemicalreagents that can create effective oxygen barriers to protectthe surface of iron sulfide from oxidation For example bothiron phosphate precipitates and silica precipitates have beenshown to suppress pyrite oxidation efficiently However thesetreatments require initial surface oxidation with hydrogenperoxide which is difficult to handle in a real application [2021] Similarly although some passivating agents such as acetylacetone humic acids ammonium lignosulfonates oxalicacid and sodium silicate also have the capability to inhibitpyrite from oxidation these treatments also need peroxida-tion and the coating with oxalic acid requires a temperaturecontrol at 65∘C [22] In addition Elsetinow et al [23] haveconcluded that the formation of a passivating layer on thepyrite surface after exposure to the lipid could suppress pyriteoxidation by either interrupting the advection of aqueous

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 33: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

2 Journal of Analytical Methods in Chemistry

oxidants or the electron transfer between oxidants and thepyrite Using the property of formation of strong insolublechelating complex with Fe3+ Lan et al [24] have investigatedthe possibility of using 8-hydroxyquinoline as a passivatingagent and they demonstrated that the oxidation rates ofpyrite could be reduced remarkably In recent years our lab-oratory has also developed a new passivating agent triethyl-enetetramine (TETA) [25] Compared to the coating agentsmentioned above TETA is currently used in the floatationprocess of sulfide minerals in Inco Limited as depressanttherefore it does not represent any extra cost On the otherhand TETA is a base which can neutralize protons producedin the oxidation of the sulphide minerals TETA has alreadybeen proved that it could retard the oxidation of pyrrhotiteand need not initial oxidation [25 26] However there is notdate on the capability of TETA to passivate pyrite In additionall the studies cited above were carried out by the method ofextraction using hydrogen peroxide or atmospheric oxygenas oxidant to test the coating effectiveness of different pas-sivating agents These processes usually require long timesand moreover the operation is complicated as the quantityof dissolved metal ions need to be monitored by techniquessuch as spectrophotometer [23]

As the simplicity efficacy and low cost of these methodselectrochemical techniques are used extensively to investigatethe corrosion of steel [27ndash30] Nowadays electrochemicaltechniques have been becoming essential measurements toevaluate the effect of inhibitors on the corrosion inhibition ofsteel Although pyrite is not a very good electrical conductorits oxidation is usually described in terms of electrochemicalcorrosion mechanisms developed for metals [31 32] There-fore electrochemical methods can be chosen to study thecorrosion inhibition behavior of passivating agents on pyrite

The main aim of this study is to test the coating effec-tiveness of triethylenetetramine (TETA) on pyrite using theopen-circuit potential (OCP) cyclic voltammetry (CV)potentiodynamic polarization and electrochemical imped-ance spectroscopy (EIS)

2 Experimental Methods

21 Mineral Samples Preparation Natural pyrite was obtain-ed from the Dabaoshan sulfur-polymetallic mines in thenorth of Guangdong Province China Its chemical composi-tion analysis by X-ray fluorescence (XRF) is listed in Table 1The XRD pattern (Figure 1) of the crushed sample is typicalthat was expected for pyrite and showed that it was includingtrace of quartzThematerial was groundwith an agatemortarand then sieved to isolate particles with a diameter of less than75 120583m and stored in a vacuum desiccator before usage

The pyrite sample was submitted to passivation by variousconcentrations of TETA solution 1 g of the pyrite powder wasprecisely weighed in a 50mL glass beaker and then 1mL ofcoating solutionwas added Sampleswere rinsedwell with thecoating solution and dried overnight in a vacuum desiccatorAll of these reagents in this experiment were analytical gradeMilli-Q water was used to prepare all the solutions After the

Table 1 Chemical composition of the studied pyrite sample

Compound MassFeS2 9333SiO2 338Al2O3 145MgO 028Cr2O3 001P2O5 004K2O 074TiO2 003MnO 003NiO 018CuO 018ZnO 020WO3 007PbO 005As2O3 004

coating step the particles were used to construct carbon pasteelectrodes

These electrodes were consisted of 10 g graphite 04mLparaffin oil and 05 g pristine or coated pyriteThemethod ofthe construction of C paste electrode was described by Arceand Gonzalez [33] A total of 10 g of graphite was pulverizedtogether with 05 g of pristine or coated pyrite in an agatemortar then 04 mL of silicon oil was added in the powderand mixed to obtain a homogeneous paste This paste wasplaced in a 7 cm long and 05 cm diameter glass tube Theelectrode surface was compacted on a plate glass to make itflat and its apparent active area was around 0196 cmminus2 Fromthe other end of the tube a copper wire with diameter of15mm was immersed in the paste as the conductor

Prior to the electrochemical study the surface of these Cpaste electrodes was sequentially polished with 300 600 and1200 grade silicon carbide paper And then these electrodeswere rinsed with distilled water and quickly transferred to thecell

22 Electrochemical Analysis The electrochemical measure-ments were performed in a typical electrochemical cell(200mL) with three electrodes the working electrode (Car-bon paste electrode with pristine or coated pyrite) thecounter electrode (a platinum foil electrode with 1 cm2 area)and the reference electrode (KCl-saturated calomel elec-trode) The electrolyte was 05mol Lminus1 H

2SO4solution

The electrochemicalmeasurementswere performedby anelectrochemical workstation (2273 Parstart) and the experi-mental data was recorded on a personal computer withsuitable software Cyclic voltammetry (CV) experimentswereconducted starting from open-circuit potentials (OCPs) ata sweep rate of 100mV sminus1 and the scan range was fromminus06VSCE to +08VSCE Polarization curves were mea-sured over the range of OCP plusmn200mV at a constant rate ofpotential change of 1mV sminus1 From these polarization curves

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 34: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Journal of Analytical Methods in Chemistry 3

20 25 30 35 40 45 50 55 60 65 700

500

1000

1500

2000

Inte

nsity

P

P

P P

P

P

P P PQ

Figure 1 XRD spectra of the pyrite P Pyrite Q quartz

corrosion current densities (119895corr) of different pyrite elec-trodes were obtainedThen the inhibition efficiency of TETAon pyrite can be calculated by using the following equation[27]

120578 () =119895corr minus 119895corr(inh)

119895corr (1a)

where 119895corr and 119895corr(inh) were the corrosion current densityof pristine and coated pyrite samples respectively

The impedance spectrawere obtained by applying a signalon theOCPwith a frequency range from 5times 105 to 1times 10minus2Hzwith a sinusoidal excitation signal of 10mV The impedancedata were analyzed using ZSimpWin softwareThe equivalentcircuit 119877

119904(1198761(11987711198762)) as shown in Figure 2 was used to fit

these impedance data As Bevilaqua et al [34] suggestedthis equivalent circuit was simplified from the circuit of119877119904(11987711198762(11987721198762)) and it described a response of the corrosion

process occurring at the open-circuit potential due to parallelanodic and cathodic reactions In the circuit of119877

119904(1198761(11987711198762))

119877119904represented the solution resistance 119877

1was the charge

transfer resistance in the initial stage of pyrite oxidation 1198761

was the constant phase element which was associated withthe capacitor of the double layer of the electrodeelectrolyteinterface with passive film and 119876

2represented the diffusion

impedance component a reaction limited by the diffusion ofoxygen According to the values of charge transfer resistancethe inhibition efficiency (IE) was obtained by using the fol-lowing equation [27]

IE =119877minus1

1

minus 1198771(inh)minus1

119877minus1

1

(1b)

where1198771and119877

1(inh)were the charge transfer resistance valuesof pristine and coated pyrite samples respectively

All of the above measurements were carried out in staticconditions All potentials quoted in this paper are referencedto the saturated calomel electrode (SCE)

Figure 2 Equivalent electrical circuits proposed for fitting imped-ance spectra of pyrite oxidation

3 Results and Discussion

31 Open-Circuit PotentialMeasurements Figure 3 shows theOCPs of the pyrite electrodes coated by different concentra-tions of TETA The OCP of the uncoated sample (denotedas control) was 3628mV and the OCPs of pyrite samplescoated by 1 TETA 2 TETA 3 TETA and 5 TETAwere3048mV 2792mV 2617mV and 1870mV respectively It isobvious that the OCPs of coated samples were lower thanthat of uncoated pyriteThis phenomenonwas ascribed to therelatively low redox potential of TETA [26]

32 Cyclic Voltammetry Measurements TheCV curves of thepristine and coated pyrite electrodes in 05mol Lminus1 H

2SO4

solution obtained by sweeping the potential from OCPtowards negative direction are shown in Figure 4 The shapeof the voltammetric curve was not significantly influencedby the presence of TETA indicating that the inhibitor doesnot change the mechanism of pyrite oxidation These curveswere similar to the other reported results [35 36] in whichthe reduction peaks between minus04V and minus02V can be inter-preted as two possible reactions (1) the reduction of S formedduring the handling and preparation of samples and (2) thereduction of FeS

2(s) to form FeS(s) and H

2S The reversal of

potential scan produces three anodic current peaks A1 A2

and A3 A1is attributed to the oxidation of the H

2S formed

electrochemically during the oxidation scan A2results from

the oxidation of pyrite via two steps [37 38]The first step is

FeS2rarr Fe2+ + 2S0 + 2eminus (2)

The second step is

Fe2+ + 3H2O rarr Fe(OH)

3+ 3H+ + eminus (3)

At high potentials the oxidation of sulfur to sulfate is expect-ed to occur [39] contributing to the appearance of the anodiccurrent peak A

3

Figure 5 shows the CV curves of the pristine and coatedpyrite electrode when the potentials were initially swept fromOCP towards the positive direction In addition to the anodicand cathodic current peaks mentioned above another catho-dic current peak between 03 V and 04V appeared when thepotential scan was reversed This peak was attributed to ironoxide reduction

The evidence of pyrite passivation by TETA can be madeby measuring its electrochemical activity [40] ComparingtheCV curves of the pyrite samples coated by various concen-trations of TETA all of the anodic and cathodic current peaks

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 35: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

4 Journal of Analytical Methods in Chemistry

0 100 200 300 400

018

02

022

024

026

028

03

032

034

036

5 TETA

3 TETA2 TETA

Pote

ntia

l (V

)

Times (s)

Control

1 TETA

Figure 3 Open-circuit potentials of the pyrite electrodes coated bydifferent concentration of TETA

minus08 minus06 minus04 minus02 0 02 04 06 08 1minus00025

minus0002

minus00015

minus0001

minus00005

0

00005

0001

00015

Curr

ent (

A)

Potential (V)

Control

1 TETA

2 TETA

3 TETA

5 TETA

minus1

Figure 4 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the negative direction

are decreased with an increase in TETA When 5 of TETAwas adopted in the coating treatment the anodic andcathodic current peaks almost could not be detected Thisproves that less-electrochemical activity takes place on thesurface of pyrite after being coated by TETAThe decrease ofelectrochemical activity should be attributed to the formationof a protective layer of TETA on the surface of pyrite samplesAs we know there are several amine molecules in the struc-ture of TETA consequently TETA can be absorbed on thepyrite surface through coordination bond formation betweenthe iron in pyrite and to the electron pair on the nitrogenatom [41]The inhibition efficiencies therefore depend on thecoverage area of the adsorbed molecule With an increaseof the concentration of TETA there is much larger surfacearea of pyrite coated by TETA so the inhibition efficiencyincreases

33 Potentiodynamic Polarization Test The Tafel polariza-tion curves for the pristine and coated pyrite electrodes in

minus08 minus06 minus04 minus02 0 02 04 06 08 1

minus0002

minus00015

minus0001

minus00005

0

00005

0001

Cur

rent

(A)

Potential (V)minus1

Control

1 TETA

2 TETA

3 TETA

5 TETA

Figure 5 Cyclic voltammograms of pyrite electrodes coated bydifferent concentration of TETA initiated in the positive direction

minus01 0 01 02 03 04 05 06

minus85

minus8minus75

minus7minus65

minus6minus55

minus5minus45

minus4minus35

Potential (V

(a)(b)(c)

(d)(e)

)

a controlb 1 TETAc 2 TETA

d 3 TETA e 5 TETA

Figure 6 Polarization curves of the pyrite electrodes coated bydifferent concentration of TETA

Table 2 Electrochemical polarization parameters and the corre-sponding inhibition efficiencies for pyrite coated with differentconcentrations of TETA

Concentrationof TETA ()

119864corr(mVSCE)

120573119888

(decade119881minus1)

120573119886

(decade119881minus1)

119895corr(mAcmminus2)

120578

()

0 253 959 744 00426 mdash1 226 882 673 00247 42082 206 791 596 00183 57043 187 772 523 00131 69245 100 770 453 00081 8098

05mol Lminus1 H2SO4solution are shown in Figure 6 It was

clear that the addition of TETA caused more negative shift incorrosion potential (119864corr) especially in high concentrations

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 36: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Journal of Analytical Methods in Chemistry 5

0 20 40 60 80 100 120 140 1600

20406080

100120140160180200

(a)

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

(b)

0 100 200 300 400 500 6000

100

200

300

400

500

600

(c)

0 100 200 300 400 500 600 7000

200

400

600

800

1000

(d)

0 200 400 600 800 10000

200

400

600

800

1000

1200

ExperimentalSimulated

(e)

Figure 7 Experimental and simulated Nyquist plots of pyrite samples coated by different concentrations of TETA (a) Uncoated (b) coatedby 1 TETA (c) coated by 2 TETA (d) coated by 3 TETA (e) coated by 5 TETA

It was consistent with the tendency of OPCs shown inFigure 3 It should be pointed out that the value of the cor-rosion potential of the same electrode in the same electrolytewas different from the value of the open-circuit potentialThis phenomenon was due to the concentrations of reductive

products at the interface of the electrode being higher thanin a real solution when the applied potential was swept fromnegative to positive potentials so the corrosion potentialobtained by the polarization curve is lower than the open-circuit potential [42]

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 37: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

6 Journal of Analytical Methods in Chemistry

Table 3 Parameters using the circuit 119877119904

(1198761

(1198771

1198762

)) and the corresponding inhibition efficiencies for pyrite coated with different concen-trations of TETA

Concentration of TETA () 119877119904

Ω cm2 11988401

10minus3

S s119899 cmminus2 n 1198771

Ω cm2 11988402

10minus3

S s119899 cmminus2 n 119909210minus4 IE ()

0 3363 421 08 4377 915 05 536 mdash1 3104 124 08 7691 570 05 214 43092 3001 121 08 9621 469 05 165 54503 3056 141 08 1543 389 06 402 71635 3264 134 08 2508 197 06 260 8255

From the Tafel polarization curves some electrochemicalcorrosion kinetic parameters can be obtained such as thecorrosion potential (119864corr) cathodic and anodic Tafel slopes(120573c120573a) and corrosion current density (119895corr) which are listedin Table 2

From the values of cathodic and anodic Tafel slopes bothcathodic and anodic processes were found that are inhibitedby the coating of TETA The cathodic Tafel slopes wereslightly decreased from 959 decV to 770 decV when theconcentration of TETA increasing from 0 to 5 Thisindicated that the cathodic reaction (the reduction of FeS

2)

is slightly inhibited by TETA When the pyrite samples werecoated by TETA the anodic slopes decreased remarkablywhich indicates that the inhibition of pyrite dissolution byTETA is mainly controlled by the anodic process ThereforeTETA can be classified as inhibitors of relatively mixed effect(anodiccathodic inhibition) in acid solution

The inhibition efficiencies (120578) have been calculated byusing (1a) which shows that the inhibition efficiencyincreases and the corrosion current density decreases withthe increase of the TETA concentration An increase from4208 to 8098 was found when the concentration ofTETA increased from 1 to 5 This could be explained thatthere is a larger surface area of pyrite sample coated by TETAwith the increase of TETA concentration

34 Electrochemical Impedance Spectroscopy Theexperimen-tal and simulated impedance diagrams for pyrite samplescoated by different concentrations of TETA are presented inFigure 7 Table 3 shows the quantitative results for impedancewhich fitted using the equivalent circuit 119877

119904(1198761(11987711198762)) as

mentioned above The fact of a low value of 1199092 which repre-sents the sum of quadratic deviations between experimentaland calculated data suggested that the proposed circuit is suit-able for explaining the EIS spectra Because all of the exper-iments were carried out in the same electrolyte the valuesof the solution resistance (119877

119904) were almost no change

The value of charge transfer resistance ldquo1198771rdquo is inversely

proportional to corrosion rate The charge transfer resistanceincreases with the increase in concentration of TETA 119877

1

increased from the value of 437Ω cm2 for the pristine pyriteto 2836Ω cm2 for the pyrite coated by highest concentrationof TETA which indicates that the corrosion of pyrite isobviously inhibited in the presence of TETA

According to (1b) the inhibition efficiencies (IE) havebeen calculatedThe obtained results show that the inhibition

efficiency increases while the charge transfer resistanceincreasedwhen the concentration of the TETA increasedTheresults obtained from the EIS method were in good agree-ment with those obtained from the polarization measure-ments

4 Conclusion

The feasibility of using TETA as a protecting agent to reducethe oxidation of pyrite had been studied using electrochemi-cal techniqueThe results show that TETA is an efficient coat-ing agent in preventing the oxidation of pyrite and the inhi-bition efficiency was more pronounced with TETA concen-tration The CV measurements reveal that TETA possessedstrong capability to be used as passivation agent for AMDcontrol The potentiodynamic polarization curves indicatethat TETA inhibited both anodic pyrite dissolution and alsocathodic hydrogen evolution reactions and it acted as mixedtype inhibitor in acid solution The values of inhibition effi-ciency obtained from the EIS method are in good agreementwith the results of polarization measurement

Acknowledgments

Thework is supported by the National Natural Science Foun-dation China (no 21207111) Research Foundation of Scienceand Technology Department of Hunan Province China(no 2012FJ4303) Research Foundation of Education BureauHunan Province China (no 12C0394) the Science Founda-tion ofXiangtanUniversity for the introduction of specializedpersonnel with doctorates (no 11QDZ17) and the OpenFoundation of Key Lab of Pollution Control and EcosystemRestoration in Industry Clusters Ministry of EducationChina

References

[1] A N Thorpe F E Senftle C C Alexander and F T DulongldquoOxidation of pyrite in coal to magnetiterdquo Fuel vol 63 no 5pp 662ndash668 1984

[2] M Perdicakis S Geoffroy N Grosselin and J Bessiere ldquoAppli-cation of the scanning reference electrode technique to evidencethe corrosion of a natural conductingmineral pyrite Inhibitingrole of thymolrdquo Electrochimica Acta vol 47 no 1 pp 211ndash2162001

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 38: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Journal of Analytical Methods in Chemistry 7

[3] R Garrels and M Thompson ldquoOxidation of pyrite by iron sul-fate solutionsrdquo American Journal of Science vol 258 pp 57ndash671960

[4] M P Silverman ldquoMechanism of bacterial pyrite oxidationrdquoJournal of Bacteriology vol 94 no 4 pp 1046ndash1051 1967

[5] J C Bennett and H Tributsch ldquoBacterial leaching patterns onpyrite crystal surfacesrdquo Journal of Bacteriology vol 134 no 1pp 310ndash317 1978

[6] R T Lowson ldquoAqueous oxidation of pyrite by molecular oxy-genrdquo Chemical Reviews vol 82 no 5 pp 461ndash497 1982

[7] C LWiersma and JD Rimstidt ldquoRates of reaction of pyrite andmarcasite with ferric iron at pH 2rdquoGeochimica et CosmochimicaActa vol 48 no 1 pp 85ndash92 1984

[8] V Nicholson R W Gillham and E J Reardon ldquoPyrite oxi-dation in carbonate-buffered solution 2 Rate control by oxidecoatingsrdquo Geochimica et Cosmochimica Acta vol 54 no 2 pp395ndash402 1990

[9] R Murphy and D R Strongin ldquoSurface reactivity of pyrite andrelated sulfidesrdquo Surface Science Reports vol 64 no 1 pp 1ndash452009

[10] T Xu S P White K Pruess and G H Brimhall ldquoModeling ofpyrite oxidation in saturated and unsaturated subsurface flowsystemsrdquo Transport in Porous Media vol 39 no 1 pp 25ndash562000

[11] P R Holmes and F K Crundwell ldquoThe kinetics of the oxidationof pyrite by ferric ions and dissolved oxygen an electrochemicalstudyrdquoGeochimica et CosmochimicaActa vol 64 no 2 pp 263ndash274 2000

[12] M Gleisner R B Herbert and P C Frogner Kockum ldquoPyriteoxidation by Acidithiobacillus ferrooxidans at various concen-trations of dissolved oxygenrdquo Chemical Geology vol 225 no1-2 pp 16ndash29 2006

[13] K J Edwards M O Schrenk R Hamers and J F BanfieldldquoMicrobial oxidation of pyrite experiments using microorgan-isms from an extreme acidic environmentrdquo American Mineral-ogist vol 83 no 11-12 pp 1444ndash1453 1998

[14] A A Sobek V Rastogi and D A Benedetti ldquoPrevention ofwater pollution problems in mining the bactericide technol-ogyrdquo International Journal ofMineWater vol 9 no 1ndash4 pp 133ndash148 1990

[15] I Doye and J Duchesne ldquoNeutralisation of acid mine drainagewith alkaline industrial residues laboratory investigation usingbatch-leaching testsrdquo Applied Geochemistry vol 18 no 8 pp1197ndash1213 2003

[16] M Benzaazoua P Marion I Picquet and B Bussiere ldquoThe useof pastefill as a solidification and stabilization process for thecontrol of acid mine drainagerdquoMinerals Engineering vol 17 no2 pp 233ndash243 2004

[17] C G Romano K U Mayer D R Jones D A Ellerbroek andD W Blowes ldquoEffectiveness of various cover scenarios on therate of sulfide oxidation of mine tailingsrdquo Journal of Hydrologyvol 271 no 1ndash4 pp 171ndash187 2003

[18] A Peppas K Komnitsas and I Halikia ldquoUse of organic coversfor acid mine drainage controlrdquo Minerals Engineering vol 13no 5 pp 563ndash574 2000

[19] G M Mudd S Chakrabarti and J Kodikara ldquoEvaluation ofengineering properties for the use of leached brown coal ash insoil coversrdquo Journal of Hazardous Materials vol 139 no 3 pp409ndash412 2007

[20] K Nyavor and N O Egiebor ldquoControl of pyrite oxidation byphosphate coatingrdquo Science of the Total Environment vol 162no 2-3 pp 225ndash237 1995

[21] Y L Zhang andV P Evangelou ldquoFormation of ferric hydroxide-silica coatings on pyrite and its oxidation behaviorrdquo Soil Sciencevol 163 no 1 pp 53ndash62 1998

[22] N Belzile S Maki Y W Chen and D Goldsack ldquoInhibitionof pyrite oxidation by surface treatmentrdquo Science of the TotalEnvironment vol 196 no 2 pp 177ndash186 1997

[23] A R Elsetinow M J Borda M A A Schoonen and DR Strongin ldquoSuppression of pyrite oxidation in acidic aque-ous environments using lipids having two hydrophobic tailsrdquoAdvances in Environmental Research vol 7 no 4 pp 969ndash9742003

[24] Y Lan X Huang and B Deng ldquoSuppression of pyrite oxidationby iron 8-hydroxyquinolinerdquo Archives of Environmental Con-tamination and Toxicology vol 43 no 2 pp 168ndash174 2002

[25] M F Cai Z Dang Y W Chen and N Belzile ldquoThe passivationof pyrrhotite by surface coatingrdquoChemosphere vol 61 no 5 pp659ndash667 2005

[26] YW Chen Y Li M F Cai N Belzile and Z Dang ldquoPreventingoxidation of iron sulfide minerals by polyethylene polyaminesrdquoMinerals Engineering vol 19 no 1 pp 19ndash27 2006

[27] Q B Zhang and Y X Hua ldquoCorrosion inhibition of mild steelby alkylimidazolium ionic liquids in hydrochloric acidrdquo Elec-trochimica Acta vol 54 no 6 pp 1881ndash1887 2009

[28] A Aytac U Ozmen and M Kabasakaloglu ldquoInvestigation ofsome Schiff bases as acidic corrosion of alloyAA3102rdquoMaterialsChemistry and Physics vol 89 no 1 pp 176ndash181 2005

[29] M Lebrini M Lagrenee H Vezin L Gengembre and FBentiss ldquoElectrochemical and quantum chemical studies ofnew thiadiazole derivatives adsorption on mild steel in normalhydrochloric acid mediumrdquo Corrosion Science vol 47 no 2 pp485ndash505 2005

[30] F Bentiss F Gassama D Barbry et al ldquoEnhanced corrosionresistance of mild steel in molar hydrochloric acid solu-tion by 14-bis(2-pyridyl)-5H-pyridazino[45-b]indole electro-chemical theoretical and XPS studiesrdquo Applied Surface Sciencevol 252 no 8 pp 2684ndash2691 2006

[31] B F Giannetti S H Bonilla C F Zinola and T RaboczkayldquoStudy of themain oxidation products of natural pyrite by volta-mmetric and photoelectrochemical responsesrdquo Hydrometal-lurgy vol 60 no 1 pp 41ndash53 2001

[32] D P Tao P E Richardson G H Luttrell and R H Yoon ldquoElec-trochemical studies of pyrite oxidation and reduction usingfreshly-fractured electrodes and rotating ring-disc electrodesrdquoElectrochimica Acta vol 48 no 24 pp 3615ndash3623 2003

[33] E M Arce and I Gonzalez ldquoA comparative study of electro-chemical behavior of chalcopyrite chalcocite and bornite in sul-furic acid solutionrdquo International Journal of Mineral Processingvol 67 no 1ndash4 pp 17ndash28 2002

[34] D Bevilaqua H A Acciari F A Arena et al ldquoUtilization ofelectrochemical impedance spectroscopy for monitoring bor-nite (Cu

5

FeS4

) oxidation by Acidithiobacillus ferrooxidansrdquoMinerals Engineering vol 22 no 3 pp 254ndash262 2009

[35] R Liu A LWolfe D A Dzombak C P Horwitz BW Stewartand R C Capo ldquoElectrochemical study of hydrothermal andsedimentary pyrite dissolutionrdquo Applied Geochemistry vol 23no 9 pp 2724ndash2734 2008

[36] H K Lin and W C Say ldquoStudy of pyrite oxidation by cyclicvoltammetric impedance spectroscopic and potential steptechniquesrdquo Journal of Applied Electrochemistry vol 29 no 8pp 987ndash994 1999

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 39: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

8 Journal of Analytical Methods in Chemistry

[37] C M V B Almeida and B F Giannetti ldquoComparative studyof electrochemical and thermal oxidation of pyriterdquo Journal ofSolid State Electrochemistry vol 6 no 2 pp 111ndash118 2002

[38] Y Liu Z Dang P Wu J Lu X Shu and L Zheng ldquoInfluenceof ferric iron on the electrochemical behavior of pyriterdquo Ionicsvol 17 no 2 pp 169ndash176 2011

[39] R Cruz V Bertrand M Monroy and I Gonzalez ldquoEffect ofsulfide impurities on the reactivity of pyrite and pyritic concen-trates a multi-tool approachrdquoApplied Geochemistry vol 16 no7-8 pp 803ndash819 2001

[40] P Acai E Sorrenti T Gorner M Polakovic M Kongolo andP de Donato ldquoPyrite passivation by humic acid investigated byinverse liquid chromatographyrdquoColloids and Surfaces A Physic-ochemical and Engineering Aspects vol 337 no 1ndash3 pp 39ndash462009

[41] S Sathiyanarayanan C Marikkannu and N PalaniswamyldquoCorrosion inhibition effect of tetramines for mild steel in 1MHClrdquo Applied Surface Science vol 241 no 3-4 pp 477ndash4842005

[42] S Y Shi Z H Fang and J R Ni ldquoElectrochemistry of mar-matitemdashcarbon paste electrode in the presence of bacterialstrainsrdquo Bioelectrochemistry vol 68 no 1 pp 113ndash118 2006

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 40: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2012 Article ID 713862 8 pagesdoi1011552012713862

Research Article

A Green Preconcentration Method for Determination ofCobalt and Lead in Fresh Surface and Waste Water Samples Priorto Flame Atomic Absorption Spectrometry

Naeemullah Tasneem Gul Kazi Faheem Shah Hassan Imran Afridi Sumaira KhanSadaf Sadia Arian and Kapil Dev Brahman

National Centre of Excellence in Analytical Chemistry University of Sindh Jamshoro 76080 Pakistan

Correspondence should be addressed to Naeemullah naeemullah433yahoocom

Received 4 July 2012 Accepted 5 October 2012

Academic Editor Jolanta Kumirska

Copyright copy 2012 Naeemullah et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead(Pb) in fresh and wastewater samples The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant Experiments were conducted to assessthe effect of different chemical variables such as pH amounts of reagents (oxine and Triton X-114) temperature incubation timeand sample volume After phase separation based on the cloud point the surfactant-rich phase was diluted with acidic ethanolprior to its analysis by the flame atomic absorption spectrometry (FAAS) The enhancement factors 70 and 50 with detectionlimits of 026 microg Lminus1 and 044 microg Lminus1 were obtained for Co and Pb respectively In order to validate the developed method acertified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with thecertified values The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and wastewater sample

1 Introduction

Release of large quantities of metals into the environment(especially in natural water) is responsible for a number ofenvironmental problems [1] Metals are major pollutants inmarine ground industrial and even treated waste waters[2] Industrial wastes are the major source of various kinds oftoxic metals which have nonbiodegradability and persistenceproperties resulted in a number of public health problems[3] Metals of interest cobalt (Co) and lead (Pb) were chosenbased on their industrial applications and potential pollutionimpact on the environment [4]

Pb is a toxic metal and widely distributed in theenvironment It is an accumulative toxic metal which isresponsible for a number of health problems [5]

Pb reaches humans from natural as well as anthropogenicsources for example drinking water soils industrial emis-sions car exhaust and contaminated food and beveragesTherefore highly sensitive and selective methods have

needed to be developed to determine the trace level of Pbin water samples The maximum contaminant levels of Pb indrinking water allowed by environmental protection agency(EPA) is 150 microg Lminus1 while the world health organization(WHO) for drinking water quality containing the guidelinevalue of 10 microg Lminus1 [6 7]

Co is known to be an essential micronutrient formetabolic processes in both plants and animals [8] It ismainly found in rocks soil water plants and animals Thedetermination of trace level of Co in natural waters is veryimportant because Co is important for living species and itis part of vitamin B12 [9] Exposures to a high level of Colead to serious public health problems and are responsiblefor several diseases in human such as in lung heart and skin[10]

Flame atomic absorption spectrometry (FAAS) is awidely used technique for quantification of metal speciesThe determination of metals in water samples is usuallyassociated with a step of preconcentration of the analyte

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 41: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

2 Journal of Analytical Methods in Chemistry

before detection [11] The determination of trace levels ofPb and Co in water samples is particularly difficult becauseof the usually low concentration on the bases of these facts agreat effort is needed to develop highly sensitive and selectivemethods to simultaneously determine trace level of thesemetals in water samples [12 13]

A variety of procedures for preconcentration of metalssuch as solid phase extraction (SPE) [14] liquid-liquidextraction (LLE) [15] and coprecipitation and cloud pointextraction (CPE) [16] have been developed Among themCPE is one of the most reliable and sophisticated separationmethods for the enrichment of trace metals from differenttypes of samples While other methods such as LLE areusually time consuming and labor intensive and requirerelatively large volumes of solvents which are not onlyresponsible for public health problems but also a majorcause of environmental pollution [17ndash22] It was reportedin literature that Pb and Co had been preconcentratedby CPE method after the formation of sparingly water-soluble complexes with different chelating agents such asammonium pyrrolidine dithiocarbamate (APDC) [23 24] 1-(2-thiazolylazo)-2-naphthol (TAN) [25] 1-(2-pyridylazo)-2-naphthol (PAN) [26 27] and diethyldithiocarbamate(DDTC) [28ndash30]

In the present work we introduce a simple sensitiveselective and low-cost procedure for simultaneous precon-centration of Co and Pb after the formation of complex withoxine using Triton X-114 as surfactant and later analysis byflame atomic absorption spectrometry Several experimentalvariables affecting the sensitivity and stability of separa-tionpreconcentration method were investigated in detailThe proposed method was applied for the determination oftrace amount of both metals in fresh surface and waste watersamples

2 Experimental

21 Chemical Reagents and Glassware Ultrapure waterobtained from ELGA lab water system (Bucks UK) was usedthroughout the work The nonionic surfactant Triton X-114was obtained from Sigma (St Louis MO USA) and was usedwithout further purification Stock standard solution of Pband Co at a concentration of 1000 microg Lminus1 was obtained fromthe Fluka Kamica (Bush Switzerland) Working standardsolutions were obtained by appropriate dilution of the stockstandard solutions before analysis Concentrated nitric acidand hydrochloric acid were analytical reagent grade fromMerck (Darmstadt Germany) and were checked for possibletrace Pb and Co contamination by preparing blanks for eachprocedure The 8-hydroxyquinoline (oxine) was obtainedfrom Merck prepared by dissolving appropriate amount ofreagent in 10 mL ethanol and diluting to 100 mL with 001 Macetic acid and were kept in a refrigerator 4C for one weekThe 01 M acetate and phosphate buffer were used to controlthe pH of the solutions The pH of the samples was adjustedto the desired pH by the addition of 01 mol Lminus1 HClNaOHsolution in the buffers For the accuracy of methodology acertified reference material of water SRM-1643e National

Institute of Standards and Technology (NIST GaithersburgMD USA) was used The glass and plastic wares were soakedin 10 nitric acid overnight and rinsed many times withdeionized water prior to use to avoid contamination

22 Instrumentation A centrifuge of WIROWKA Laborato-ryjna type WE-1 nr-6933 (speed range 0ndash6000 rpm timer 0ndash60 min 22050 Hz Mechanika Phecyzyjna Poland) was usedfor centrifugation The pH was measured by pH meter (720-pH meter Metrohm) Global positioning system (iFinderGPS Lowrance Mexico) was used for sampling locations

A Perkin Elmer Model 700 (Norwalk CT USA) atomicabsorption spectrometer equipped with hollow cathodelamps and an air-acetylene burner The instrumental param-eters were as follows wavelength 2407 and 2833 nm andslit widths 02 and 07 nm for Co and Pb Deuterium lampbackground correction was also used

23 Sample Collection and Preparation Procedure The freshsurface water samples (canals) and waste water were collectedon alternate month in 2011 from twenty (20) different sam-pling sites of Jamshoro Sindh (southern part of Pakistan)with the help of the global positioning system (GPS) Theunderstudy district positioned between 25 19ndash26 42 N and67 12ndash68 02 E The sampling network was designed tocover a wide range of the whole district The industrial wastewater samples of understudy areas were also collected Allwater samples were filtered through a 045 micropore sizemembrane filter to remove suspended particulate matter andwere stored at 4C

24 General Procedure for CPE For Co and Pb deter-mination aliquot of 25 mL of the standard or samplesolution containing both analytes (20ndash100 microgL) oxine 5 times10minus3 mol Lminus1 and Triton X-114 05 (vv) were added Toreach the cloud point temperature the system was allowedto stand for about 30 min into an ultrasonic bath at 50Cfor 10 min Separation of the two phases was achieved bycentrifuging for 10 min at 3500 rpm The contents of tubeswere cooled down in an ice bath for 10 min The supernatantwas then decanted by inverting the tube The surfactant-rich phase was treated with 200 microL of 01 mol Lminus1 HNO3

in ethanol (1 1 vv) in order to reduce its viscosity andfacilitate sample handling The final solution was introducedinto the flame by conventional aspiration Blank solution wassubmitted to the same procedure and measured in parallel tothe standards and real samples

3 Result and Discussion

31 Optimization of CPE The preconcentration of Pb andCo was based on the formation of a neutral hydrophobiccomplex with oxine which is subsequently trapped in themicellar phase of a nonionic surfactant (Triton X-114)Utilizing the thermally induced phase extraction separationprocess known as CPE the analyte is highly preconcentratedand free of interferences in a very small micellar phase Sev-eral parameters play a significant role in the performance of

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 42: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Journal of Analytical Methods in Chemistry 3

the surfactant system that is used and its ability to aggregatethus entrapping the analyte species The pH complexingreagent and surfactant concentration temperature and timewere studied for optimum analytical signals

32 Effect of pH The effect of pH on the CPE of Co and Pbwas investigated because this parameter plays an importantrole in metal-chelate formation The effect of pH upon theextraction of Co and Pb ions from the six replicate standardsolutions 200 microg Lminus1 was studied within the pH range of 3ndash10 while each operational desired pH value was obtained bythe addition of 01 mol Lminus1 of HNO3NaOH in the presenceof acetateborate buffer The maximum extraction efficiencyof understudy metals was obtained at pH range of 65ndash75 asshown in Figure 1 for subsequent work pH 70 was chosenas the optimum for subsequent work

33 Effect of Triton X-114 Concentration Separation of metalions by a cloud point method involves the prior formationof a complex with sufficient hydrophobicity to be extractedin a small volume of surfactant-rich phase The temper-ature corresponding to cloud point is correlated with thehydrophilic property of surfactants The nonionic surfactantTriton X-114 was chosen as surfactant due to its low cloudpoint temperature and high density of the surfactant-richphase which facilitates phase separation by centrifugationThe effect of Triton X-114 concentrations on the extractionefficiencies of Co and Pb were examined at the range of 01to 10 (vv) Figure 2 shows that quantitative extractionwas observed when surfactant concentration was gt 05(vv) At lower concentrations the extraction efficiency ofcomplexes was low probably because of the inadequacy of theassemblies to entrap the hydrophobic complex quantitativelyA Triton X-114 concentration of 05 (vv) was selected forsubsequent studies

34 Effect of Oxine Concentration The oxine is a relativelyvery stable and selective hydrophobic complexing reagentwhich reacts with both selected cations Replicate 10 mLof standard SRM and real sample solution in 05 (wv)Triton X-114 at a buffer of pH 70 and complexed with oxinesolutions in the range of 10ndash100times 10minus3 mol Lminus1 The resultsrevealed in Figure 3 that extraction efficiency of both metalsincreases up to 5 times 10minus3 mol Lminus1 This value was thereforeselected as the optimal chelating agent concentration Theconcentrations above this value have no significant effect onthe efficiency of CPE

35 Effects of Sample Volume on Preconcentration Factor Thepreconcentration factor (PCF) is defined as the concentra-tion ratio of the analyte in the final diluted surfactant-richextract ready for its determination and in the initial solutionAmong the other factors this depends on the phase rela-tionship on the distribution constant of the analyte betweenthe phases and on sample volume The sample volume isone of the most important parameters in the developmentof the preconcentration method since it determines thesensitivity and enhancement of the technique The phase

0

20

40

60

80

100

2 3 4 5 6 7 8 9 10

pH

PbCo

Rec

over

y (

)

Figure 1 Effect of pH on the percentage of recovery 20 microg Lminus1

of Pb and Co 50 times 10minus3 mol Lminus1 oxine 05 (vv) Triton X-114temperature 50C and centrifugation time 10 min (3500 rpm)

0

20

40

60

80

100

0 02 04 06 08 1

Triton X-114 (vv)

Rec

over

y (

)

PbCo

Figure 2 Effect of Triton X-114 on the percentage of recovery20 microg Lminus1 of Pb and Co 50 times 10minus3 mol Lminus1 oxine pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

0 2 4 6 8 1020

40

60

80

100

Rec

over

y (

)

Coxine (1times 10minus3 mol Lminus1)

PbCo

Figure 3 Effect of oxine concentration on the percentage ofrecovery 20 microg Lminus1 of Pb and Co 05 (vv) Triton X-114 pH 70temperature 50C and centrifugation time 10 min (3500 rpm)

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 43: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

4 Journal of Analytical Methods in Chemistry

Table 1 Influences of some foreign ions on the recoveries of cobalt and lead (20 microg Lminus1) determination by applied CPE method

Ion Concentration (microg Lminus1) Pb recovery () Co recovery ()

Na+ 20000 97plusmn 214 98plusmn 222

K+ 5000 98plusmn 221 99plusmn 302

Ca2+ 5000 98plusmn 212 97plusmn 112

Mg2+ 5000 97plusmn 104 98plusmn 308

Clminus 30000 99plusmn 205 98plusmn 304

Fminus 1000 96plusmn 301 97plusmn 112

NO3minus 3000 97plusmn 104 98plusmn 306

HCO3minus 1000 98plusmn 312 97plusmn 204

Al3+ 500 97plusmn 221 99plusmn 305

Fe3+ 50 96plusmn 223 97plusmn 302

Zn2+ 100 97plusmn 305 96plusmn 232

Cr3+ 100 96plusmn 208 98plusmn 225

Cd2+ 100 97plusmn 312 98plusmn 322

Ni2+ 100 96plusmn 223 97plusmn 301

Table 2 Analytical characteristics of the proposed method

Element condition Concentration range (microg Lminus1) Slope Intercept R2 RSD (n = 5)a LODb (microg Lminus1)

Co without preconcentration 250ndash5000 397times 10minus3 minus0013 09871 145 (500) 320

Co with preconcentration 200ndash100 0279 +0008 09997 222 (20) 026

Pb without preconcentration 250ndash5000 503times 10minus3 minus0034 09972 088 (600) 460

Pb with preconcentration 200ndash100 0256 minus0012 09989 188 (30) 044aValues in parentheses are the Co and Pb concentrations (microg Lminus1) for which the RSD was obtainedbLimit of detection calculated as three times the standard deviation of the blank signal

Table 3 Determination of cobalt and lead in certified reference material and water samples

(a)

Certified reference materialCertified values (microg Lminus1) Measured values (microg Lminus1) Percentage of recovery (RSD )

Co Pb Co Pb Co Pb

SRM 1643e 2706plusmn 03 1963plusmn 02 268plusmn 082 1924plusmn 05 990 (306) 980 (260)

(b)

SamplesAdded (microg Lminus1) Measured (microg Lminus1) Recovery ()

Co Pb Co Pb Co Pb

Canal water

0 0 334plusmn 0962 608plusmn 0781 mdash mdash

2 2 532plusmn 0384 806plusmn 0822 998 99

5 5 833plusmn 0432 110plusmn 0784 100 984

10 10 133plusmn 0642 159plusmn 0828 996 982

Mean plusmn SD (n = 3)

Table 4 Determination of lead and cobalt in water samples

Sample Co (microg Lminus1) Pb (microg Lminus1)

Canal water 334plusmn 0962 608plusmn 0781

Waste water 146plusmn 120 173plusmn 152

Mean plusmn SD (n = 3)

ratio is an important factor which has an effect on theextraction recovery of cations A low phases ratio improvesthe recovery of analytes but decreases the preconcentrationfactor However to determine the optimum amount of the

phase ratio different volumes of a water sample 10ndash1000 mLand a constant volume of surfactant solution 05 werechosen The obtained results show that with increasing thesample volume gt100 mL the extracted understudy analyteswere decreased as compared to those obtained with 25ndash50 mL A successful cloud point extraction should maximizethe extraction efficiency by minimizing the phase volumeratio thus improving its concentration factor In the presentwork the initial sample volume was 25 mL and the finalvolume of surfactant rich phase after diluted with acidicethanol was 05 mL hence the PCF achieved in this work was50 for both understudy analytes

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 44: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Journal of Analytical Methods in Chemistry 5

Table 5 Comparative table for determination of cobalt and lead in different types of samples applying CPE before analysis by atomicspectrometric technique

Reagent and surfactant Matrix and technique PFa and EFb LODc (microg Lminus1) Reference

Cobalt

TANTriton X-114 Water(FAAS) mdash57b 024 [25]

PANTX-100 Water samples(GFAAS) mdash100b 0003 [31]

PANTX-114 Urine(FAAS) mdash115b 038 [32]

5-Br-PADAPTX-100-SDS Pharmaceutical samples(FAAS) mdash29b 11 [14]

TANTriton X-100 Water(GFAAS) mdash100b 0003 [33]

APDCTriton X-114 Biological tissues(TS-FF-FAAS) mdash130b 21 [34]

APDCTriton X-114 Water(FAAS) mdash20b 50 [23]

12-NN PONPE 75 Water sample(FAAS) mdash27b 122 [35]

Me-BTABrTriton X-114 Water sample(FAAS) mdash28b 09 [36]

OxineTriton X-114 Water sample(FAAS) 5050 044 Present work

Lead

DDTPTriton X-114 Human hair(FAAS) mdash43b 286 [28]

PONPE 75mdash Human saliva(FAAS) mdash10b mdash [37]

APDCTriton X-114 Certified biological reference materials(ETAAS) mdash225b 004cmdash [24]

DDTPTriton X-114 Certified blood reference samples(ETAAS) mdash34b 008 [38]

PONPE 75mdash Tap water certified reference material(ICP-OES) mdashgt300b 007 [39]

DDTPTriton X-114 Riverine and sea water enriched water reference materials(ICP-MS) mdashmdash 400 [40]

5-Br-PADAPTriton X-114 Water(GFAAS) 50amdash 008cmdash [41]

PANTriton X-114 Water(FAAS) mdash556b 11 [27]

mdashTween 80 Environmental sampleFAAS 10amdash 72 [42]

TANTriton X-114 Water sample(FAAS) 151amdash 45 [43]

PyrogallolTriton X-114 Water sample(FAAS) 72amdash 04 [44]

OxineTriton X-114 Water sample(FAAS) 5070 026 Present workapreconcentration factor benhancement factor and climit of detection

36 Interferences The interference is those relating to thepreconcentration step which may react with oxine anddecrease the extraction To perform this study 25 mLsolution containing 20 microgLminus1 of both metals at differentinterference to analyte ratio were subjected to the developedprocedure Table 1 shows the tolerance limits of the interfer-ing ions error lt5 The tolerance limit of coexisting ionsis defined as the largest amount making variation of lessthan 5 in the recovery of analytes The effects of represen-tative potential interfering species were tested Commonlyencountered matrix components such as alkali and alkalineearth elements generally do not form stable complexes underthe experimental conditions A high concentration of oxinereagent was used for the complete chelation of the selectedions even in the presence of interferent ions

37 Analytical Figures of Merit The calibration graphusing the preconcentration step for Co and Pb werelinear with a concentration range of 50ndash20 ug Lminus1 ofstandards and subjecting to CPE methods at optimumlevels of all understudy variables The extracted analytesin diluted micellar media were introduced into the flameby conventional aspiration Table 2 gives the calibrationparameters for the proposed CPE method including thelinear ranges relative standard deviation RSD and limit

of detection LOD The experimental enhancement factorscalculated as the ratio of the slopes of calibration graphs withand without preconcentration The enhancement factors ofCo and Pb subjected to CPE method were found to be 70 and50 respectively The limits of detection LOD were calculatedas the ratio between three times the standard deviationof ten blank readings and the slope of the calibrationcurve after preconcentration were calculated as 026 and044 microg Lminus1 respectively for Co and Pb The obtained LODwas sufficiently low for detecting trace levels of Co and Pb indifferent types of fresh and waste water samples

The accuracy of the proposed method was evaluated byanalyzing a standard reference material of water SRM-1643ewith certified values of Co and Pb content It was found thatthere is no significant difference between results obtainedby the proposed method and the certified results of bothmetals Reliability of the proposed method was also checkedby spiking both metals at to three concentration levels (20ndash100 microg Lminus1) in a real water sample The results are presentedin Tables 3(a) and 3(b) The perecentage of recoveries (R) ofspike standards were calculated as follows

R () = (Cm minus Co)m

times 100 (1)

where Cm is a value of metal in a spiked sample Co the valueof metal in a sample and m is the amount of metal spiked

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 45: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

6 Journal of Analytical Methods in Chemistry

These results demonstrate the applicability of developedprocedure for Co and Pb determination in different watersamples

38 Application to Real Samples The CPE procedure wasapplied to determine Co and Pb in fresh surface and wastewater samples The results are shown in Table 4 The Co andPb concentrations in fresh surface water were found in therange of 212ndash512 microg Lminus1 and 149ndash856 microg Lminus1 respectivelyIn waste water the levels of both analyte were high found inthe range of 136ndash168 and 151ndash194 microg Lminus1 for Co and Pbrespectively

4 Conclusion

In this study Triton X-114 was chosen for the formation ofthe surfactant-rich phase due to its excellent physicochemicalcharacteristics low cloud point temperature high density ofthe surfactant-rich phase which facilitates phase separationeasily by centrifugation and commercial availability andrelatively low price and low toxicity This method is apromising alternative for the determination of Co andPb linked with FAAS From the results obtained it canbe considered that oxine is an efficient ligand for cloudpoint extraction of Co and Pb The simple accessibility theformation of stable complexes and consistency with thecloud point extraction method are the major advantagesof the use of oxine in cloud point extraction of Co andPb CPE has been shown to be a practicable and versatilemethod being adequate for environmental studies Cloudpoint extraction is an easy safe rapid inexpensive andenvironmentally friendly methodology for preconcentrationand separation of trace metals in aqueous solutions Thesurfactant-rich phase can be directly introduced into flameatomic absorption spectrometer FAAS after dilution withacidic ethanol The proposed CPE method incorporatingoxine as chelating agent permits effective separation andpreconcentration of Co and Pb and final determinationby FAAS provides a novel route for trace determinationof these metals in water samples of different ecosystemA low-cost surfactant was used thus toxic organic solventextraction generating waste disposal problems was avoidedThe comparison of the results found in the presented studyand some works in the literature was given in [31ndash44]The proposed cloud point extraction method is superiorfor having lower detection limits when compared to othermethods as shown in Table 5

Acknowledgment

The authors would like to thank the National center ofExcellence in Analytical Chemistry (NCEAC) Universityof Sindh Jamshoro for providing financial support andexcellent research lab facilities for scholars to carry out theresearch work

References

[1] M Soylak L Elci and M Dogan ldquoDetermination of sometrace metals in dial- ysis solutions by atomic absorptionspectrometry after preconcentrationrdquo Analytical Letters vol26 pp 1997ndash2007 1993

[2] Y Bayrak Y Yesiloglu and U Gecgel ldquoAdsorption behaviorof Cr(VI) on activated hazelnut shell ash and activatedbentoniterdquo Microporous and Mesoporous Materials vol 91 no1ndash3 pp 107ndash110 2006

[3] M Kobya E Demirbas E Senturk and M Ince ldquoAdsorptionof heavy metal ions from aqueous solutions by activatedcarbon prepared from apricot stonerdquo Bioresource Technologyvol 96 no 13 pp 1518ndash1521 2005

[4] M Kazemipour M Ansari S Tajrobehkar M Majdzadehand H R Kermani ldquoRemoval of lead cadmium zinc andcopper from industrial wastewater by carbon developed fromwalnut hazelnut almond pistachio shell and apricot stonerdquoJournal of Hazardous Materials vol 150 no 2 pp 322ndash3272008

[5] F Shah T G Kazi H I Afridi et al ldquoEnvironmentalexposure of lead and iron deficit anemia in children ageranged 1ndash5years a cross sectional studyrdquo Science of the TotalEnvironment vol 408 no 22 pp 5325ndash5330 2010

[6] D L Tsalev and Z K Zaprianov Atomic Absorption inOccupational and Environmental Health Practice AnalyticalAspects and Health Significance CRC Press Boca Raton FlaUSA 1983

[7] H G Seiler A Siegel and H Siegel Handbook on Metals inClinical and Analytical Chemistry Marcel Dekker New YorkNY USA 1994

[8] A Sasmaz and M Yaman ldquoDistribution of chromium nickeland cobalt in different parts of plant species and soil in miningarea of Keban Turkeyrdquo Communications in Soil Science andPlant Analysis vol 37 pp 1845ndash1857 2006

[9] M Soylak L Elci and M Dogan ldquoDetermination oftrace amounts of cobalt in natural water samples as 4-(2-Thiazolylazo) recorcinol complex after adsorptive preconcen-trationrdquo Analytical Letters vol 30 no 3 pp 623ndash631 1997

[10] M Soylak L Elci I Narin and M Dogan ldquoApplication ofsolid phase extraction for the preconcentration and separationof trace amounts of cobalt from urinrdquo Trace Elements andElectrolytes vol 18 pp 26ndash29 2001

[11] V A Lemos and G T David ldquoAn on-line cloud pointextraction system for flame atomic absorption spectrometricdetermination of trace manganese in food samplesrdquo Micro-chemical Journal vol 94 no 1 pp 42ndash47 2010

[12] M Ghaedi M R Fathi F Marahel and F Ahmadi ldquoSimulta-neous preconcentration and determination of copper nickelcobalt and lead ions content by flame atomic absorptionspectrometryrdquo Fresenius Environmental Bulletin vol 14 no12 B pp 1158ndash1163 2005

[13] M D G Pereira and M A Z Arruda ldquoTrends in precon-centration procedures for metal determination using atomicspectrometry techniquesrdquo Mikrochimica Acta vol 141 no 3-4 pp 115ndash131 2003

[14] C C Nascentes and M A Z Arruda ldquoCloud point formationbased on mixed micelles in the presence of electrolytes forcobalt extraction and preconcentrationrdquo Talanta vol 61 no6 pp 759ndash768 2003

[15] A Shokrollahi M Ghaedi S Gharaghani M R Fathi andM Soylak ldquoCloud point extraction for the determination ofcopper in environmental samples by flame atomic absorptionspectrometryrdquo Quimica Nova vol 31 no 1 pp 70ndash74 2008

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 46: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

Journal of Analytical Methods in Chemistry 7

[16] J A Baig T G Kazi A Q Shah et al ldquoOptimization ofcloud point extraction and solid phase extraction methodsfor speciation of arsenic in natural water using multivariatetechniquerdquo Analytica Chimica Acta vol 651 no 1 pp 57ndash632009

[17] P Liu Q Pu and Z Su ldquoSynthesis of silica gel immobilizedthiourea and its application to the on-line preconcentrationand separation of silver gold and palladiumrdquo Analyst vol 125no 1 pp 147ndash150 2000

[18] C D Stalikas ldquoMicelle-mediated extraction as a tool forseparation and preconcentration in metal analysisrdquo TrACTrends in Analytical Chemistry vol 21 no 5 pp 343ndash3552002

[19] Z Wang M Jing F S Lee and X Wang ldquoSynthesis of 8-hydroxyquinoline Bonded Silica (SHQ) and its application inflow injection-inductively coupled plasma mass spectrometryanalysis of trace metals in seawaterrdquo Chinese Journal ofAnalytical Chemistry vol 34 no 4 pp 459ndash462 2006

[20] X-J Sun B Welz and M Sperling ldquoDetermination of leadin wine by the FIAS-FAAS combination on-line preconcentra-tion systemrdquo Chemical Journal of Chinese Universities vol 17no 8 pp 1219ndash1221 1996

[21] M Soylak ldquoDetermination of trace amounts of copper inhigh-purity aluminum samples after preconcentration on anactivated carbon columnrdquo Fresenius Environmental Bulletinvol 7 no 7-8 pp 383ndash387 1998

[22] J L Manzoori and G Karim-Nezhad ldquoDevelopment of acloud point extraction and preconcentration method forCd and Ni prior to flame atomic absorption spectrometricdeterminationrdquo Analytica Chimica Acta vol 521 no 2 pp173ndash177 2004

[23] D L Giokas E K Paleologos S M Tzouwara-Karayanni andM I Karayannis ldquoSingle-sample cloud point determinationof iron cobalt and nickel by flow injection analysis flameatomic absorption spectrometrymdashapplication to real samplesand certified reference materialsrdquo Journal of Analytical AtomicSpectrometry vol 16 no 5 pp 521ndash526 2001

[24] J L Manzoori and A Bavili-Tabrizi ldquoThe application ofcloud point preconcentration for the determination of Cuin real samples by flame atomic absorption spectrometryrdquoMicrochemical Journal vol 72 no 1 pp 1ndash7 2002

[25] J Chen and K C Teo ldquoDetermination of cobalt and nickel inwater samples by flame atomic absorption spectrometry aftercloud point extractionrdquo Analytica Chimica Acta vol 434 no2 pp 325ndash330 2001

[26] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[27] J Chen and K C Teo ldquoDetermination of cadmium copperlead and zinc in water samples by flame atomic absorptionspectrometry after cloud point extractionrdquo Analytica ChimicaActa vol 450 no 1-2 pp 215ndash222 2001

[28] J L Manzoori and A Bavili-Tabrizi ldquoCloud point pre-concentration and flame atomic absorption spectrometricdetermination of Cd and Pb in human hairrdquo AnalyticaChimica Acta vol 470 no 2 pp 215ndash221 2002

[29] A Ohashi H Ito C Kanai H Imura and K OhashildquoCloud point extraction of iron(III) and vanadium(V) using8-quinolinol derivatives and Triton X-100 and determinationof 10-7 mol dm -3 level iron(III) in riverine water reference bya graphite furnace atomic absorption spectroscopyrdquo Talantavol 65 no 2 pp 525ndash530 2005

[30] D Zhao R Bian Y Ding and L Li ldquoDetermination of leadand cadmium in water samples by cloud point extraction priorto flame atomic absorption spectrometry determinationrdquoJournal of the Iranian Chemical Research vol 6 no 2 pp 87ndash94 2009

[31] Y Zhang W H Luo and H Li ldquoDetermination of trace cobaltin water samples by gra phite furnace a tomic absorptionspectrometry after cloud pointrdquo Spectroscopy Spectral Analysisvol 25 pp 576ndash578 2005

[32] J L Manzoori and G Karim-Nezhad ldquoSensitive and simplecloud-point preconcentration atomic absorption spectrom-etry application to the determination of cobalt in urinesamplesrdquo Analytical Sciences vol 19 no 4 pp 579ndash583 2003

[33] Ma C C Oliveros O J De Blas J L P Pavon and B MCordero ldquoCloud point preconcentration and flame atomicabsorption spectrometry application to the determination ofnickel and zincrdquo Journal of Analytical Atomic Spectrometry vol13 no 6 pp 547ndash550 1998

[34] G L Donati C C Nascentes A R A Nogueira M A ZArruda and J A Nobrega ldquoAcid extraction and cloud pointpreconcentration as sample preparation strategies for cobaltdetermination in biological materials by thermospray flamefurnace atomic absorption spectrometryrdquo Microchemical Jour-nal vol 82 no 2 pp 189ndash195 2006

[35] J L Manzoori and A Bavili-Tabrizi ldquoCloud point preconcen-tration and flame atomic absorption spectrometric determi-nation of cobalt and nickel in water samplesrdquo MikrochimicaActa vol 141 no 3-4 pp 201ndash207 2003

[36] V A Lemos R d Franca and B O Moreira ldquoCloud pointextraction for Co and Ni determination in water samplesby flame atomic absorption spectrometryrdquo Separation andPurification Technology vol 54 no 3 pp 349ndash354 2007

[37] M O Luconi M F Silva R A Olsina and L P FernandezldquoCloud point extraction of lead in saliva via use of nonionicPONPE 75 without added chelating agentsrdquo Talanta vol 51no 1 pp 123ndash129 2000

[38] F Shemirani M Baghdadi M Ramezani and M R JamalildquoDetermination of ultra trace amounts of bismuth in biolog-ical and water samples by electrothermal atomic absorptionspectrometry (ET-AAS) after cloud point extractionrdquo Analyt-ica Chimica Acta vol 534 no 1 pp 163ndash169 2005

[39] M O Luconi L L Sombra M F Silva L D Martinez RO Olsina and L P Fernandez ldquoDetermination of lead byflow injectionmdashinductively coupled plasmaoptical emissionspectrometry after cloud point enrichment without chelatingagentsrdquo Chemia Analityczna vol 48 p 749 2003

[40] M A M Da Silva V L A Frescura and A J Curtius ldquoDeter-mination of trace elements in water samples by ultrasonicnebulization inductively coupled plasma mass spectrometryafter cloud point extractionrdquo Spectrochimica acta Part B vol55 no 7 pp 803ndash813 2000

[41] J Chen S Xiao X Wu K Fang and W Liu ldquoDeterminationof lead in water samples by graphite furnace atomic absorptionspectrometry after cloud point extractionrdquo Talanta vol 67no 5 pp 992ndash996 2005

[42] S Candir I Narin and M Soylak ldquoLigandless cloud pointextraction of Cr(III) Pb(II) Cu(II) Ni(II) Bi(III) and Cd(II)ions in environmental samples with Tween 80 and flameatomic absorption spectrometric determinationrdquo Talanta vol77 no 1 pp 289ndash293 2008

[43] H Sang P Liang and D Du ldquoDetermination of tracealuminum in biological and water samples by cloud pointextraction preconcentration and graphite furnace atomic

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004

Page 47: Analysis and Fate of Emerging Pollutants during Water ...downloads.hindawi.com/journals/specialissues/213808.pdf · Guest Editors: Fei Qi, Guang-Guo Ying, Kaimin Shih, Jolanta Kumirska,

8 Journal of Analytical Methods in Chemistry

absorption spectrometry detectionrdquo Journal of HazardousMaterials vol 154 no 1ndash3 pp 1127ndash1132 2008

[44] F Shemirani S D Abkenar and A Khatouni ldquoDeterminationof trace amounts of lead and copper in water samples by flameatomic absorption spectrometry after cloud point extractionrdquoBulletin of the Korean Chemical Society vol 25 no 8 pp 1133ndash1136 2004