solid phase extraction of inorganic mercury using 5 ...€¦ · solid phase extraction of inorganic...

Hindawi Publishing CorporationThe Scientific World JournalVolume 2013 Article ID 134565 15 pageshttpdxdoiorg1011552013134565

Research ArticleSolid Phase Extraction of Inorganic Mercury Using5-Phenylazo-8-hydroxyquinoline and Determination byCold Vapor Atomic Fluorescence Spectroscopy inNatural Water Samples

Mirna Daye1 Baghdad Ouddane1 Jalal Halwani2 and Mariam Hamzeh1

1 Universite Lille 1 Equipe Chimie Analytique et Marine UMR-CNRS 8217 Geosystemes Villeneuve drsquoAscq Cedex France2Water amp Environmental Sciences Laboratory (LSEE) Lebanese University Lebanon

Correspondence should be addressed to Baghdad Ouddane baghdadouddaneuniv-lille1fr

Received 1 August 2013 Accepted 22 August 2013

Academic Editors S DrsquoIlio T Kaneta S Lee and R Zakrzewski

Copyright copy 2013 Mirna Daye 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

8-Hydroxyquinoline (8-HQ) was chosen as a powerful ligand for Hg solid phase extraction Among several chelating resins basedon 8-HQ 5-phenylazo-8-hydroxyquinoline (5Ph8HQ) is used for mercury extraction in which the adsorption dynamics were fullystudied It has been shown that Hg(II) is totally absorbed by 5Ph8HQwithin the first 30minutes of contact time with t

125minutes

following Langmuir adsorption model At pH 4 the affinity of mercury is unchallenged by other metals except for Cu(II) whichhave shown higher Kd value With these latter characteristics 5Ph8HQ was examined for the preconcentration of trace levels ofHg(II) The developed method showed quantitative recoveries of Hg(II) with LOD = 021 pgmLminus1 and RSD = 3ndash6 using coldvapor atomic fluorescence spectroscopy (CV-AFS) with a preconcentration factor greater than 250

1 Introduction

Mercury is a ubiquitous element and is one of the most toxicenvironmental pollutants In aquatic environments mercuryexists mainly as three forms which are elemental mercury(Hg∘) inorganicmercuryHg(II) and organicmercuryWhileall forms of mercury are poisonous methyl mercury isthe most toxic species due to its capacity of bioaccumula-tion through the aquatic food chain The most employedanalytical methods for trace mercury determination areinductively coupled plasma mass spectrometry (ICP-MS)Cold Vapor-Atomic Absorption Spectroscopy (CV-AAS)and cold vapor atomic fluorescence spectroscopy (CV-AFS)In natural waters mercury concentration is found at tracelevels in which most analytical techniques fail in its directdetermination Subsequently a separationpreconcentrationstep is often indispensable Among many preconcentrationmethods solid phase extraction (SPE) is the most used fortrace metal extraction

8-Hydroxyquinoline (8-HQ) has a complexing coordi-nating ability with over 60 metals with preference to transi-tion metals over alkali and alkaline earth metals It is evenused for the extraction of rare earth metals using a binarymixture of sec-octylphenoxyacetic acid-8-HQ [1] 8-HQforms chelates with metals of varying stability Log119870

1values

for Fe(III) Cu(II) Cd(II) Ca(II) and Mg(II) with 8-HQ are137 121 73 33 and 42 respectively [2] Stability constantof Ca(II) with immobilized 8-HQ was also determined by[3] with slightly higher value of log119870

1of 37 Moreover

Weaver and Harris [4] calculated the stability constant ofaluminum with alkyl-immobilized 8-HQ and found it to belog119870108 High stability constants were found for Cd(II)

with 8-HQ immobilized on controlled pore glass (CPG)ranging from 109ndash1011 [5] 8-HQ has been used extensivelyfor the preconcentration of tracemetals from natural samplesand seawater Silica has been used as a support in manyapplications for its numerous advantages as compared topolymers 8-HQ has been immobilized on various solid

2 The Scientific World Journal

matrices from XAD to activated carbon [6] Adsorptioncapacities have been determined for some metals that isCu(II) using 8-HQ functionalized CPG 58 120583moleg PorasilC porous silica 104 120583moleg and silica gel 216 120583moleg Itis evident that silica gel confers the largest capacity withan average molar coverage of 039 120583molem2 attributed toincreased surface area of 55384m2g (decreased pore size)[7]

Numerous synthesis routes have been described since thefirst immobilization of 8-hydroxyquinoline (8-HQ) on silicagel Diazo coupling of 8-HQ with p-aminobenzamide propylsilica was first reported in [23 34] The first techniques werefurther ameliorated by diazo coupling of 8-HQ on p-aminophenyl silica [24] or glass [25] Moreover the formation ofSchiff rsquos base on position 5 of 8-HQmoiety enables its fixationon p-aminopropyl silica bestowing extraordinary coordina-tion [26] Finally following the Mannich reaction whichoffers two possible procedures of 8-HQ immobilization onsilica phase one involving two steps reactions [27 28] andthe other one-step reaction [29 30] Among these synthesisroutes immobilization involving the diazo coupling of 8-HQ on p-aminobenzamide propyl silica was shown by manystudies to have an excellent retention of many trace metalsThe most powerful chelating 8-HQ-grafted silica is that withan exceptional coordination potential given by its anchoringposition on carbon 5 of 8-HQ moiety Therefore phenylazo-8-HQ was chosen in this study among other 8-HQ-5-graftedsilica due its higher yield product

Since then much research has been conducted tofully understand the complexing ability of phenylazo-8-HQ(5Ph8HQ) Spectroscopic studies of metal complexes with5Ph8HQ bound to silica showed 1 1 metal ligand stoichi-ometry in Cu2+ solution complex [31] Other studies havedetermined the protonation constants of 5Ph8HQ-graftedsilica to be 119901119870119886

1= 27 and 119901119870119886

2= 86 [31] However the

water soluble sulfo-derivative of 8-HQ 5-(p-sulfophenylazo)-8-hydroxyquinoline showed higher acid dissociation con-stants pKa

1of 378 and pKa

2of 794 [32] These values

would certainly change when the ligand is bound on silicaEquilibrium constants for 5Ph8HQ silica binding to metalshave been determined The stability constant of Cu2+ withthe grafted material was 119870∘ = 48 times 10

8 [31] showing higherstability constant with Sulfo-5Ph8HQ in water119870 = 14times10

10

[32] Recent study has showed higher equilibrium constantfor Cu2+ than the previously reported ones for 5Ph8HQ inmicelles and colloidal fumed silica-5Ph8HQ119870∘ = 127times10

11

and 119870∘

= 7 times 1011 respectively [33] Stability constant for

Ni2+ was also determined and found to beKrsquoext = 59 [24] andKrsquoext = 08ndash12 for 1 1 ligandmetal stoichiometry in presenceof either acetate or chloride counter ion [33] Stabilityconstants of metals with 8-HQ immobilized silica accordingto Luhrmann et al [28] protocol were also determinedwhich involved the functionalization of p-aminopropyl silicawith 5-chloro-methyl-8-hydroxyquinoline Using Luhrmannprotocol distribution ratios log119870

119863were determined for

many metals including Cu Ni Co Fe Mn Cr Zn CdHg and Pb using batch equilibrium technique for 8-HQ-grafted silica The use of the former protocol is not widely

studied because of its extremely high cost Many studieshave used 5Ph8HQ for the retention and preconcentrationof metals with excellent recoveries [5 34ndash38] Neverthelessthe adsorption dynamics of 5Ph8HQ-grafted silica is notcompletely studied particularly for mercury Thus in thisstudy we attempt to study the adsorption kinetics of mer-cury in single- and multielement solution to discover thecompetition demonstrated between mercury and differentmetals for 5Ph8HQ affinity sites Moreover in this studyadsorption isotherms of mercury and other metals weredetermined for 5Ph8HQ Finally an analytical method forthe determination of Hg(II) in river water was developedbased on 5Ph8HQ-linked silica as adsorbent and Cold VaporAtomic Fluorescence Spectroscopy (CV-AFS) as an analyticalinstrument

2 Materials and Methods

21 Chemicals and Materials

211 Reagents and Apparatus Analytical reagent-gradechemicals were used and obtained Sigma Aldrich (France)Ultrapure water (with a resistivity of 182 MΩ) was obtainedusing a Milli-Q system (Millipore USA) Silica (100ndash200mesh) chemicals and solvents were supplied fromSigma Aldrich (France) Labware was soaked in 20 nitricacid and washed thoroughly with pure water prior to useWorking solutions of metals ions (Cr(III) Cu(II) Co(II)Zn(II) Ni(II) Pb(II) Cd(II) As(II) Fe(III) V(II) andHg(II)) were prepared from stock metal nitrate solution(1000mgL) (Merck) Buffer solutions were prepared from1M sodium acetate to which different volumes of 1M nitricacid were added to obtain pH in the range 4ndash6 Ammoniumacetate and phosphate buffer were used for obtaining pH 7and pH 8 respectively

Fourier transform infrared (FT-IR) spectra of functional-ized silica were recorded using Nicolet 380 Smart iTR spec-trometer (ThermoScientific USA) and were silica-matrixcorrected An inductively coupled plasma mass spectrom-eter Thermo-Optek X7 (Thermo Fischer Scientific USA)equipped with a cross-flow pneumatic nebulizer a concentricglass-type nebulization chamber and a 15mm id quartzplasma torch was used All the operating parameters werethose recommended by the manufacturer The optimumoperating conditions and measurement parameters for ICP-MS are listed in Table 1 Measurements were performed withhigh-purity Argon gas The pH measurements and adjust-ments were conducted by pHmeter (Thermo ScientificOrionStar A111 USA) The flow rates of the samples were adjustedusing a Gilson Miniplus 3 peristaltic pump PVC tubes(318 id) were used for the preconcentration process Self-made PTFE (polytetrafluoroethylene) columns (65mm times

4mm id) were used for packing the examined adsorbentMercury was measured by cold vapor atomic fluorescencespectroscopy (Tekran Model 2600 CVAFSMercury AnalysisSystem USA) Ionic mercury is reduced with SnCl

2(2

solution in 1 HCl) subsequently converted from Hg(II)to Hg∘ The volatile species of mercury are separated from

The Scientific World Journal 3

Table 1 Operating conditions ICP-MS

Forward power (W) 1050Nebuliser gas flow (Lmin) 07Auxiliary gas flow (Lmin) 095Cool gas flow (Lmin) 135Quartz plasma torch ID (mm) 15Cone type PtGlass impact beadSpray chamber temperature (∘C) 3

Nebulizer type Glass concentricSample uptake rate (mLmin) 1Uptake delay (s) 35Washout delay (s) 75

Analytes51V 52Cr 55Mn 59Co

60Ni 65Cu 66Zn 111Cd208Pb 56Fe 75As

solution by purging with high-purity argon gas through asemipermeable dryer tube Volatile mercury is then carriedby argon gas and preconcentrated into a gold cell of thecold vapor atomic fluorescence spectrometer After thermaldesorption the concentration of Hg is determined by atomicfluorescence spectrometry at 2537 nm

22 Synthesis of 5Ph8HQ-Linked Silica Gel Phenylazo-8-hydroxyquinoline silica gel was prepared according to theprocedure proposed by Sugawara et al [34] The procedurefirstly consists in a coupling step between an arylamine moi-ety and aminopropyl silica gel (APSG) to permit further azo-linking of 8-hydroxyquinoline on position 5 APSG (10 g) wasalso acylated by treatment with p-nitrobenzoyl chloride (1 g)in chloroform (60mL) in presence of triethylamine (2mL)The nitro adduct was then reduced by sodium dithionite(5 wv solution) to yield aminobenzoyl-APSG Oxidationof the amino moiety with sodium nitrite afforded formationof the expected diazonium salt which was rapidly filtered tobe coupled with 8-HQ Formation of the final adduct wascharacterized by the rapid development of a deep red colorprominent feature of the formation of the expected diazo-linkage Presence of the anchored 8-hydroxyquinoline wasfurther ensured by FT-IR analysis which revealed absorptionbands from 1636 to 1524 cmminus1 relative to the presence ofamide and heteroaromatic bonds

23 Adsorption Experiments A series of metal sorptionexperiments were conducted to study the effect of pH sorp-tion kinetics selectivity adsorption capacities and interfer-ences of mercury and some other metals Batch experimentswere conducted using 1000mL polyethylene (PE) bottlesTheamount of adsorbent usedwas 1 g and the volume of ultrapurewater was maintained at 200mL A certain concentrationof metal ion was prepared by dilution of stock solution(1000mgL M+) and adjusted to the required pH using anadequate buffer system The bottles were shaken at roomtemperature for a fixed period of time at constant speed

150 rpm At the end of shaking time the supernatant wasseparated from the solid phase by filtration using Milliporefilters and analyzed by ICP-MS for metals and mercuryanalysis was performed using CV-AFS The experimentswere conducted in duplicates and the average results werereported This methodology was followed to identify the pHeffect optimize shaking time and understand the competi-tion between metals towards 5Ph8HQ sites and its effect onmercury adsorption efficiency

Metal uptake or sorption capacity was calculated basedon the difference of metal ion concentration before and afteradsorption according to (1)The percentage of mercury sorp-tion distribution coefficient selectivity coefficients and half-life sorption [39] were calculated using (1)ndash(5) respectivelyas follows

Sorption () =

119862119894minus 119862eq

119862119894

times 100 (1)

119876 =

(119862119894minus 119862eq)119881

119898 (2)

119870119889=

119876

119862eq (3)

120572 =119870119889(Hg (II))119870119889(119883)

(4)

11990512

=1

1198702119876eq

(5)

Here 119862119894(mgL) is the initial concentration 119862eq (mgL)

is the equilibrium concentration in the solution 119881 (L) is thesolution volume m (g) is the amount of sorbent 119876 (mgg)represents the sorption capacity and119876eq represents the sorp-tion capacity at equilibrium 119870

119889is distribution coefficient 120572

is the selectivity coefficient for the binding of a specific metalin the presence of other competitive ions 119883 represents themetal ion species

24 Kinetics Studies A certain concentration of metal ionsolution was prepared and adjusted to the optimized pHusing buffer system An accurately measured sorbent of 1 gwas added Different aliquots were sampled and filtered atdifferent time intervals for 24 hours Sorption dynamics werestudied inmercury singlemetal solution and binary solutionsof Hg(II)-Cu(II) Hg(II)-Co(II) Hg(II)-Ni(II) Hg(II)-V(II)and Hg(II)-Fe(III) Moreover adsorption kinetics were per-formed in multielement mixture composed of Hg(II) Cr(II)Fe(III) V(II) As(II) Co(II) Cu(II) Ni(II) Cd(II) Pb(II)and Mn(II)

Sorption kinetics were analyzed using pseudo-first-and second-order rate equations and intraparticle diffusionmodel Chemical reactions in homogenous systems aredescribed as pseudo-first-order rate equation The linearizedform of the first-order rate equation by Lagergren [40] isgiven as follows

Log (119876eq minus 119876119905) = log119876eq minus

1198701119905

2303 (6)


0

20

40

60

80

100

120

0 2 4 6 8 10

Reco

very

()

pH

VanadiumChromiumManganeseCobaltZinc

NickelCopperCadmiumLeadMercury

Figure 1 Effect of pH variation on the adsorption of metalsConditions volume 200mL m(5Ph8HQ) 1 g and [M+] 1 120583gmLminus1in single-metal solution Bars represent standard deviation for tworeplicates

where 119876eq and 119876119905are the amounts of metal ions adsorbed

at equilibrium (mmolg) and at contact t (min) respectivelyand119870

1(1min) is the rate constant

The linearized equation of pseudosecond order rateequation was given by Ho and McKay [41] as follows

1

119876119905

=1

11987021198762eq

+ (1

119876eq) 119905 (7)

where 1198702(gmmolsdotmin) is the rate constant of pseudo-

second-order adsorption reactionIntraparticular diffusion can be described to the model

given by [42] by the following

119876119905= 11987011989411990512

(8)

where 119870119894is the intraparticle diffusion rate constant (mmol

gsdotmin05)

25 Adsorption Isotherms Adsorption isotherms were deter-mined for Hg(II) Accurately measured 1 g of the sorbent wasmixed with 50mL of solution adjusted to the Hg optimalpH The concentration of metal ion was changed between10ndash160mgL while being shaked (agitation speed 150 rmin)The contact time was selected on the basis of the kineticsstudies At equilibrium time an aliquot was sampled filteredand analyzed The results were adjusted to the LangmuirFreundlich and Dubinin-Radushkevich (D-R) models [43ndash45] The Langmuir model linearized form is given by thefollowing

1

119876eq=

1

119876119898

+1

119887119876119898119862eq

(9)

where 119876eq (mmoleg) is the amount of metal ion adsorbed119862eq is the equilibrium metal ion concentration (mmolL)119876119898(mmoleg) is the maximum Langmuir uptake when the

surface of the adsorbent is completely coveredwith adsorbateand 119887 (Lmmole) is the Langmuir adsorption constant

The Freundlich linearized form is described by (10)

Log119876eq = log119870119865+

1

119899 log119862eq (10)

where 119876eq is the equilibrium metal ion concentration on theadsorbent (mmolg) 119862eq is the equilibrium concentrationof metal ion (mmoleL) 119870

119865is the Freundlich constant

(mmoleg) which indicates the adsorption capacity and thestrength of the adsorption and 119899 is the heterogeneity factorrepresenting bond distribution

The D-R adsorption isotherm linearized form is given bythe following

ln119876 = ln119876119898

minus 1198701205762 (11)

where 119876 is the amount of metal ion adsorbed per unitweight of the sorbent (moleg) 119870 is a constant related tothe adsorption energy (mol2KJminus2) 119876

119898is the maximum

adsorption capacity (moleg) and 120576 is the Polanyi potential(Jmole)

26 Preconcentration Study For optimization procedure thesynthesized 5Ph8HQ was cleaned by 20mL of 2M HNO

3

at flow rate 2mLmin washed by Milli-Q pure water untilfree from acid and finally conditioned by acetate-acetic acidbuffer system at flow rate 1mLmin Aliquots of 50mL ofriver water containing of 2 ngmLminus1 were adjusted to optimalextraction pH using ammonia or HNO

3Suprapur solution

Samples were percolated through 300mg precleaned resin atoptimized flow rate eluted with a suitable eluent and finallyanalyzed by CV-AFS

3 Results and Discussion

31 Effect of pH The effect of pH variation on metal uptakeof Hg(II) Cr(II) V(II) As(II) Co(II) Cu(II) Ni(II) Cd(II)Pb(II) Mn(II) and Zn(II) was investigated using batchprocedure in single-metal solution Solution acidity wasvaried between pH3 and 8At equilibrium time aliquotsweresampled filtered and analyzed Metal ion sorption can occurthrough several single or mixed mechanisms Coordinationwith the functional groups adhered to the sorbent throughchelation electrostatic attraction and anion exchange withprotonated amino group through proton or anion exchange

Figure 1 shows the effect of pH variation on metalretention on the grafted material The optimal adsorption ofmercury was found in the range 3-4 with pH 4 as the optimalacidity Above pH 4 Hg(II) retention decreases to 80 andfollows a steady trend between pH4 and 8 At pH greater than5 mercury forms colloidal precipitate of Hg(OH)

2or soluble

Hg(OH)+ The chemistry of mercury in aqueous solutionsis more complicated than any other metal Mercuric ionscan be easily hydrolyzed according to the equation [46]


The coordination of water influences mercury adsorptiondynamics and can relatively allow for slow diffusion

Hg(H2O)6

2+

997888rarr [Hg(H2O)5OH]+

+H+ (12)

The presence of Clminus can result in the formation ofHgCl+ HgCl

2and HgCl

4

2minus HgCl3

minus [47] and in the possibleelectrostatic adsorption on the resin depending on its chargedform The increase in retention might be attributed to thesespecies and not due to free Hg(II) Lower pH values areexpected to enhance protonated ligand sites available foradsorption Beyond pH 6 mercury uptake can decrease dueto precipitation for high concentration which is thereforenot applicable in our case The pH dependence of metaladsorption is the result of the effect of metal speciationand the ionization forms of different groups of the sorbentThe adsorption of mercury is possibly complexation andnot chemical binding since the zeta potential of 5Ph8HQis zero [33] The affinity of mercury toward the donor setatoms of 5Ph8HQ is due to hard and soft acid base theoryIt correlates the degree of metal softness to the observedstrength of interaction with the donor atoms (N O)Mercuryis considered as a soft metal because of its relatively largeionic size low electronegativity and high polarisability TheN=N ndashNH and OH of 5Ph8HQ are considered relativelysoft bases leading to the observed high affinities between eachother

The stability constant of Cu(II) with 8-HQ is elevated(log120573 = 1256) [48] which is demonstrated by high distri-bution coefficient value as discussed below Quantitativeadsorption of Cu(II) is found for pH values greater than 4 andthen slightly decreases due to the formation of strong com-plexes with carbonates Cu(CO

3)2

2minus (log120573 = 1069) [49] Theretention of Cd(II) is shown to be low for pH lt 6 in whichTurner et al [49] reported that 96 of Cd are found as ionicfree species for pH = 6 In seawater it has been reported thatwhen pH lt 6 Cd forms chlorocomplexes CdCl

2 CdCl

3

minusand CdCl

4

minus with high stability constants log120573 = 259 log120573 =

24 and log120573 = 147 [49] respectively which impedes itscomplexation with 8-HQ Thereby quantitative retention isachieved for pH values gt6 with the formation of weakhydroxide complexes Cd(OH)+ Cd(OH)

2 and Cd(OH)

3

minus oflog120573 = minus1008 log120573 = minus2035 and log120573 = minus333 [49]The stability constant of Cd with 8-HQ is high log120573 = 778which can easily break down the weak complexes formedwith hydroxides As for Mn(II) quantitative retention isattained for pH values gt6 At basic medium Mn forms weakcomplexes with hydroxides Mn(OH)+ (log120573 = minus1059) car-bonates Mn(CO

3) (log120573 = 41) [49] which seems far from

the competition with 8-HQ complexes (log120573 = 68)At acidic pH values the stability constant of Ni(II)

(log120573 = 927) andH+ (log120573 = 99) with 8-HQ is comparableTherefore quantitative recoveries of Ni(II) are found forpH ge 5 values although at pH 4 924 recovery of Ni(II)can be attained As shown in Figure 1 the retention of Pb(II)at low pH values is almost negligible This is due to thecompetition between Pb(II) andH+ to form stable complexeswith 8-HQ with log120573 = 91 and log120573 = 99 respectively Ashave been described for Ni(II) and Pb(II) Zn(II) follows the

same behavior with competition of H+ ions at low pH values(log120573 = 99) to form more stable complexes with 8-HQ thanZn-8-HQ complexes (log120573 = 856) Therefore quantitativeretention of Zn(II) is observed for pH ge 5

Quantitative recovery of Vanadium is only seen for 3 lt

PH lt 4 At higher pH values the retention decreases Thisis explained by the formation of V(IV) species at pH valueslt35 which are mainly VO2+ VO(OH)+ (VO(OH))

2

2+ andVO(OH)

2[50]At 35ltpHlt 75 anionic species formmainly

H2VO4

2minus and for 75 lt pH lt 13 the anionic form of HVO4

2minus

dominates [51] The retention of Cr(III) at the studied pHrange (3ndash8) is lower than 36 It is probably due to theformation of chromium under the oxidation state (V) whichforms CrO

4

2minus which certainly obstructs its complexationwith 8-HQ [52]

Arsenic showed no adsorption by 5ph8HQ at the studiedpH range (pH 3ndash8) In summary the adsorption of Pb(II)Cd(II) and Mn(II) was almost negligible between pH 3 and4 then it increased at pH gt 5 It is shown that basicconditions are favorable for Pb(II) retention At lower pHvalue the retention of these metals drops off probably dueto the partial protonation of active sites and the strongerelectrostatic repulsion between Pb(II) and the protonatedamino andhydroxyl groups of 5Ph8HQAt basicmedium theretention is higher which is appreciated in selective separa-tion fromHg(II) V(II) Cu(II) Ni(II) and Co(II) Moreoverat basic pH values functional groups of the sorbent arefree from protonation and therefore retention is controlledby chelation mechanism The corresponding affinity of theresin is attributed to the protonation of the free lone pairof nitrogen suitable for coordination with metals Values ofpH higher than 8 were not examined to prevent hydrolysis ofadsorbent and precipitation of metalsThe optimal pH valuesfor Hg(II) is 4 for V(II) is 4 for Cu(II) is 4 for Co(II) is 3-4 for Zn(II) and Ni(II) is 5ndash8 for Cd(II) and Pb(II) is 8 forCr(II) is 7 for Mn(II) is 7ndash8Therefore at pH 4 simultaneousextractions Hg(II) V(II) Cu(II) Co(II) and Ni(II) can beachieved by 5Ph8HQwithmaximal extractions occurring forHg(II) V(IV) Cu(II) and Co(II) with prominent separationfrom Pb(II) Cd(II) Mn(II) and Zn(II)

32 Adsorption Dynamics In order to determine the opti-mum contact time between 5Ph8HQ adsorption recoveries() were measured as a function of time in single-metalsolution and presented in Figure 2 Rapid uptake of metals bythe resin was observed within the first 10 minutes The timerequired to reach adsorption equilibrium was 30 minutes forV(IV) Cd(II) Cu(II) Zn(II) Hg(II) Ni(II) while slowerequilibrium time was attained for Mn(II) 1 hour and 5hours for Co(II) and Pb(II) Adsorption time equilibriumwascomparable to other resins and in some cases the adsorptionis faster than others reported in the literature [53 54] On theother hand in multielement mixture equilibrium time of Hgand other metals has shifted to longer time mainly becauseof interferences with other metals with stronger affinity to5Ph8HQ Mercury has reached equilibrium after 2 hourswhile for Co(II) Ni(II) Zn(II) and Fe(III) the adsorptiontime was longer and did not reach quantitative recoveries


020406080

100120

Reco

very

()

Mercury

5 10 15 20Contact time (min)

0times10

2

(a)

Vanadium


020406080

100120

0times10

2

(b)

Cobalt


020406080

100120

0times10

2

(c)

020406080

100120

Reco

very

()

Nickel


0times10

2

(d)

Lead


020406080

100120

0times10

2

(e)

Manganese


020406080

100120

0times10

2

(f)

020406080

100120

0 5 10 15 20

Reco

very

()

Contact time (min)

Cadmium

times102

(g)


Copper

020406080

100120

0times10

2

(h)

0 5 10 15 20Contact time (min)

Zinc

020406080

100120

times102

(i)

Figure 2 Recovery percentage ofmetals as function of time in a single-metal solution Conditions volume 200mLm(5Ph8HQ) 1 g elementoptimized pH and [M+] 1120583g mLminus1

after 24 hour contact time Still the equilibrium time ofCu(II) and V(IV) has not been influenced in multielementmixture revealing the significant affinity of these metalstowards the studied resin

In a single metal solution the lowest half-life sorptionswere that of Cu(II) 006min lt V(IV) 028min lt Ni(II)039min lt Zn(II) 041min lt Cd(II) 089min respectivelywhile slower sorption kinetics were found forHg(II) 539minlt Pb 2523min lt Co(II) 4996min (Table 2) Overall thefast adsorption of metals on 5Ph8HQ can be attributed tothe good hydrophilicity of silica and the chelating strengthof 5Ph8HQ towards metals In order to interpret the sorp-tion kinetics Lagergren first-order equation pseudo-secondorder equation andWebber-Morris intraparticular diffusionmodels were used to evaluate the experimental data

Table 2 shows adsorption kinetic parameters of differentmetals in single-metal solution First-order rate 119870

1was

determined from the slope and intercept of the plot of

log(119876eq minus 119876119905) versus 119905 The correlation coefficients (1198772)

were between 099ndash079 for all studied metals and 09641for Hg(II) As for pseudo second-order model correlationcoefficients were superior to 0999 for all systems The inap-plicability of the first kinetic model suggests the prevalenceof pseudo-second-order kinetic model on the adsorptionof metals on the studied sorbent in which the calculatedequilibrium adsorption capacities 119876

119890(theoretical) were in

accordance with the experimental adsorption capacities 119876119890

(experimental) Thereby chemisorption may control theadsorption mechanism involving valence forces throughsharing or exchange of electrons between the resin andmetals [55] Moreover the kinetic results were also fitted tointraparticular diffusion model by tracing 119902

119905versus 119905

12 Ifthe plots were straight lines passing through the origin thenthe adsorption mechanism is governed by intraparticulardiffusion defining the sole rate limiting step If plot 119902

119905versus

11990512 did not pass the origin then the adsorption might be


00 100 200 300 400 500

Time (min)

minus2

minus4

minus6

R2= 09641

log(QeminusQt)

(a)

0400000800000

12000001600000

0 500 1000 1500 2000Time (min)

R2= 1

tQt

(min

gm

moL

minus1)

(b)

000093000095000097000099000101

0 10 20 30 40

t12 (min)

R2= 07665

Qt

(mm

oLg

minus1)

(c)

020406080

100120

0 200 400 600 800

R2= 09604

1Qe

(gm

moL

minus1)

1Ce (LmmoLeminus1)(d)

00minus1minus2minus3minus4minus5

log Qe

minus05

minus1

minus15

minus2

minus25

R2= 09064

log Ce

(e)

0 2000000001205762

R2= 09446

minus124

minus12

minus116

minus112

minus108

minus104

lnQe

(f)

Figure 3 Adsorption kinetics of Hg(II) according to (a) pseudo-first-order model (b) pseudo-second-order model (c) intraparticulardiffusion [Hg2+] 0005mmol Lminus1 volume 200mL pH 4 and m(5Ph8HQ) 1 g Adsorption isotherms of Hg(II) by 5Ph8HQ accordingto (d) Langmuir adsorption model (e) Freundlich adsorption model and (f) Dubinin-Radushkevich adsorption model [Hg2+] 10ndash160 120583gmLminus1 volume 50mL pH 4 and m(5Ph8HQ) 1 g

Table 2 Adsorption kinetics of metals in single-metal solution

Metal First-order rate constants Second-order rate constant Intraparticular diffusion119876119890 (exp)

(mmol gminus1)119876119890 (theor)(mmol gminus1) 119870

1(minminus1) 119877

2 119876119890

(mmol gminus1)1198702

(gmmolminus1 minminus1) 1198772

11990512

119870119894

1198772

Co 0003394 00020068 000576 09988 000326 6140 09997 499 000005 07041V 0003926 00000176 000461 07997 000392 913816 1 03 00000006 05295Pb 0000965 00003075 000530 09559 000091 43728 09999 252 0000009 06236Cd 0001779 00000601 001313 09368 000178 627455 1 090 0000001 05016Cu 0003152 00000044 000668 09478 000311 5116770 1 006 00000001 05123Zn 0003059 00000122 000299 09195 000303 819968 1 040 00000004 08384Mn 0003640 00010354 001958 09961 000365 83622 1 327 000005 03805Ni 0003408 00000186 000484 09743 000340 739984 1 040 00000005 07674Hg 0000997 00000789 000507 09641 000100 186063 1 539 0000002 07665

dominated by film diffusion or boundary layer diffusion[56] As shown in Figure 3 the corresponding plot was notlinear over the studied time range Hg adsorption had aninitial linear portion followed by a plateau suggesting thegovernance of intraparticular diffusion in the few hoursof adsorption then film diffusion dominated These twodifferent stages of adsorption for Hg(II) are also seen forCo(II) V(IV) Cd(II) Cu(II) Zn(II) Ni(II) and Pb(II) withgood correlation coefficients attained for Zn of 08 and CoNi and Hg of 076 In contrast to other metals Mn(II)demonstrated only filmdiffusionwhere a plateau is only seen

In order to examine the influence ofmetals on the adsorp-tion kinetics of mercury adsorption kinetics were examinedin multielement mixture For this purpose a certain metal

ion concentration containing V(IV) Cr(II) Co(II) Ni(II)Cu(II) Zn(II) Fe(III) and Hg(II) was added to 1 g of5Ph8HQ at optimal pH for mercury sorption (pH 4) Metalmixture was shaken at 150 rpm and samples were taken atpredetermined time as described above As demonstratedin Table 3 the experimental data fitted-pseudo-second-ordermodel with correlation coefficient between 09 and 1 Thecalculated equilibrium adsorption capacities for almost allmetals tested were consistent with experimental data exceptfor Co(II) Ni(II) and Zn(II) It seems that the adsorptionof Ni Co and Zn is significantly affected in multielementmixture at pH 4 Similar to single-metal solution filmdiffusion predominated the trend of adsorption of metalsin multielement mixture except for Co which followedintraparticular diffusion model with correlation coefficients


of 097 Higher half-life sorption was found for all metalsin multielement mixture in which 119905

12 of some metals wastremendously affected The 11990512 of Ni(II) and Zn(II) were 230and 61 higher inmagnitude respectively than in single-metalsolutionThe sorption sequence of metals has been altered inmulti-element solution with fast adsorption for Cu V andHg The 119905

12 sorption sequence became as follows Cu(II)07min lt V(IV) 186min ltHg(II) 1452min lt Zn(II) 25minlt Ni(II) 8983min lt Fe(III) 124min lt Co(II) 11961min(Table 3) Therefore in multi-element solution Cu(II) andV(IV) appear to compete with Hg(II) for the adsorption sitesof 5Ph8HQ since these metals have faster sorption times

33 Competitive Adsorption

331 Multi-Element Mixture The selectivity is determinedby equilibrating a unit mass of the adsorbent in solutioncontaining the same initial concentration for all metalsSolution acidity was adjusted to 4 which is the optimal pHfor mercury adsorption The overall adsorption efficienciesof Cu(II) V(IV) and Hg(II) remained unaffected in multi-component mixture Maximum metal retention of 999998 993 942 81 79 325 14 and 10 wereobtained for Cu(II) Hg(II) V(IV) Fe(III) Co(II) Ni(II)Zn(II) Pb(II) andCd(II) respectively As a result the affinityorder can be as follows Cu(II) gt Hg(II) gt V(II) gt Fe(III)gt Ni(II) gt Co(II) gt Zn(II) gt Pb(II) gt Cd(II) The highestaffinities (119870

119889) were obtained for Cu(II) 15364 Hg(II) 50

and V(IV) 25 (Table 4) According to separation factor (120572)mercury can be separated from metals of high affinity to5Ph8HQ that is V(IV) Fe(III) Co(II) and Ni(II) howeverCu(II) poses a potential concurrence with Hg(II) towards theresin binding sites This is ascribed to the higher distributioncoefficient 119870

119889Cu(II) 14548 gt 119870

119889Hg(II) 50 and 120572 lt 1

332 Binary and SingleMetal-Solution Following the resultsof multi-element mixture the highest affinities of metalstowards 5Ph8HQ are obtained with an order Cu(II) gtHg(II)gtV(IV) gt Fe(III) gtNi(II) gtCo(II)Therefore it is interestingto identify the effects of these metal ions with mercury inbinary metal mixture at pH 4 The outlined order of metalion selectivity by 5Ph8HQ based on the values of distributioncoefficient and separation factor 120572 is Cu(II) gt Hg(II) gt

Co(II) gt V(IV) gt Ni(II) gt Fe(III) (Table 5) It seems thatthe affinity order as seen in Table 4 has changed in binarymetal mixture as compared to multi-element mixture withincreased values of 119870

119889and a decrease in the separation

factor 120572kHgkMm+ Change in the affinity of metals towardsdifferent sorbents with varying the competition potentialwas also observed in previous adsorption studies [57 58]According to the Irving-Williams series the stability of metalcomplexes with ligands is in the order Mn(II) lt Fe(II) lt

Co(II) lt Ni(II) lt Cu(II) gt Zn(II) [59] The crystal fieldtheory suggests electrostatic interaction between the centralatom and the ligand Therefore there is a direct relationshipbetween stability of metal complexes and ionic potential thatis the charge to radius ratio (Zr) Following the Zr ratiocited in Table 6 of the studied metals the selectivity sequence

0

0005

001

0015

002

0025

0 50 100 150

Concentration Hg(II) (mgLminus1)

Qe

(mm

oLg

minus1)

Figure 4 Adsorption profile of Hg(II) as a function of increasingmetal concentration Conditions [Hg2+] 10ndash160 120583gmLminus1 volume50mL pH 4 and m(5Ph8HQ) 1 g

is expected to be Mn(II) gt Ni(II) gt Co(II) = Zn(II) gt V(II)gt Cd(II) gt Hg(II) and for trivalent metals As(III) gt Cr(III)gt Fe(III) The stability sequence of metals is not consistentwith our results in either of the two mixed metal studies Theadsorption selectivity can shift from the predicted affinitiesdepending on the experimental conditions (pH etc) andsorbent properties A direct correlation is made between Zrratio ofmetals and themetal complex stability in pure cation-exchange mechanism [60] that could be not ascribed to thestudied resin Therefore it is also important to define theselectivity and the stability constants in single-metal solutionwithout the presence of competitor elements

Distribution coefficients are determined in single-metalsolution at element-optimized pH As demonstrated byTable 7 119870

119889has tremendously been altered to high values as

opposed to that observed in multi-element mixture still 119870119889

values for Cu(IV) V(II) and Hg(II) remained unchangedTherefore according to 119870

119889values metal affinity order

towards 5Ph8HQ can be as follows Mn(II) 9998gt Co(II)7998 gt Cd(II) 1998 gt Cu(II) 160 gt V(IV) 13773 gtNi(II) 595gtHg(II) 5237 gt Zn(II) 1884 gt Pb(II) 24

34 Adsorption Isotherms Adsorption isotherm studies areof great value for their importance in describing the inter-action between the solute adsorbent and the adsorbateThereby the effect of initial concentration of metal sorptionwas investigated by varying the initial concentrations ofmetalions at optimum pH The obtained results were presentedin Figure 3 As indicated in Figure 4 as the concentration ofmetal ion increases the larger is the equilibrium adsorptionuptake by the adsorbent There seems to be a direct relationbetween the loading capacity of the sorbent and themetal ionconcentration It can be explained by the fact that with higherconcentration the transfer driving force is larger [61] Theadsorption data formetals were analyzed and fitted accordingto Langmuir Freundlich and Dubinin-Radushkevich (D-R)models The Langmuir isotherm model suggests monolayersorption at specific homogenous site without interaction


Table 3 Adsorption kinetics of metals in multielement mixture at pH = 4

Metal First-order rate constants Second-order rate constant Intraparticular diffusion119876119890 (theor)(mmol gminus1) 119870

1(minminus1) 119877

2 119876119890

(mmolgminus1)1198702


11990512

119870119894

1198772

Co 000146 000230 09533 000255 3283 0991 11961 000004 09427V 000007 000299 08843 000390 137896 1 186 0000003 04423Cu 000004 000484 08318 000315 420290 1 076 0000001 06093Zn 000033 000553 09541 000096 41447 09998 2504 0000009 06659Ni 000161 000345 09552 000267 4169 09987 8983 000004 07309Fe 000193 000161 07571 000350 2302 09993 12409 0000008 03698Hg 000024 000668 07452 000100 68596 09998 1452 0000009 04446

Table 4 Metal distribution coefficient (119870119889) and separation factor (120572) at pH 4 in multielement mixture

Element V Co Ni Cu Zn Cd Pb Fe Hg119870119889

2512 048 058 15365 005 002 003 326 4976120572 119870119889Hg119870

119889M+ 198 10287 8599 032 93116 263832 146879 1528 mdash

between the sorbed molecules with sites having identi-cal adsorption energies The Freundlich isotherm sorptionassumes a monolayer sorption on heterogeneous sites withinteraction between the adsorbent and that the adsorbateand all adsorption sites are energetically different The D-Risotherm is consideredmore general than Langmuirmodel itdoes not assume homogenous surface or constant adsorptionpotential It is used to identify whether the adsorption is of achemical nature or a physical one [44]

The model constants of Langmuir Freundlich and D-R isotherms along with correlation coefficients values arelisted in Table 8 The 119877

2 values indicate that Langmuir fit theexperimental data better than Freundlich and D-R isothermmodels suggesting a monolayer coverage of Hg(II) on5Ph8HQ resin Langmuir isotherm adsorption type was alsofound forHg(II) with other studied resins thiourea-modifiedchitosan [62] and poly-allyl thiourea [13] The maximumadsorption capacity of Hg(II) on 5ph8HQ was found to be0022mmole Hg(II)g corresponding to a maximum Hg(II)initial concentration of 90mgL (Figure 4) The determinedadsorption capacity is considered as minimal as compared toother resins such as thiol-functionalized mesoporous silicamagnetite nanoparticles with 08mmole Hg(II)g [63] and039mmole Hg(II)g of silica supported dithiocarbamate[64] 113 mmole Hg(II)g of poly-allyl thiourea [13] 8-Hydroxyquinoline silica synthesized according to Luhrmannet al [28] showed higher capacity for Hg(II) 0448mmolegat optimized pH 6 The adsorption capacity for some metalshas also been reported usingHQ-silica synthesized accordingto different protocols Marshall and Mottola [7] found anadsorption capacity for Cu(II) 0227mmoleg while HQ-silica synthesized according to Pyell and Stork [27] showedhigher capacity of 0414mmoleg and 0248mmoleg forNi(II) and 0333mmoleg for Zn(II)

For Langmuirmodel to determine if the resin is favorablefor Hg(II) sorption a dimensionless separation factor isdefined as

119877119871=

1

1 + 119870119871119862119894

(13)

where 119870119871(Lmmole) is the Langmuir equilibrium constant

and 119862119900(mmoleL) is the initial concentration of metal ion If

119877119871gt 1 the isotherm is unfavorable if 119877

119871= 1 the isotherm is

linear if 0 lt 119877119871lt 1 the isotherm is favorable if 119877

119871= 0 the

isotherm is irreversible [65]The value of 119877119871in this study was

found to be 001 confirming the suitability of the resins forthe recovery of Hg(II) ions Moreover the low 119877

119871value lt 01

implies strong interaction between Hg(II) and 5Ph8HQ

35 5Ph8HQ Column Extraction of Hg(II)

351 Flow Rate Optimization The flow rate of Hg(II) solu-tion through the column is an important parameter in orderto ensure sufficient contact time between the sorbent andthe adsorbate and to control time of analysis The flow rateof samples was investigated in the range between 1 and5mLmin As shown in Figure 5 quantitative recoveries wereobtained for flow rates between 2 and 3mLmin At flowrate gt 3 mLmin recoveries drop off to 93 Therefore aflow rate of 2mLmin was used for the subsequent Hg(II)preconcentration

352 Eluent Type and Volume Optimization Elution ofHg(II) from 5Ph8HQ column was investigated by usingdifferent types of eluents following the general procedureThe results demonstrated in Figure 6 showed that even witha mixture of HCl + HNO

3 Hg(II) ions have not been

completely desorbed However the use HCl + HNO3as an

eluent for metals from 5Ph8HQ was proven to be efficient[36 37 66] This further accentuates the strong affinity ofHg(II) ions towards binding donor atoms (N O) of 5Ph8HQIn this case as other studies have reported for the desorptionofHg(II) [13 20] a strong complexing agent formercury suchas thiourea is added to varying concentrations of HCl Theobtained results show that 1MHCl mixed with [CS(NH

2)2]

ge2 was shown to be sufficient for quantitative desorption ofHg(II) ions (Figure 6) Even though 1MHCl + 2 CS(NH

2)2

was enough for the elution of Hg(II) ions a larger elutionvolume of 10mL was required for stripping off all the target


Table 5 Selectivity of mercury at pH 4 in binary mixtures

V Cu Ni Co Fe Hg119870119889

27011 159800 12829 35836 5260 52376120572 119870119889Hg119870

119889M+ 1939 03278 40825 1462 9957 mdash

Table 6 Metal ion charge to radius ratio [8]

Ion Oxidation state Coordination number 119885119877

Pb 2 6 168Zn 2 6 27Cd 2 6 211Cu 2 6 274Ni 2 6 29Cr 3 6 488Co 2 6 27V 2 6 253Fe 3 6 4651Hg 2 6 196As 3 6 5117Mn 2 6 298

0

20

40

60

80

100

120

0 2 4 6

Reco

very

()

Flow rate (mLminminus1)

Figure 5 Effect of flow ratemercury by 5Ph8HQcolumn extractionConditions [Hg2+] 2 ng mLminus1 119881 (50mL) pH 4 and eluent 5MHCl + 5 CS(NH

2)210mL Bars represent standard deviation for

two replicates

ions In order to achieve higher enrichment factor 4mL of5M HCl + 5 CS (NH

2)2was used for complete desorption

at an optimized eluent flow rate of 05mLmin (Figure 7)

353 Interferences As shown inmercury adsorption dynam-ics section the coexistence of equimolar metals with Hg(II)can prolong the equilibrium time due to the competitionbetween mercury and other metals towards the relevantbinding sites Therefore the effect of common interferingions on the adsorption of Hg(II) was examined using batchexperiment For that purpose 1 g of the studied resin wasequilibrated at pH 4 with 1mgL of Hg(II) and a certainconcentration of the interfering ion The mixture was shakenat 150 rpm and aliquots were taken at Hg equilibriumtime and analyzed using CV-AFS Results of Table 9 showed

0

20

40

60

80

100

120

Reco

very

()

1M H

Cl

1 th

iour

ea

1M H

Cl

2 th

iour

ea

1M H

Cl

3 th

iour

ea

1M H

Cl

4 th

iour

ea

5M H

Cl

5 th

iour

ea

2M H

NO3

4M H

Cl3M

HN

O3

Figure 6 Elution recovery of Hg(II) adsorbed on 5Ph8HQ bycolumnmethod using different types of eluents Conditions [Hg2+]2 ng mLminus1 volume 50mL pH 4 and eluent volume 10mL Barsrepresent standard deviation for two replicates

0

20

40

60

80

100

120

2 4 6 8 10

Reco

very

()

Volume eluent (mL)

5M HCl + 5 thiourea1MHCl + 2 thiourea

Figure 7 Effect of eluent volume on the recovery ofHg(II) adsorbedon 5Ph8HQ by column method Conditions [Hg2+] 2 ng mLminus1119881 (50mL) pH 4 and eluent 5M HCl + 5 CS (NH

2)21M HCl +

2 CS (NH2)2 Bars represent standard deviation for two replicates

that several thousand fold excess of KNaC4H4O6 Na2CO3

Na3C6H5O7 humic acid had minor effect on the extraction

of Hg(II) ions in which quantitative recoveries are stillattained Similarly 10ndash100-fold excess of anions and majorcompeting metals did not impose significant interferencesyet 4000-fold excess of Na

2C2O4and KCN have decreased


Table 7 Distribution coefficients of metals in single-metal solution at element-optimized pH

Element V Co Ni Cu Zn Cd Pb Mn Hg119870119889

1377 7998 595 1606 188 1998 24 9998 523

Table 8 Langmuir Freundlich and D-R isotherm constants of Hg

Metal Langmuir isotherms parameters Freundlich isotherms parameters D-R isotherms parameters119876119898(mmol gminus1) 119887 (Lmmolminus1) 119877

2119870119865(mmol gminus1) 119899 119877

2119876119898(mol gminus1) 119870 (mol2 KJminus2) 119877

2

Hg 00224 492815 09604 00311 61463 09064 0000039 1 times 10minus15 09446

Table 9 Effects of different electrolytes on the retention of Hg(II)ions

Electrolytes (cationanion) Foreign ion Recovery ()Na2CO3

a 875 954 plusmn 015

Na3C6H5O7a 864 959 plusmn 016

KNaC4H4O6a 2076 967 plusmn 021

Na2C2O4a 3007 942 plusmn 011

KCNa 4028 867 plusmn 022

Humic acidb 042 963 plusmn 014

SO42minusa 104 970 plusmn 037

Clminusa 282 959 plusmn 026

NO3minusa 161 969 plusmn 022

Fminusa 053 945 plusmn 014

Co2+a 136 991 plusmn 011

Fe3+a 143 970 plusmn 091

Ni2+a 136 991 plusmn 023

V4+a 157 992 plusmn 015

Cu2+a 126 983 plusmn 085

a mmol Lminus1 b g Lminus1

Table 10 Analytical results for the determination of Hg(II) innatural water samples by CV-AFS

Water samples Concentration 120583g Lminus1 Recovery ()Added Founda

Tap water0 0774 plusmn 0034

05 1274 plusmn 0082 1002 2769 plusmn 0066 998

River water0 0382 plusmn 0069

05 0882 plusmn 0085 1002 2380 plusmn 0055 999

aThe value following ldquoplusmnrdquo is the standard deviation (119899 = 2)

the Hg(II) retention to 94 and 87 respectively The latterhigh concentrations of 2ndash4 gL are rarely seen in aquaticenvironments which do not seem to impede the quantitativeextraction of mercury from river water matrix

354 Breakthrough Volume It is determined by using therecommended column procedure as described above usingincreasing volumes of Hg(II) solution while keeping the totalamount of Hg(II) in the solution constant at 2 120583g Resultshave shown that the maximum sample volume can be up

to 2000mL with the attainment of quantitative recovery andrelative standard deviation lt12 The quantitative recoveryof Hg(II) ions at high sample volumes is attributed to itshigh affinity and stability constant with 5Ph8HQ in whichmost resins fail in Hg(II) extraction from large volumes [13]Though a volume of 2000mLwas shown to extract effectivelyall target ions a volume of 1000mL was adopted for Hg(II)preconcentration in order to avoid long periods of extractiontime (119905 gt 8 hours) Considering 1000mL as the samplevolume and 4mL as the eluent volume an enrichment factorof 250 can be achieved

355 Analytical Performance and Applications The opti-mized method was applied for the extraction of trace levelsof Hg(II) ions in tap and river water samples A volume of1000mLwas spiked with varying quantities of 2 120583g and 05 120583gof Hg(II) Results shown in Table 10 show that Hg(II) spikeswere quantitatively extracted from both tap and river waterAs shown in pH section of the adsorption dynamics V(II)Cu(II) Ni(II) Co(II) and Zn(II) could be simultaneouslyextracted with Hg(II) ions at pH 4 Previous studies havereported a simultaneous extraction of metals at pH 6ndash8 [35ndash38 67] For this purpose 1000mL of tap water was spikedwith 2120583gL of a multielement mixture containing V(II)Cu(II) Ni(II) Co(II) and Hg(II) and percolated at pH 4through 300mg 5Ph8HQ eluted using 4mL of 5M HCl +5 CS (NH

2)2 and analyzed using ICP-MS for metals and

CV-AFS for Hg(II) ions Tables 10 and 11 demonstrate simul-taneous quantitative extraction ofV(II) Cu(II)Ni(II)Co(II)and Hg(II) at pH 4

The detection limit was calculated according to IUPAC[68] which is three times the standard deviation (3b) of eightruns of blank solution and was 021 ng Lminus1for Hg(II) usingCV-AFS The detection limit of ICP-MS was also calculatedfor V(II) Co(II) Ni(II) and Cu(II) and found to be 028 ngLminus1 04 ng Lminus1 15 ng Lminus1 and 11 ng Lminus1 respectively Therelative standard deviation (RSD) of 6 runs of 2 ng mLminus1Hg(II) was lower than 6 indicating a good precision of theanalytical method

4 Conclusion

The optimized method was compared to previously devel-oped analytical techniques for the measurements of tracelevels of Hg(II) As can be seen from Table 12 the precon-centration factor is high in comparison to other methods


Table 11 Simultaneous determination of metals in natural water samples by ICP-MS at pH 4

Water samples Element Concentration 120583g Lminus1 Recovery ()Added Founda

Tap water

V 0 0320 plusmn 0106

2 2315 plusmn 021 998

Co 0 0059 plusmn 0004

2 2041 plusmn 002 991

Ni 0 4392 plusmn 0037

2 6172 plusmn 005 965

Cu 0 0762 plusmn 0137

2 2759 plusmn 032 999

River water

V 0 0606 plusmn 0428

2 2602 plusmn 052 998

Co 0 0041 plusmn 0014

2 2030 plusmn 005 994

Ni 0 2964 plusmn 0377

2 4790 plusmn 052 964

Cu 0 0066 plusmn 042

2 2065 plusmn 032 999aThe value following ldquoplusmnrdquo is the standard deviation (119899 = 2)

Table 12 Comparison of figures of merits for different preconcentration methods for Hg(II) ion

Chelating resin DTa pH Capacity(mmolsdotgminus1) LODb

(pgsdotmLminus1) PFc Referenced

(1) poly(acrylamide) grafted onto cross-linkedpoly(4-vinyl pyridine) (P4-VP-g-PAm) AFS 1ndash8 41 2 20 [9]

(2) Silica gel2-thiophenecarboxaldehyde AAS 2 2 475 1000 [10](3) Sodium dodecyl sulphate-coated magnetitenanoparticlesMichlerrsquos Thioketone complexes ICP-AES 3 mdash 40 1230 [11]

(4)Magnetic nanoparticles doped with15-diphenylcarbazide CV-AAS 6 022 160 100 [12]

(5) Poly-allylthiourea CV-AAS 2 11 80 160 [13](6) Silica gel2-(2-oxoethyl)hydrazine ICP-AES 4 018 100 50 [14]

(7) Polyaniline (PANI) goldtrap-CVAAS 1ndash12 049 005 120 [15]

(8)Hg(II)-Ionic imprinted polymers-thymine AFS 8 0014 30 200 [16](9) Silica gelcysteine CV-AAS 1ndash7 069 15 40 [17](10) Aluminadimethylsulfoxide AAS 1-2 381 mdash 1000 [18](11)C18Isopropyl2-[(isopropoxycarbothioly)disulfany]ethanethioate

CV-AAS 3ndash7 0015 5 gt150 [19]

(12)Hg(II)-imprinted ion polymer CV-AAS 8 0205 50 200 [20](13) Agar powder modified with2-mercaptobenzimidazole CV-AAS 2-3 189 20 100 [21]

(14)Hg(II)-imprinted thiol-functionalizedmesoporous sorbent ICP-AES 4ndash8 0022 390 150 [22]

(15) Silica gel immobilized5-phenylazo-8-hydroxyquinoline CV-AFS 4 0027 021 gt250 This workaDetection technique blimit of detection cpreconcentration factor dreference


Moreover LOD achieved by CV-AFS is also low as comparedto other reported techniques Even though the adsorptioncapacity of the studied resin is considered low it does notseem to restrict the objectives of the analytical techniquedeveloped that is recovery of trace levels of mercury Highadsorption capacities of resins are rather preferable forremoval studies of mercury

In summary 5Ph8HQ has been widely used for thepreconcentration of trace levels of metals It has been provento be robust and exhibiting excellent affinity towards tran-sition elements However it has not been examined for theextraction of mercury Therefore in this study we havereported the adsorption dynamics of mercury Results haveshown that it is totally absorbed by 5Ph8HQ within the first30 minutes of contact time with 119905

125 minutes following

Langmuir adsorptionmodel At pH 4 the affinity of mercuryis unchallenged by other metals except for Cu(II) whichhave shown higher119870

119889valueWith these latter characteristics

5Ph8HQ was examined for the preconcentration of tracelevels of Hg(II) The developed method showed quantitativerecoveries of Hg(II) with LOD = 021 pgmLminus1 and RSD = 3ndash6 using CV-AFS

Acknowledgment

The authors would like to thank David Dumoulin RomainDescamps (Universite Lille 1) and Abdel Boughriet (Univer-site drsquoArtois) for their technical assistance

References

[1] M Tian N Song D Wang et al ldquoApplications of thebinary mixture of sec-octylphenoxyacetic acid and 8-hydrox-yquinoline to the extraction of rare earth elementsrdquo Hydromet-allurgy vol 111-112 no 1 pp 109ndash113 2012

[2] F Malamas M Bengtsson and G Johansson ldquoOn-line tracemetal enrichment and matrix isolation in atomic absorp-tion spectrometry by a column containing immobilized 8-quinolinol in a flow-injection systemrdquo Analytica Chimica Actavol 160 pp 1ndash10 1984

[3] P Y T Chow and F F Cantwell ldquoCalcium sorption byimmobilized oxine and its use in determining free calcium ionconcentration in aqueous solutionrdquo Analytical Chemistry vol60 no 15 pp 1569ndash1573 1988

[4] M R Weaver and J M Harris ldquoIn situ fluorescence studies ofaluminum ion complexation by 8-hydroxyquinoline covalentlybound to silicardquo Analytical Chemistry vol 61 no 9 pp 1001ndash1010 1989

[5] M Howard H A Jurbergs and J A Holcombe ldquoComparisonof silica-immobilized poly(L-cysteine) and 8-hydroxyquinolinefor trace metal extraction and recoveryrdquo Journal of analyticalatomic spectrometry vol 14 no 8 pp 1209ndash1214 1999

[6] S CeruttiM F Silva J A Gasquez R A Olsina and L DMar-tinez ldquoOn-line preconcentrationdetermination of cadmium indrinking water on activated carbon using 8-hydroxyquinolinein a flow injection system coupled to an inductively coupledplasma optical emission spectrometerrdquo Spectrochimica Acta Bvol 58 no 1 pp 43ndash50 2003

[7] M A Marshall and H A Mottola ldquoSynthesis of silica-immobi-lized 8-quinolinol with (aminophenyl)trimethoxysilanerdquo Ana-lytical Chemistry vol 55 no 13 pp 2089ndash2093 1983

[8] R D Shannon ldquoeffective ionic radii and systematic studiesof interatomie distances in halides and chaleogenidesrdquo ActaCrystallographica A vol 32 pp 751ndash767 1976

[9] O Yayayuruk EHenden andN Bicak ldquoDetermination ofmer-cury(ii) in the presence of methylmercury after preconcentra-tion using poly(acrylamide) grafted onto cross-linked poly(4-vinyl pyridine) application to mercury speciationrdquo AnalyticalSciences vol 27 no 8 pp 833ndash838 2011

[10] E M Soliman M B Saleh and S A Ahmed ldquoNew solidphase extractors for selective separation and preconcentrationofmercury (II) based on silica gel immobilized aliphatic amines2-thiophenecarboxaldehyde Schiff rsquos basesrdquo Analytica ChimicaActa vol 523 no 1 pp 133ndash140 2004

[11] M Faraji Y Yamini and M Rezaee ldquoExtraction of traceamounts of mercury with sodium dodecyle sulphate-coatedmagnetite nanoparticles and its determination by flow injectioninductively coupled plasma-optical emission spectrometryrdquoTalanta vol 81 no 3 pp 831ndash836 2010

[12] Y Zhai S Duan Q He X Yang and Q Han ldquoSolid phaseextraction and preconcentration of trace mercury(II) fromaqueous solution using magnetic nanoparticles doped with 15-diphenylcarbaziderdquoMicrochimica Acta vol 169 no 3 pp 353ndash360 2010

[13] W Qu Y Zhai S Meng Y Fan and Q Zhao ldquoSelective solidphase extraction and preconcentration of trace mercury(II)with poly-allylthiourea packed columnsrdquo Microchimica Actavol 163 no 3-4 pp 277ndash282 2008

[14] X Chai X Chang Z Hu Q He Z Tu and Z Li ldquoSolidphase extraction of traceHg(II) on silica gelmodifiedwith 2-(2-oxoethyl)hydrazine carbothioamide and determination by ICP-AESrdquo Talanta vol 82 no 5 pp 1791ndash1796 2010

[15] MV B KrishnaDKarunasagar S V Rao and J ArunachalamldquoPreconcentration and speciation of inorganic and methylmercury in waters using polyaniline and gold trap-CVAASrdquoTalanta vol 68 no 2 pp 329ndash335 2005

[16] S Xu L Chena J Li Y Guan and H Lu ldquoNovel Hg2+-imprinted polymers based on thymine-Hg2+-thymine interac-tion for highly selective preconcentration of Hg2+ in watersamplesrdquo Journal of Hazardous Materials vol 237-238 pp 347ndash354 2012

[17] E K Mladenova I G Dakova D L Tsalev and I B KaradjovaldquoMercury determination and speciation analysis in surfacewatersrdquoCentral European Journal of Chemistry vol 10 pp 1175ndash1182 2012

[18] E M Soliman M B Saleh and S A Ahmed ldquoAluminamodified by dimethyl sulfoxide as a new selective solid phaseextractor for separation and preconcentration of inorganicmercury(II)rdquo Talanta vol 69 no 1 pp 55ndash60 2006

[19] M Shamsipur A ShokrollahiH Sharghi andMM EskandarildquoSolid phase extraction and determination of sub-ppb levels ofhazardous Hg2+ ionsrdquo Journal of Hazardous Materials vol 117no 2-3 pp 129ndash133 2005

[20] Y Liu X ChangD Yang YGuo and SMeng ldquoHighly selectivedetermination of inorganic mercury(II) after preconcentra-tion with Hg(II)-imprinted diazoaminobenzene-vinylpyridinecopolymersrdquo Analytica Chimica Acta vol 538 no 1-2 pp 85ndash91 2005

[21] N Pourreza and K Ghanemi ldquoDetermination of mercuryin water and fish samples by cold vapor atomic absorption


spectrometry after solid phase extraction on agarmodified with2-mercaptobenzimidazolerdquo Journal ofHazardousMaterials vol161 no 2-3 pp 982ndash987 2009

[22] Z Fan ldquoHg(II)-imprinted thiol-functionalized mesoporoussorbent micro-column preconcentration of trace mercury anddetermination by inductively coupled plasma optical emissionspectrometryrdquo Talanta vol 70 no 5 pp 1164ndash1169 2006

[23] J M Hill ldquoSilica gel as an insoluble carrier for the preparationof selective chromatographic adsorbents The preparation of 8-hydroxyquinonline substituted silica gel for the chelation chro-matography of some trace metalsrdquo Journal of ChromatographyA vol 76 no 2 pp 455ndash458 1973

[24] M A Marshall and H A Mottola ldquoPerformance studies underflow conditions of silica-immobilized 8-quinolinol and itsapplication as a preconcentration tool in flow injectionatomicabsorption determinationsrdquo Analytical Chemistry vol 57 no 3pp 729ndash733 1985

[25] J R Jezorek K H Faltynski L G Blackburn P J Hendersonand H D Medina ldquoSilica-bound complexing agents someaspects of synthesis stability and pore sizerdquo Talanta vol 32 no8 pp 763ndash770 1985

[26] A Goswami A K Singh and B Venkataramani ldquo8-Hydrox-yquinoline anchored to silica gel via new moderate size linkersynthesis and applications as ametal ion collector for their flameatomic absorption spectrometric determinationrdquo Talanta vol60 pp 1141ndash1154 2003

[27] U Pyell and G Stork ldquoPreparation and properties of an 8-hydroxyquinoline silica gel synthesized via mannich reactionrdquoFreseniusrsquo Journal of Analytical Chemistry vol 342 no 4-5 pp281ndash286 1992

[28] M Luhrmann N Stelter and A Kettrup ldquoSynthesis andproperties of metal collecting phases with silica immobi-lized 8-Hydroxyquinolinerdquo Freseniusrsquo Zeitschrift fur AnalytischeChemie vol 322 no 1 pp 47ndash52 1985

[29] V A Tertykh V V Yanishpolskii and O Y Panova ldquoCovalentattachment of some phenol derivatives to the silica surfaceby use of single-stage aminomethylationrdquo Journal of ThermalAnalysis and Calorimetry vol 62 no 2 pp 545ndash549 2000

[30] Z Wang M Jing F S C 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 of Analyt-ical Chemistry vol 34 no 4 pp 459ndash463 2006

[31] RHUibel and JMHarris ldquoIn situ raman spectroscopy studiesof metal ion complexation by 8-hydroxyquinoline covalentlybound to silica surfacesrdquo Analytical Chemistry vol 74 no 19pp 5112ndash5120 2002

[32] R H Uibel and J M Harris ldquoSpectroscopic studies of proton-transfer and metal-ion binding of a solution-phase modelfor silica-immobilized 8-hydroxyquinolinerdquo Analytica ChimicaActa vol 494 no 1-2 pp 105ndash123 2003

[33] M Hebrant M Rose-Helene and A Walcarius ldquoMetal ionremoval by ultrafiltration of colloidal suspensions of organicallymodified silicardquo Colloids and Surfaces A vol 417 pp 65ndash722013

[34] K F Sugawara HHWeetall andGD Schucker ldquoPreparationproperties and applications of 8-hydroxyquinoline immobi-lized chelaterdquo Analytical Chemistry vol 46 no 4 pp 489ndash4921974

[35] R E Sturgeon S S Berman S NWillie and J A H Desauini-ers ldquoPreconcentration of trace elements from seawater with

silica-immobilized 8-hydroxyquinolinerdquo Analytical Chemistryvol 53 no 14 pp 2337ndash2340 1981

[36] J W McLaren ldquoDetermination of trace metals in seawater byinductively coupled plasmamass spectrometrywith preconcen-tration on silica-immobilized 8-hydroxyquinolinerdquo AnalyticalChemistry vol 57 no 14 pp 2907ndash2911 1985

[37] B K Esser A Volpe J M Kenneally and D K Smith ldquoPre-concentration and purification of rare earth elements in natu-ral waters using silica-immobilized 8-hydroxyquinoline and asupported organophosphorus extractantrdquoAnalytical Chemistryvol 66 no 10 pp 1736ndash1742 1994

[38] S M Nelms G M Greenway and R C Hutton ldquoApplicationof multi-element time-resolved analysis to a rapid on-linematrix separation system for inductively coupled plasma massspectrometryrdquo Journal of Analytical Atomic Spectrometry vol10 no 11 pp 929ndash933 1995

[39] B L Rivas B Urbano S A Pooley I Bustos and N EscalonaldquoMercury and lead sorption properties of poly(ethyleneimine)coated onto silica gelrdquo Polymer Bulletin vol 68 pp 1577ndash15882012

[40] S Lagergren ldquoZur theorie der sogenannten adsorption gelosterstofferdquo Kungliga Svenska Vetenskapsakademiens Handlingarvol 24 no 4 pp 1ndash39 1898

[41] Y S Ho and G McKay ldquoPseudo-second order model forsorption processesrdquo Process Biochemistry vol 34 no 5 pp 451ndash465 1999

[42] W J Weber and J C Morris ldquoKinetics of adsorption on carbonfrom solutionrdquo Journal of the Sanitary Engineering Division vol89 no 2 pp 31ndash60 1963

[43] H Freundlich ldquoUeber die adsorption in loesungenrdquo Zeitschriftfur Physikalische Chemie vol 57 pp 385ndash470 1907

[44] H Dikici and K Salti ldquoEquiliberium and kinetics characteris-tics of copper(II) sorption into gytijardquo Bulletin of EnvironmentalContamination and Toxicology vol 84 pp 147ndash151 2010

[45] M M Dubinin and L V Raudushkevich ldquoEquation of thecharacteristics curve of activated charcoalrdquo Proceedings of theAcademy of Sciences Physical Chemistry Section USSR vol 55pp 331ndash333 1947

[46] M L Ferreira and M E Gschaider ldquoTheoretical and experi-mental study of Pb2+ and Hg2+ adsorption on biopolymers 1theoretical studyrdquo Macromolecular Bioscience vol 1 no 6 pp233ndash248 2001

[47] A W Adamson Physical Chemistry of Surfaces Wiley NewYork NY USA 5th edition 1990

[48] A E Martell and L G Sillen Stability Constants of Metal IonComplexes Chemical Society London UK 2nd edition 1964

[49] D R TurnerMWhitfield andAGDickson ldquoThe equilibriumspeciation of dissolved components in freshwater and sea waterat 25∘C and 1 atm pressurerdquo Geochimica et Cosmochimica Actavol 45 no 6 pp 855ndash881 1981

[50] W T Rees ldquoFluorimetric determination of very small amountsof aluminiumrdquoThe Analyst vol 87 no 1032 pp 202ndash206 1962

[51] K-L Yang S-J Jiang and T-J Hwang ldquoDetermination oftitanium and vanadium inwater samples by inductively coupledplasma mass spectrometry with on-line preconcentrationrdquoJournal of Analytical Atomic Spectrometry vol 11 no 2 pp 139ndash143 1996

[52] J R Dojlido and G A Best Chemistry of Water and WaterPollution Ellis Horwood Series in Water and WastewaterTechnology Ellis Horwood New York NY USA 1993


[53] A Denizli K Kesenci Y Arica and E Piskin ldquoDithiocarbam-ate-incorporated monosize polystyrene microspheres for selec-tive removal of mercury ionsrdquo Reactive and Functional Poly-mers vol 44 no 3 pp 235ndash243 2000

[54] P Stathi K Dimos M A Karakassides and Y DeligiannakisldquoMechanism of heavy metal uptake by a hybrid MCM-41material surface complexation and EPR spectroscopic studyrdquoJournal of Colloid and Interface Science vol 343 no 1 pp 374ndash380 2010

[55] V C Taty-Costodes H Fauduet C Porte and A DelacroixldquoRemoval of Cd(II) and Pb(II) ions from aqueous solutionsby adsorption onto sawdust of Pinus sylvestrisrdquo Journal ofHazardous Materials vol 105 no 1ndash3 pp 121ndash142 2003

[56] M V Dinu and E S Dragan ldquoEvaluation of Cu2+ Co2+ andNi2+ ions removal from aqueous solution using a novel chi-tosanclinoptilolite composite kinetics and isothermsrdquo Chemi-cal Engineering Journal vol 160 no 1 pp 157ndash163 2010

[57] M Mureseanu A Reiss I Stefanescu et al ldquoModified SBA-15mesoporous silica for heavy metal ions remediationrdquo Chemo-sphere vol 73 no 9 pp 1499ndash1504 2008

[58] A Sayari S Hamoudi and Y Yang ldquoApplications of pore-expanded mesoporous silica 1 Removal of heavy metal cationsand organic pollutants from wastewaterrdquo Chemistry of Materi-als vol 17 no 1 pp 212ndash216 2005

[59] H Irving and R J P Williams ldquoOrder of stability of metalcomplexesrdquo Nature vol 162 no 4123 pp 746ndash747 1948

[60] A Benhamou M Baudu Z Derriche and J P Basly ldquoAqueousheavy metals removal on amine-functionalized Si-MCM-41and Si-MCM-48rdquo Journal of Hazardous Materials vol 171 no1ndash3 pp 1001ndash1008 2009

[61] N Unlu and M Ersoz ldquoAdsorption characteristics of heavymetal ions onto a low cost biopolymeric sorbent from aqueoussolutionsrdquo Journal of Hazardous Materials vol 136 no 2 pp272ndash280 2006

[62] L Wang R Xing S Liu et al ldquoSynthesis and evaluation of athiourea-modified chitosan derivative applied for adsorptionof Hg(II) from synthetic wastewaterrdquo International Journal ofBiological Macromolecules vol 46 no 5 pp 524ndash528 2010

[63] O Hakami Y Zhang and C J Banks ldquoThiol-functionalizedmesoporous silica-coated magnetite nanoparticles for highefficiency removal and recovery of Hg from waterrdquo WaterResearch vol 46 pp 3913ndash3922 2012

[64] L Bai H HuW Fu et al ldquoSynthesis of a novel silica-supporteddithiocarbamate adsorbent and its properties for the removal ofheavy metal ionsrdquo Journal of Hazardous Materials vol 195 pp261ndash275 2011

[65] L Qi and Z Xu ldquoLead sorption from aqueous solutions onchitosan nanoparticlesrdquo Colloids and Surfaces A vol 251 no 1ndash3 pp 183ndash190 2004

[66] S N Willie H Tekgul and R E Sturgeon ldquoImmobilization of8-hydroxyquinoline onto silicone tubing for the determinationof trace elements in seawater using flow injection ICP-MSrdquoTalanta vol 47 no 2 pp 439ndash445 1998

[67] H Watanabe K Goto S Taguchi J W McLaren S S Bermanand D S Russell ldquoPreconcentration of trace elements in seawa-ter by complexation with 8-hydroxyquinoline and adsorptionon C18 bonded silica gelrdquo Analytical Chemistry vol 53 no 4pp 738ndash739 1981

[68] G L Long and J D Winefordner ldquoLimit of detection a closerlook at the IUPAC definitionrdquo Analytical Chemistry vol 55 no7 pp 712ndash724 1983


matrices from XAD to activated carbon [6] Adsorptioncapacities have been determined for some metals that isCu(II) using 8-HQ functionalized CPG 58 120583moleg PorasilC porous silica 104 120583moleg and silica gel 216 120583moleg Itis evident that silica gel confers the largest capacity withan average molar coverage of 039 120583molem2 attributed toincreased surface area of 55384m2g (decreased pore size)[7]

Numerous synthesis routes have been described since thefirst immobilization of 8-hydroxyquinoline (8-HQ) on silicagel Diazo coupling of 8-HQ with p-aminobenzamide propylsilica was first reported in [23 34] The first techniques werefurther ameliorated by diazo coupling of 8-HQ on p-aminophenyl silica [24] or glass [25] Moreover the formation ofSchiff rsquos base on position 5 of 8-HQmoiety enables its fixationon p-aminopropyl silica bestowing extraordinary coordina-tion [26] Finally following the Mannich reaction whichoffers two possible procedures of 8-HQ immobilization onsilica phase one involving two steps reactions [27 28] andthe other one-step reaction [29 30] Among these synthesisroutes immobilization involving the diazo coupling of 8-HQ on p-aminobenzamide propyl silica was shown by manystudies to have an excellent retention of many trace metalsThe most powerful chelating 8-HQ-grafted silica is that withan exceptional coordination potential given by its anchoringposition on carbon 5 of 8-HQ moiety Therefore phenylazo-8-HQ was chosen in this study among other 8-HQ-5-graftedsilica due its higher yield product

Since then much research has been conducted tofully understand the complexing ability of phenylazo-8-HQ(5Ph8HQ) Spectroscopic studies of metal complexes with5Ph8HQ bound to silica showed 1 1 metal ligand stoichi-ometry in Cu2+ solution complex [31] Other studies havedetermined the protonation constants of 5Ph8HQ-graftedsilica to be 119901119870119886

1= 27 and 119901119870119886

2= 86 [31] However the

water soluble sulfo-derivative of 8-HQ 5-(p-sulfophenylazo)-8-hydroxyquinoline showed higher acid dissociation con-stants pKa

1of 378 and pKa

2of 794 [32] These values

would certainly change when the ligand is bound on silicaEquilibrium constants for 5Ph8HQ silica binding to metalshave been determined The stability constant of Cu2+ withthe grafted material was 119870∘ = 48 times 10

8 [31] showing higherstability constant with Sulfo-5Ph8HQ in water119870 = 14times10

10

[32] Recent study has showed higher equilibrium constantfor Cu2+ than the previously reported ones for 5Ph8HQ inmicelles and colloidal fumed silica-5Ph8HQ119870∘ = 127times10

11

and 119870∘

= 7 times 1011 respectively [33] Stability constant for

Ni2+ was also determined and found to beKrsquoext = 59 [24] andKrsquoext = 08ndash12 for 1 1 ligandmetal stoichiometry in presenceof either acetate or chloride counter ion [33] Stabilityconstants of metals with 8-HQ immobilized silica accordingto Luhrmann et al [28] protocol were also determinedwhich involved the functionalization of p-aminopropyl silicawith 5-chloro-methyl-8-hydroxyquinoline Using Luhrmannprotocol distribution ratios log119870

119863were determined for

many metals including Cu Ni Co Fe Mn Cr Zn CdHg and Pb using batch equilibrium technique for 8-HQ-grafted silica The use of the former protocol is not widely

studied because of its extremely high cost Many studieshave used 5Ph8HQ for the retention and preconcentrationof metals with excellent recoveries [5 34ndash38] Neverthelessthe adsorption dynamics of 5Ph8HQ-grafted silica is notcompletely studied particularly for mercury Thus in thisstudy we attempt to study the adsorption kinetics of mer-cury in single- and multielement solution to discover thecompetition demonstrated between mercury and differentmetals for 5Ph8HQ affinity sites Moreover in this studyadsorption isotherms of mercury and other metals weredetermined for 5Ph8HQ Finally an analytical method forthe determination of Hg(II) in river water was developedbased on 5Ph8HQ-linked silica as adsorbent and Cold VaporAtomic Fluorescence Spectroscopy (CV-AFS) as an analyticalinstrument

2 Materials and Methods

21 Chemicals and Materials

211 Reagents and Apparatus Analytical reagent-gradechemicals were used and obtained Sigma Aldrich (France)Ultrapure water (with a resistivity of 182 MΩ) was obtainedusing a Milli-Q system (Millipore USA) Silica (100ndash200mesh) chemicals and solvents were supplied fromSigma Aldrich (France) Labware was soaked in 20 nitricacid and washed thoroughly with pure water prior to useWorking solutions of metals ions (Cr(III) Cu(II) Co(II)Zn(II) Ni(II) Pb(II) Cd(II) As(II) Fe(III) V(II) andHg(II)) were prepared from stock metal nitrate solution(1000mgL) (Merck) Buffer solutions were prepared from1M sodium acetate to which different volumes of 1M nitricacid were added to obtain pH in the range 4ndash6 Ammoniumacetate and phosphate buffer were used for obtaining pH 7and pH 8 respectively

Fourier transform infrared (FT-IR) spectra of functional-ized silica were recorded using Nicolet 380 Smart iTR spec-trometer (ThermoScientific USA) and were silica-matrixcorrected An inductively coupled plasma mass spectrom-eter Thermo-Optek X7 (Thermo Fischer Scientific USA)equipped with a cross-flow pneumatic nebulizer a concentricglass-type nebulization chamber and a 15mm id quartzplasma torch was used All the operating parameters werethose recommended by the manufacturer The optimumoperating conditions and measurement parameters for ICP-MS are listed in Table 1 Measurements were performed withhigh-purity Argon gas The pH measurements and adjust-ments were conducted by pHmeter (Thermo ScientificOrionStar A111 USA) The flow rates of the samples were adjustedusing a Gilson Miniplus 3 peristaltic pump PVC tubes(318 id) were used for the preconcentration process Self-made PTFE (polytetrafluoroethylene) columns (65mm times

4mm id) were used for packing the examined adsorbentMercury was measured by cold vapor atomic fluorescencespectroscopy (Tekran Model 2600 CVAFSMercury AnalysisSystem USA) Ionic mercury is reduced with SnCl

2(2

solution in 1 HCl) subsequently converted from Hg(II)to Hg∘ The volatile species of mercury are separated from












Sorption () =

119862119894minus 119862eq

119862119894

times 100 (1)

119876 =

(119862119894minus 119862eq)119881

119898 (2)

119870119889=

119876

119862eq (3)

120572 =119870119889(Hg (II))119870119889(119883)

(4)

11990512

=1

1198702119876eq

(5)








1198701119905

2303 (6)


0

20

40

60

80

100

120

0 2 4 6 8 10

Reco

very

()

pH








1

119876119905

=1

11987021198762eq

+ (1

119876eq) 119905 (7)




119876119905= 11987011989411990512

(8)


gsdotmin05)


1

119876eq=

1

119876119898

+1

119887119876119898119862eq

(9)




Log119876eq = log119870119865+

1

119899 log119862eq (10)





ln119876 = ln119876119898

minus 1198701205762 (11)





3


3Suprapur solution





2or soluble




Hg(H2O)6

2+


+H+ (12)


2and HgCl

4

2minus HgCl3



3)2


2 CdCl

3

minusand CdCl

4



2 and Cd(OH)

3








2

2+ andVO(OH)


H2VO4


2minus


4





020406080

100120

Reco

very

()

Mercury


0times10

2

(a)

Vanadium


020406080

100120

0times10

2

(b)

Cobalt


020406080

100120

0times10

2

(c)

020406080

100120

Reco

very

()

Nickel


0times10

2

(d)

Lead


020406080

100120

0times10

2

(e)

Manganese


020406080

100120

0times10

2

(f)

020406080

100120

0 5 10 15 20

Reco

very

()

Contact time (min)

Cadmium

times102

(g)


Copper

020406080

100120

0times10

2

(h)


Zinc

020406080

100120

times102

(i)





1was







119905versus 119905


119905versus



00 100 200 300 400 500

Time (min)

minus2

minus4

minus6

R2= 09641

log(QeminusQt)

(a)

0400000800000

12000001600000

0 500 1000 1500 2000Time (min)

R2= 1

tQt

(min

gm

moL

minus1)

(b)

000093000095000097000099000101

0 10 20 30 40

t12 (min)

R2= 07665

Qt

(mm

oLg

minus1)

(c)

020406080

100120

0 200 400 600 800

R2= 09604

1Qe

(gm

moL

minus1)



log Qe

minus05

minus1

minus15

minus2

minus25

R2= 09064

log Ce

(e)

0 2000000001205762

R2= 09446

minus124

minus12

minus116

minus112

minus108

minus104

lnQe

(f)





1(minminus1) 119877

2 119876119890



11990512

119870119894

1198772













119889Cu(II) 14548 gt 119870

119889Hg(II) 50 and 120572 lt 1






0

0005

001

0015

002

0025

0 50 100 150


Qe

(mm

oLg

minus1)













1(minminus1) 119877

2 119876119890



11990512

119870119894

1198772

Co 000146 000230 09533 000255 3283 0991 11961 000004 09427V 000007 000299 08843 000390 137896 1 186 0000003 04423Cu 000004 000484 08318 000315 420290 1 076 0000001 06093Zn 000033 000553 09541 000096 41447 09998 2504 0000009 06659Ni 000161 000345 09552 000267 4169 09987 8983 000004 07309Fe 000193 000161 07571 000350 2302 09993 12409 0000008 03698Hg 000024 000668 07452 000100 68596 09998 1452 0000009 04446



2512 048 058 15365 005 002 003 326 4976120572 119870119889Hg119870

119889M+ 198 10287 8599 032 93116 263832 146879 1528 mdash





119877119871=

1

1 + 119870119871119862119894

(13)






119871= 0 the



119871value lt 01








2)2]


2)2




V Cu Ni Co Fe Hg119870119889

27011 159800 12829 35836 5260 52376120572 119870119889Hg119870

119889M+ 1939 03278 40825 1462 9957 mdash




0

20

40

60

80

100

120

0 2 4 6

Reco

very

()




two replicates





0

20

40

60

80

100

120

Reco

very

()

1M H

Cl

1 th

iour

ea

1M H

Cl

2 th

iour

ea

1M H

Cl

3 th

iour

ea

1M H

Cl

4 th

iour

ea

5M H

Cl

5 th

iour

ea

2M H

NO3

4M H

Cl3M

HN

O3


0

20

40

60

80

100

120

2 4 6 8 10

Reco

very

()

Volume eluent (mL)



2)21M HCl +









1377 7998 595 1606 188 1998 24 9998 523



2119870119865(mmol gminus1) 119899 119877


2

Hg 00224 492815 09604 00311 61463 09064 0000039 1 times 10minus15 09446



a 875 954 plusmn 015



Na2C2O4a 3007 942 plusmn 011







Co2+a 136 991 plusmn 011

Fe3+a 143 970 plusmn 091

Ni2+a 136 991 plusmn 023

V4+a 157 992 plusmn 015

Cu2+a 126 983 plusmn 085





05 1274 plusmn 0082 1002 2769 plusmn 0066 998


05 0882 plusmn 0085 1002 2380 plusmn 0055 999









4 Conclusion





Tap water

V 0 0320 plusmn 0106

2 2315 plusmn 021 998

Co 0 0059 plusmn 0004

2 2041 plusmn 002 991

Ni 0 4392 plusmn 0037

2 6172 plusmn 005 965

Cu 0 0762 plusmn 0137

2 2759 plusmn 032 999

River water

V 0 0606 plusmn 0428

2 2602 plusmn 052 998

Co 0 0041 plusmn 0014

2 2030 plusmn 005 994

Ni 0 2964 plusmn 0377

2 4790 plusmn 052 964












CV-AAS 3ndash7 0015 5 gt150 [19]











Acknowledgment


References




















































































Sorption () =

119862119894minus 119862eq

119862119894

times 100 (1)

119876 =

(119862119894minus 119862eq)119881

119898 (2)

119870119889=

119876

119862eq (3)

120572 =119870119889(Hg (II))119870119889(119883)

(4)

11990512

=1

1198702119876eq

(5)








1198701119905

2303 (6)


0

20

40

60

80

100

120

0 2 4 6 8 10

Reco

very

()

pH








1

119876119905

=1

11987021198762eq

+ (1

119876eq) 119905 (7)




119876119905= 11987011989411990512

(8)


gsdotmin05)


1

119876eq=

1

119876119898

+1

119887119876119898119862eq

(9)




Log119876eq = log119870119865+

1

119899 log119862eq (10)





ln119876 = ln119876119898

minus 1198701205762 (11)





3


3Suprapur solution





2or soluble




Hg(H2O)6

2+


+H+ (12)


2and HgCl

4

2minus HgCl3



3)2


2 CdCl

3

minusand CdCl

4



2 and Cd(OH)

3








2

2+ andVO(OH)


H2VO4


2minus


4





020406080

100120

Reco

very

()

Mercury


0times10

2

(a)

Vanadium


020406080

100120

0times10

2

(b)

Cobalt


020406080

100120

0times10

2

(c)

020406080

100120

Reco

very

()

Nickel


0times10

2

(d)

Lead


020406080

100120

0times10

2

(e)

Manganese


020406080

100120

0times10

2

(f)

020406080

100120

0 5 10 15 20

Reco

very

()

Contact time (min)

Cadmium

times102

(g)


Copper

020406080

100120

0times10

2

(h)


Zinc

020406080

100120

times102

(i)





1was







119905versus 119905


119905versus



00 100 200 300 400 500

Time (min)

minus2

minus4

minus6

R2= 09641

log(QeminusQt)

(a)

0400000800000

12000001600000

0 500 1000 1500 2000Time (min)

R2= 1

tQt

(min

gm

moL

minus1)

(b)

000093000095000097000099000101

0 10 20 30 40

t12 (min)

R2= 07665

Qt

(mm

oLg

minus1)

(c)

020406080

100120

0 200 400 600 800

R2= 09604

1Qe

(gm

moL

minus1)



log Qe

minus05

minus1

minus15

minus2

minus25

R2= 09064

log Ce

(e)

0 2000000001205762

R2= 09446

minus124

minus12

minus116

minus112

minus108

minus104

lnQe

(f)





1(minminus1) 119877

2 119876119890



11990512

119870119894

1198772













119889Cu(II) 14548 gt 119870

119889Hg(II) 50 and 120572 lt 1






0

0005

001

0015

002

0025

0 50 100 150


Qe

(mm

oLg

minus1)













1(minminus1) 119877

2 119876119890



11990512

119870119894

1198772

Co 000146 000230 09533 000255 3283 0991 11961 000004 09427V 000007 000299 08843 000390 137896 1 186 0000003 04423Cu 000004 000484 08318 000315 420290 1 076 0000001 06093Zn 000033 000553 09541 000096 41447 09998 2504 0000009 06659Ni 000161 000345 09552 000267 4169 09987 8983 000004 07309Fe 000193 000161 07571 000350 2302 09993 12409 0000008 03698Hg 000024 000668 07452 000100 68596 09998 1452 0000009 04446



2512 048 058 15365 005 002 003 326 4976120572 119870119889Hg119870

119889M+ 198 10287 8599 032 93116 263832 146879 1528 mdash





119877119871=

1

1 + 119870119871119862119894

(13)






119871= 0 the



119871value lt 01








2)2]


2)2




V Cu Ni Co Fe Hg119870119889

27011 159800 12829 35836 5260 52376120572 119870119889Hg119870

119889M+ 1939 03278 40825 1462 9957 mdash




0

20

40

60

80

100

120

0 2 4 6

Reco

very

()




two replicates





0

20

40

60

80

100

120

Reco

very

()

1M H

Cl

1 th

iour

ea

1M H

Cl

2 th

iour

ea

1M H

Cl

3 th

iour

ea

1M H

Cl

4 th

iour

ea

5M H

Cl

5 th

iour

ea

2M H

NO3

4M H

Cl3M

HN

O3


0

20

40

60

80

100

120

2 4 6 8 10

Reco

very

()

Volume eluent (mL)



2)21M HCl +









1377 7998 595 1606 188 1998 24 9998 523



2119870119865(mmol gminus1) 119899 119877


2

Hg 00224 492815 09604 00311 61463 09064 0000039 1 times 10minus15 09446



a 875 954 plusmn 015



Na2C2O4a 3007 942 plusmn 011







Co2+a 136 991 plusmn 011

Fe3+a 143 970 plusmn 091

Ni2+a 136 991 plusmn 023

V4+a 157 992 plusmn 015

Cu2+a 126 983 plusmn 085





05 1274 plusmn 0082 1002 2769 plusmn 0066 998


05 0882 plusmn 0085 1002 2380 plusmn 0055 999









4 Conclusion





Tap water

V 0 0320 plusmn 0106

2 2315 plusmn 021 998

Co 0 0059 plusmn 0004

2 2041 plusmn 002 991

Ni 0 4392 plusmn 0037

2 6172 plusmn 005 965

Cu 0 0762 plusmn 0137

2 2759 plusmn 032 999

River water

V 0 0606 plusmn 0428

2 2602 plusmn 052 998

Co 0 0041 plusmn 0014

2 2030 plusmn 005 994

Ni 0 2964 plusmn 0377

2 4790 plusmn 052 964












CV-AAS 3ndash7 0015 5 gt150 [19]











Acknowledgment


References










































































0

20

40

60

80

100

120

0 2 4 6 8 10

Reco

very

()

pH








1

119876119905

=1

11987021198762eq

+ (1

119876eq) 119905 (7)




119876119905= 11987011989411990512

(8)


gsdotmin05)


1

119876eq=

1

119876119898

+1

119887119876119898119862eq

(9)




Log119876eq = log119870119865+

1

119899 log119862eq (10)





ln119876 = ln119876119898

minus 1198701205762 (11)





3


3Suprapur solution





2or soluble




Hg(H2O)6

2+


+H+ (12)


2and HgCl

4

2minus HgCl3



3)2


2 CdCl

3

minusand CdCl

4



2 and Cd(OH)

3








2

2+ andVO(OH)


H2VO4


2minus


4





020406080

100120

Reco

very

()

Mercury


0times10

2

(a)

Vanadium


020406080

100120

0times10

2

(b)

Cobalt


020406080

100120

0times10

2

(c)

020406080

100120

Reco

very

()

Nickel


0times10

2

(d)

Lead


020406080

100120

0times10

2

(e)

Manganese


020406080

100120

0times10

2

(f)

020406080

100120

0 5 10 15 20

Reco

very

()

Contact time (min)

Cadmium

times102

(g)


Copper

020406080

100120

0times10

2

(h)


Zinc

020406080

100120

times102

(i)





1was







119905versus 119905


119905versus



00 100 200 300 400 500

Time (min)

minus2

minus4

minus6

R2= 09641

log(QeminusQt)

(a)

0400000800000

12000001600000

0 500 1000 1500 2000Time (min)

R2= 1

tQt

(min

gm

moL

minus1)

(b)

000093000095000097000099000101

0 10 20 30 40

t12 (min)

R2= 07665

Qt

(mm

oLg

minus1)

(c)

020406080

100120

0 200 400 600 800

R2= 09604

1Qe

(gm

moL

minus1)



log Qe

minus05

minus1

minus15

minus2

minus25

R2= 09064

log Ce

(e)

0 2000000001205762

R2= 09446

minus124

minus12

minus116

minus112

minus108

minus104

lnQe

(f)





1(minminus1) 119877

2 119876119890



11990512

119870119894

1198772













119889Cu(II) 14548 gt 119870

119889Hg(II) 50 and 120572 lt 1






0

0005

001

0015

002

0025

0 50 100 150


Qe

(mm

oLg

minus1)













1(minminus1) 119877

2 119876119890



11990512

119870119894

1198772

Co 000146 000230 09533 000255 3283 0991 11961 000004 09427V 000007 000299 08843 000390 137896 1 186 0000003 04423Cu 000004 000484 08318 000315 420290 1 076 0000001 06093Zn 000033 000553 09541 000096 41447 09998 2504 0000009 06659Ni 000161 000345 09552 000267 4169 09987 8983 000004 07309Fe 000193 000161 07571 000350 2302 09993 12409 0000008 03698Hg 000024 000668 07452 000100 68596 09998 1452 0000009 04446



2512 048 058 15365 005 002 003 326 4976120572 119870119889Hg119870

119889M+ 198 10287 8599 032 93116 263832 146879 1528 mdash





119877119871=

1

1 + 119870119871119862119894

(13)






119871= 0 the



119871value lt 01








2)2]


2)2




V Cu Ni Co Fe Hg119870119889

27011 159800 12829 35836 5260 52376120572 119870119889Hg119870

119889M+ 1939 03278 40825 1462 9957 mdash




0

20

40

60

80

100

120

0 2 4 6

Reco

very

()




two replicates





0

20

40

60

80

100

120

Reco

very

()

1M H

Cl

1 th

iour

ea

1M H

Cl

2 th

iour

ea

1M H

Cl

3 th

iour

ea

1M H

Cl

4 th

iour

ea

5M H

Cl

5 th

iour

ea

2M H

NO3

4M H

Cl3M

HN

O3


0

20

40

60

80

100

120

2 4 6 8 10

Reco

very

()

Volume eluent (mL)



2)21M HCl +









1377 7998 595 1606 188 1998 24 9998 523



2119870119865(mmol gminus1) 119899 119877


2

Hg 00224 492815 09604 00311 61463 09064 0000039 1 times 10minus15 09446



a 875 954 plusmn 015



Na2C2O4a 3007 942 plusmn 011







Co2+a 136 991 plusmn 011

Fe3+a 143 970 plusmn 091

Ni2+a 136 991 plusmn 023

V4+a 157 992 plusmn 015

Cu2+a 126 983 plusmn 085





05 1274 plusmn 0082 1002 2769 plusmn 0066 998


05 0882 plusmn 0085 1002 2380 plusmn 0055 999









4 Conclusion





Tap water

V 0 0320 plusmn 0106

2 2315 plusmn 021 998

Co 0 0059 plusmn 0004

2 2041 plusmn 002 991

Ni 0 4392 plusmn 0037

2 6172 plusmn 005 965

Cu 0 0762 plusmn 0137

2 2759 plusmn 032 999

River water

V 0 0606 plusmn 0428

2 2602 plusmn 052 998

Co 0 0041 plusmn 0014

2 2030 plusmn 005 994

Ni 0 2964 plusmn 0377

2 4790 plusmn 052 964












CV-AAS 3ndash7 0015 5 gt150 [19]











Acknowledgment


References











































































Hg(H2O)6

2+


+H+ (12)


2and HgCl

4

2minus HgCl3



3)2


2 CdCl

3

minusand CdCl

4



2 and Cd(OH)

3








2

2+ andVO(OH)


H2VO4


2minus


4





020406080

100120

Reco

very

()

Mercury


0times10

2

(a)

Vanadium


020406080

100120

0times10

2

(b)

Cobalt


020406080

100120

0times10

2

(c)

020406080

100120

Reco

very

()

Nickel


0times10

2

(d)

Lead


020406080

100120

0times10

2

(e)

Manganese


020406080

100120

0times10

2

(f)

020406080

100120

0 5 10 15 20

Reco

very

()

Contact time (min)

Cadmium

times102

(g)


Copper

020406080

100120

0times10

2

(h)


Zinc

020406080

100120

times102

(i)





1was







119905versus 119905


119905versus



00 100 200 300 400 500

Time (min)

minus2

minus4

minus6

R2= 09641

log(QeminusQt)

(a)

0400000800000

12000001600000

0 500 1000 1500 2000Time (min)

R2= 1

tQt

(min

gm

moL

minus1)

(b)

000093000095000097000099000101

0 10 20 30 40

t12 (min)

R2= 07665

Qt

(mm

oLg

minus1)

(c)

020406080

100120

0 200 400 600 800

R2= 09604

1Qe

(gm

moL

minus1)



log Qe

minus05

minus1

minus15

minus2

minus25

R2= 09064

log Ce

(e)

0 2000000001205762

R2= 09446

minus124

minus12

minus116

minus112

minus108

minus104

lnQe

(f)





1(minminus1) 119877

2 119876119890



11990512

119870119894

1198772













119889Cu(II) 14548 gt 119870

119889Hg(II) 50 and 120572 lt 1






0

0005

001

0015

002

0025

0 50 100 150


Qe

(mm

oLg

minus1)













1(minminus1) 119877

2 119876119890



11990512

119870119894

1198772

Co 000146 000230 09533 000255 3283 0991 11961 000004 09427V 000007 000299 08843 000390 137896 1 186 0000003 04423Cu 000004 000484 08318 000315 420290 1 076 0000001 06093Zn 000033 000553 09541 000096 41447 09998 2504 0000009 06659Ni 000161 000345 09552 000267 4169 09987 8983 000004 07309Fe 000193 000161 07571 000350 2302 09993 12409 0000008 03698Hg 000024 000668 07452 000100 68596 09998 1452 0000009 04446



2512 048 058 15365 005 002 003 326 4976120572 119870119889Hg119870

119889M+ 198 10287 8599 032 93116 263832 146879 1528 mdash





119877119871=

1

1 + 119870119871119862119894

(13)






119871= 0 the



119871value lt 01








2)2]


2)2




V Cu Ni Co Fe Hg119870119889

27011 159800 12829 35836 5260 52376120572 119870119889Hg119870

119889M+ 1939 03278 40825 1462 9957 mdash




0

20

40

60

80

100

120

0 2 4 6

Reco

very

()




two replicates





0

20

40

60

80

100

120

Reco

very

()

1M H

Cl

1 th

iour

ea

1M H

Cl

2 th

iour

ea

1M H

Cl

3 th

iour

ea

1M H

Cl

4 th

iour

ea

5M H

Cl

5 th

iour

ea

2M H

NO3

4M H

Cl3M

HN

O3


0

20

40

60

80

100

120

2 4 6 8 10

Reco

very

()

Volume eluent (mL)



2)21M HCl +









1377 7998 595 1606 188 1998 24 9998 523



2119870119865(mmol gminus1) 119899 119877


2

Hg 00224 492815 09604 00311 61463 09064 0000039 1 times 10minus15 09446



a 875 954 plusmn 015



Na2C2O4a 3007 942 plusmn 011







Co2+a 136 991 plusmn 011

Fe3+a 143 970 plusmn 091

Ni2+a 136 991 plusmn 023

V4+a 157 992 plusmn 015

Cu2+a 126 983 plusmn 085





05 1274 plusmn 0082 1002 2769 plusmn 0066 998


05 0882 plusmn 0085 1002 2380 plusmn 0055 999









4 Conclusion





Tap water

V 0 0320 plusmn 0106

2 2315 plusmn 021 998

Co 0 0059 plusmn 0004

2 2041 plusmn 002 991

Ni 0 4392 plusmn 0037

2 6172 plusmn 005 965

Cu 0 0762 plusmn 0137

2 2759 plusmn 032 999

River water

V 0 0606 plusmn 0428

2 2602 plusmn 052 998

Co 0 0041 plusmn 0014

2 2030 plusmn 005 994

Ni 0 2964 plusmn 0377

2 4790 plusmn 052 964












CV-AAS 3ndash7 0015 5 gt150 [19]











Acknowledgment


References










































































020406080

100120

Reco

very

()

Mercury


0times10

2

(a)

Vanadium


020406080

100120

0times10

2

(b)

Cobalt


020406080

100120

0times10

2

(c)

020406080

100120

Reco

very

()

Nickel


0times10

2

(d)

Lead


020406080

100120

0times10

2

(e)

Manganese


020406080

100120

0times10

2

(f)

020406080

100120

0 5 10 15 20

Reco

very

()

Contact time (min)

Cadmium

times102

(g)


Copper

020406080

100120

0times10

2

(h)


Zinc

020406080

100120

times102

(i)





1was







119905versus 119905


119905versus



00 100 200 300 400 500

Time (min)

minus2

minus4

minus6

R2= 09641

log(QeminusQt)

(a)

0400000800000

12000001600000

0 500 1000 1500 2000Time (min)

R2= 1

tQt

(min

gm

moL

minus1)

(b)

000093000095000097000099000101

0 10 20 30 40

t12 (min)

R2= 07665

Qt

(mm

oLg

minus1)

(c)

020406080

100120

0 200 400 600 800

R2= 09604

1Qe

(gm

moL

minus1)



log Qe

minus05

minus1

minus15

minus2

minus25

R2= 09064

log Ce

(e)

0 2000000001205762

R2= 09446

minus124

minus12

minus116

minus112

minus108

minus104

lnQe

(f)





1(minminus1) 119877

2 119876119890



11990512

119870119894

1198772













119889Cu(II) 14548 gt 119870

119889Hg(II) 50 and 120572 lt 1






0

0005

001

0015

002

0025

0 50 100 150


Qe

(mm

oLg

minus1)













1(minminus1) 119877

2 119876119890



11990512

119870119894

1198772

Co 000146 000230 09533 000255 3283 0991 11961 000004 09427V 000007 000299 08843 000390 137896 1 186 0000003 04423Cu 000004 000484 08318 000315 420290 1 076 0000001 06093Zn 000033 000553 09541 000096 41447 09998 2504 0000009 06659Ni 000161 000345 09552 000267 4169 09987 8983 000004 07309Fe 000193 000161 07571 000350 2302 09993 12409 0000008 03698Hg 000024 000668 07452 000100 68596 09998 1452 0000009 04446



2512 048 058 15365 005 002 003 326 4976120572 119870119889Hg119870

119889M+ 198 10287 8599 032 93116 263832 146879 1528 mdash





119877119871=

1

1 + 119870119871119862119894

(13)






119871= 0 the



119871value lt 01








2)2]


2)2




V Cu Ni Co Fe Hg119870119889

27011 159800 12829 35836 5260 52376120572 119870119889Hg119870

119889M+ 1939 03278 40825 1462 9957 mdash




0

20

40

60

80

100

120

0 2 4 6

Reco

very

()




two replicates





0

20

40

60

80

100

120

Reco

very

()

1M H

Cl

1 th

iour

ea

1M H

Cl

2 th

iour

ea

1M H

Cl

3 th

iour

ea

1M H

Cl

4 th

iour

ea

5M H

Cl

5 th

iour

ea

2M H

NO3

4M H

Cl3M

HN

O3


0

20

40

60

80

100

120

2 4 6 8 10

Reco

very

()

Volume eluent (mL)



2)21M HCl +









1377 7998 595 1606 188 1998 24 9998 523



2119870119865(mmol gminus1) 119899 119877


2

Hg 00224 492815 09604 00311 61463 09064 0000039 1 times 10minus15 09446



a 875 954 plusmn 015



Na2C2O4a 3007 942 plusmn 011







Co2+a 136 991 plusmn 011

Fe3+a 143 970 plusmn 091

Ni2+a 136 991 plusmn 023

V4+a 157 992 plusmn 015

Cu2+a 126 983 plusmn 085





05 1274 plusmn 0082 1002 2769 plusmn 0066 998


05 0882 plusmn 0085 1002 2380 plusmn 0055 999









4 Conclusion





Tap water

V 0 0320 plusmn 0106

2 2315 plusmn 021 998

Co 0 0059 plusmn 0004

2 2041 plusmn 002 991

Ni 0 4392 plusmn 0037

2 6172 plusmn 005 965

Cu 0 0762 plusmn 0137

2 2759 plusmn 032 999

River water

V 0 0606 plusmn 0428

2 2602 plusmn 052 998

Co 0 0041 plusmn 0014

2 2030 plusmn 005 994

Ni 0 2964 plusmn 0377

2 4790 plusmn 052 964












CV-AAS 3ndash7 0015 5 gt150 [19]











Acknowledgment


References










































































00 100 200 300 400 500

Time (min)

minus2

minus4

minus6

R2= 09641

log(QeminusQt)

(a)

0400000800000

12000001600000

0 500 1000 1500 2000Time (min)

R2= 1

tQt

(min

gm

moL

minus1)

(b)

000093000095000097000099000101

0 10 20 30 40

t12 (min)

R2= 07665

Qt

(mm

oLg

minus1)

(c)

020406080

100120

0 200 400 600 800

R2= 09604

1Qe

(gm

moL

minus1)



log Qe

minus05

minus1

minus15

minus2

minus25

R2= 09064

log Ce

(e)

0 2000000001205762

R2= 09446

minus124

minus12

minus116

minus112

minus108

minus104

lnQe

(f)





1(minminus1) 119877

2 119876119890



11990512

119870119894

1198772













119889Cu(II) 14548 gt 119870

119889Hg(II) 50 and 120572 lt 1






0

0005

001

0015

002

0025

0 50 100 150


Qe

(mm

oLg

minus1)













1(minminus1) 119877

2 119876119890



11990512

119870119894

1198772

Co 000146 000230 09533 000255 3283 0991 11961 000004 09427V 000007 000299 08843 000390 137896 1 186 0000003 04423Cu 000004 000484 08318 000315 420290 1 076 0000001 06093Zn 000033 000553 09541 000096 41447 09998 2504 0000009 06659Ni 000161 000345 09552 000267 4169 09987 8983 000004 07309Fe 000193 000161 07571 000350 2302 09993 12409 0000008 03698Hg 000024 000668 07452 000100 68596 09998 1452 0000009 04446



2512 048 058 15365 005 002 003 326 4976120572 119870119889Hg119870

119889M+ 198 10287 8599 032 93116 263832 146879 1528 mdash





119877119871=

1

1 + 119870119871119862119894

(13)






119871= 0 the



119871value lt 01








2)2]


2)2




V Cu Ni Co Fe Hg119870119889

27011 159800 12829 35836 5260 52376120572 119870119889Hg119870

119889M+ 1939 03278 40825 1462 9957 mdash




0

20

40

60

80

100

120

0 2 4 6

Reco

very

()




two replicates





0

20

40

60

80

100

120

Reco

very

()

1M H

Cl

1 th

iour

ea

1M H

Cl

2 th

iour

ea

1M H

Cl

3 th

iour

ea

1M H

Cl

4 th

iour

ea

5M H

Cl

5 th

iour

ea

2M H

NO3

4M H

Cl3M

HN

O3


0

20

40

60

80

100

120

2 4 6 8 10

Reco

very

()

Volume eluent (mL)



2)21M HCl +









1377 7998 595 1606 188 1998 24 9998 523



2119870119865(mmol gminus1) 119899 119877


2

Hg 00224 492815 09604 00311 61463 09064 0000039 1 times 10minus15 09446



a 875 954 plusmn 015



Na2C2O4a 3007 942 plusmn 011







Co2+a 136 991 plusmn 011

Fe3+a 143 970 plusmn 091

Ni2+a 136 991 plusmn 023

V4+a 157 992 plusmn 015

Cu2+a 126 983 plusmn 085





05 1274 plusmn 0082 1002 2769 plusmn 0066 998


05 0882 plusmn 0085 1002 2380 plusmn 0055 999









4 Conclusion





Tap water

V 0 0320 plusmn 0106

2 2315 plusmn 021 998

Co 0 0059 plusmn 0004

2 2041 plusmn 002 991

Ni 0 4392 plusmn 0037

2 6172 plusmn 005 965

Cu 0 0762 plusmn 0137

2 2759 plusmn 032 999

River water

V 0 0606 plusmn 0428

2 2602 plusmn 052 998

Co 0 0041 plusmn 0014

2 2030 plusmn 005 994

Ni 0 2964 plusmn 0377

2 4790 plusmn 052 964












CV-AAS 3ndash7 0015 5 gt150 [19]











Acknowledgment


References

















































































119889Cu(II) 14548 gt 119870

119889Hg(II) 50 and 120572 lt 1






0

0005

001

0015

002

0025

0 50 100 150


Qe

(mm

oLg

minus1)













1(minminus1) 119877

2 119876119890



11990512

119870119894

1198772

Co 000146 000230 09533 000255 3283 0991 11961 000004 09427V 000007 000299 08843 000390 137896 1 186 0000003 04423Cu 000004 000484 08318 000315 420290 1 076 0000001 06093Zn 000033 000553 09541 000096 41447 09998 2504 0000009 06659Ni 000161 000345 09552 000267 4169 09987 8983 000004 07309Fe 000193 000161 07571 000350 2302 09993 12409 0000008 03698Hg 000024 000668 07452 000100 68596 09998 1452 0000009 04446



2512 048 058 15365 005 002 003 326 4976120572 119870119889Hg119870

119889M+ 198 10287 8599 032 93116 263832 146879 1528 mdash





119877119871=

1

1 + 119870119871119862119894

(13)






119871= 0 the



119871value lt 01








2)2]


2)2




V Cu Ni Co Fe Hg119870119889

27011 159800 12829 35836 5260 52376120572 119870119889Hg119870

119889M+ 1939 03278 40825 1462 9957 mdash




0

20

40

60

80

100

120

0 2 4 6

Reco

very

()




two replicates





0

20

40

60

80

100

120

Reco

very

()

1M H

Cl

1 th

iour

ea

1M H

Cl

2 th

iour

ea

1M H

Cl

3 th

iour

ea

1M H

Cl

4 th

iour

ea

5M H

Cl

5 th

iour

ea

2M H

NO3

4M H

Cl3M

HN

O3


0

20

40

60

80

100

120

2 4 6 8 10

Reco

very

()

Volume eluent (mL)



2)21M HCl +









1377 7998 595 1606 188 1998 24 9998 523



2119870119865(mmol gminus1) 119899 119877


2

Hg 00224 492815 09604 00311 61463 09064 0000039 1 times 10minus15 09446



a 875 954 plusmn 015



Na2C2O4a 3007 942 plusmn 011







Co2+a 136 991 plusmn 011

Fe3+a 143 970 plusmn 091

Ni2+a 136 991 plusmn 023

V4+a 157 992 plusmn 015

Cu2+a 126 983 plusmn 085





05 1274 plusmn 0082 1002 2769 plusmn 0066 998


05 0882 plusmn 0085 1002 2380 plusmn 0055 999









4 Conclusion





Tap water

V 0 0320 plusmn 0106

2 2315 plusmn 021 998

Co 0 0059 plusmn 0004

2 2041 plusmn 002 991

Ni 0 4392 plusmn 0037

2 6172 plusmn 005 965

Cu 0 0762 plusmn 0137

2 2759 plusmn 032 999

River water

V 0 0606 plusmn 0428

2 2602 plusmn 052 998

Co 0 0041 plusmn 0014

2 2030 plusmn 005 994

Ni 0 2964 plusmn 0377

2 4790 plusmn 052 964












CV-AAS 3ndash7 0015 5 gt150 [19]











Acknowledgment


References












































































1(minminus1) 119877

2 119876119890



11990512

119870119894

1198772

Co 000146 000230 09533 000255 3283 0991 11961 000004 09427V 000007 000299 08843 000390 137896 1 186 0000003 04423Cu 000004 000484 08318 000315 420290 1 076 0000001 06093Zn 000033 000553 09541 000096 41447 09998 2504 0000009 06659Ni 000161 000345 09552 000267 4169 09987 8983 000004 07309Fe 000193 000161 07571 000350 2302 09993 12409 0000008 03698Hg 000024 000668 07452 000100 68596 09998 1452 0000009 04446



2512 048 058 15365 005 002 003 326 4976120572 119870119889Hg119870

119889M+ 198 10287 8599 032 93116 263832 146879 1528 mdash





119877119871=

1

1 + 119870119871119862119894

(13)






119871= 0 the



119871value lt 01








2)2]


2)2




V Cu Ni Co Fe Hg119870119889

27011 159800 12829 35836 5260 52376120572 119870119889Hg119870

119889M+ 1939 03278 40825 1462 9957 mdash




0

20

40

60

80

100

120

0 2 4 6

Reco

very

()




two replicates





0

20

40

60

80

100

120

Reco

very

()

1M H

Cl

1 th

iour

ea

1M H

Cl

2 th

iour

ea

1M H

Cl

3 th

iour

ea

1M H

Cl

4 th

iour

ea

5M H

Cl

5 th

iour

ea

2M H

NO3

4M H

Cl3M

HN

O3


0

20

40

60

80

100

120

2 4 6 8 10

Reco

very

()

Volume eluent (mL)



2)21M HCl +









1377 7998 595 1606 188 1998 24 9998 523



2119870119865(mmol gminus1) 119899 119877


2

Hg 00224 492815 09604 00311 61463 09064 0000039 1 times 10minus15 09446



a 875 954 plusmn 015



Na2C2O4a 3007 942 plusmn 011







Co2+a 136 991 plusmn 011

Fe3+a 143 970 plusmn 091

Ni2+a 136 991 plusmn 023

V4+a 157 992 plusmn 015

Cu2+a 126 983 plusmn 085





05 1274 plusmn 0082 1002 2769 plusmn 0066 998


05 0882 plusmn 0085 1002 2380 plusmn 0055 999









4 Conclusion





Tap water

V 0 0320 plusmn 0106

2 2315 plusmn 021 998

Co 0 0059 plusmn 0004

2 2041 plusmn 002 991

Ni 0 4392 plusmn 0037

2 6172 plusmn 005 965

Cu 0 0762 plusmn 0137

2 2759 plusmn 032 999

River water

V 0 0606 plusmn 0428

2 2602 plusmn 052 998

Co 0 0041 plusmn 0014

2 2030 plusmn 005 994

Ni 0 2964 plusmn 0377

2 4790 plusmn 052 964












CV-AAS 3ndash7 0015 5 gt150 [19]











Acknowledgment


References











































































V Cu Ni Co Fe Hg119870119889

27011 159800 12829 35836 5260 52376120572 119870119889Hg119870

119889M+ 1939 03278 40825 1462 9957 mdash




0

20

40

60

80

100

120

0 2 4 6

Reco

very

()




two replicates





0

20

40

60

80

100

120

Reco

very

()

1M H

Cl

1 th

iour

ea

1M H

Cl

2 th

iour

ea

1M H

Cl

3 th

iour

ea

1M H

Cl

4 th

iour

ea

5M H

Cl

5 th

iour

ea

2M H

NO3

4M H

Cl3M

HN

O3


0

20

40

60

80

100

120

2 4 6 8 10

Reco

very

()

Volume eluent (mL)



2)21M HCl +









1377 7998 595 1606 188 1998 24 9998 523



2119870119865(mmol gminus1) 119899 119877


2

Hg 00224 492815 09604 00311 61463 09064 0000039 1 times 10minus15 09446



a 875 954 plusmn 015



Na2C2O4a 3007 942 plusmn 011







Co2+a 136 991 plusmn 011

Fe3+a 143 970 plusmn 091

Ni2+a 136 991 plusmn 023

V4+a 157 992 plusmn 015

Cu2+a 126 983 plusmn 085





05 1274 plusmn 0082 1002 2769 plusmn 0066 998


05 0882 plusmn 0085 1002 2380 plusmn 0055 999









4 Conclusion





Tap water

V 0 0320 plusmn 0106

2 2315 plusmn 021 998

Co 0 0059 plusmn 0004

2 2041 plusmn 002 991

Ni 0 4392 plusmn 0037

2 6172 plusmn 005 965

Cu 0 0762 plusmn 0137

2 2759 plusmn 032 999

River water

V 0 0606 plusmn 0428

2 2602 plusmn 052 998

Co 0 0041 plusmn 0014

2 2030 plusmn 005 994

Ni 0 2964 plusmn 0377

2 4790 plusmn 052 964












CV-AAS 3ndash7 0015 5 gt150 [19]











Acknowledgment


References












































































1377 7998 595 1606 188 1998 24 9998 523



2119870119865(mmol gminus1) 119899 119877


2

Hg 00224 492815 09604 00311 61463 09064 0000039 1 times 10minus15 09446



a 875 954 plusmn 015



Na2C2O4a 3007 942 plusmn 011







Co2+a 136 991 plusmn 011

Fe3+a 143 970 plusmn 091

Ni2+a 136 991 plusmn 023

V4+a 157 992 plusmn 015

Cu2+a 126 983 plusmn 085





05 1274 plusmn 0082 1002 2769 plusmn 0066 998


05 0882 plusmn 0085 1002 2380 plusmn 0055 999









4 Conclusion





Tap water

V 0 0320 plusmn 0106

2 2315 plusmn 021 998

Co 0 0059 plusmn 0004

2 2041 plusmn 002 991

Ni 0 4392 plusmn 0037

2 6172 plusmn 005 965

Cu 0 0762 plusmn 0137

2 2759 plusmn 032 999

River water

V 0 0606 plusmn 0428

2 2602 plusmn 052 998

Co 0 0041 plusmn 0014

2 2030 plusmn 005 994

Ni 0 2964 plusmn 0377

2 4790 plusmn 052 964












CV-AAS 3ndash7 0015 5 gt150 [19]











Acknowledgment


References












































































Tap water

V 0 0320 plusmn 0106

2 2315 plusmn 021 998

Co 0 0059 plusmn 0004

2 2041 plusmn 002 991

Ni 0 4392 plusmn 0037

2 6172 plusmn 005 965

Cu 0 0762 plusmn 0137

2 2759 plusmn 032 999

River water

V 0 0606 plusmn 0428

2 2602 plusmn 052 998

Co 0 0041 plusmn 0014

2 2030 plusmn 005 994

Ni 0 2964 plusmn 0377

2 4790 plusmn 052 964












CV-AAS 3ndash7 0015 5 gt150 [19]











Acknowledgment


References
















































































Acknowledgment


References









































































solid phase extraction of inorganic mercury using 5 ...€¦ · solid phase extraction of inorganic...

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