research article integrated nanozero valent iron and biosurfactant-aided remediation...

Research ArticleIntegrated Nanozero Valent Iron and Biosurfactant-AidedRemediation of PCB-Contaminated Soil

He Zhang Baiyu Zhang and Bo Liu

Northern Region Persistent Organic Pollution Control (NRPOP) Laboratory Faculty of Engineering and Applied ScienceMemorial University St Johnrsquos NL Canada A1B 3X5

Correspondence should be addressed to Baiyu Zhang bzhangmunca

Received 24 February 2016 Accepted 28 April 2016

Academic Editor Ezio Ranieri

Copyright copy 2016 He Zhang et alThis is an open access article distributed under theCreativeCommonsAttributionLicensewhichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Polychlorobiphenyls (PCBs) have been identified as environmental hazards for years Due to historical issues a considerableamount of PCBs was released deep underground in Canada In this research a nanoscale zero valent iron- (nZVI-) aideddechlorination followed by biosurfactant enhanced soil washing method was developed to remove PCBs from soil During nZVI-aided dechlorination the effects of nZVI dosage initial pH level and temperature were evaluated respectively Five levels of nZVIdosage and two levels of initial pH were experimented to evaluate the PCB dechlorination rate Additionally the temperaturechanges could positively influence the dechlorination process In soil washing the presence of nanoiron particles played a key rolein PCB removal The crude biosurfactant was produced using a bacterial stain isolated from the Atlantic Ocean and was appliedfor soil washing The study has led to a promising technology for PCB-contaminated soil remediation

1 Introduction

As family members of chlorinated hydrocarbons polychlori-nated biphenyls (PCBs) are a group of manmade chemicalswhich were first synthesized in 1881 and commercialized inNorth American industries from the 1930s to the late 1970s[1ndash3] Although never manufactured in Canada PCBs havebeen imported and widely used in hundreds of industrial andcommercial applications (eg electric insulators plasticizersfor adhesives lubricants hydraulic fluids sealants cuttingoils and flame retardants) due to their nonflammability andelectrical insulating properties as well as chemical stability athigh temperature and low vapor pressure [4 5]

These compounds did not exist in nature After synthesisthey were found in the environment in 1966 [6] Since thenPCBs were so widely discovered in the global environmentwhere trace concentrations were detected even in remoteareas such as the atmosphere of the Arctic and the Antarcticand the hydrosphere and biosphere [3]

Exposure to PCBs can lead to cancer and a variety ofserious noncancer health effects on different systems HenceCanada restricted the use of PCBs in 1977 and prohibited the

import of PCBs in 1980 [7 8] Current legislation allows PCB-containing electrical equipment manufactured before 1980 toremain in use until the end of their service life however strictmaintenance and handling procedures and regulatory controlby governments are required to prevent any release into theenvironment [2] As specified in the Federal ContaminatedSites Inventory (FCSI) PCB-contaminated sites are recog-nized in all the provinces and territories throughout CanadaIn fact most of these sites are contaminated as a consequenceof inappropriate handling storage and disposal [4]

Federal and provincial governments as well as associatedindustries have been obliged to endeavour research effortsand provide financial support for site identification reme-diation and long term monitoring Since 1994 the numberof PCB-contaminated sites has been reduced under provin-cial jurisdiction However the large amount of remaininguntreated sites and the revived problems in the treated sitesare still risking the provincial ecosystems and environmentThe preliminary assessment process estimates the volume offree products could be 15ndash20 million litres and the majorityof the PCB pollutants are deep underground [9] Industrieshave beenmaking efforts to solve individual problems andor

Hindawi Publishing CorporationApplied and Environmental Soil ScienceVolume 2016 Article ID 5390808 11 pageshttpdxdoiorg10115520165390808

2 Applied and Environmental Soil Science

processes related to site remediation practices during thepast years Among the existing technologies incineration andlandfill were frequently applied However the remediationwas usually long term and costly and the exhaust couldcause secondary pollution [10]There is a shortage of effectivetechnologies to treat and remove PCB contaminants fromsoils and sedimentsThis situation has hindered the efforts toeffectively protect the environments of this regionThereforeit is desired that innovative technologies that can enhancethe efficiencies and effectiveness of remediation of PCB-contaminated sites be developed within Canadian context

Nanoscale zero valent iron (nZVI) particles have beenwidely applied in removing chloridized hydrocarbons includ-ing PCBs due to their extraordinarily reductive property[11 12] Some recent research has revealed that nZVI particlesare effective in the transformation of a large variety ofenvironmental contaminants while they are inexpensive andnontoxic [13] nZVI may chemically reduce PCBs effectivelythrough reductive dechlorination allowing the pollutant tobe readily biodegradable after treatment Studies by MuellerandNowack [14] have shown that nZVI as a reactive barrier isvery effective in the reduction of chlorinated methane chlo-rinated ethane chlorinated benzenes and other polychlo-rinated hydrocarbons Varma [15] has successfully appliednZVI in soil columns with a wide range of plant phenols asadditives which allows greater access to the contaminant andcreates less hazardous waste in the manufacturing processThe application of nZVI to the contaminated soil couldenhance the dechlorination of PCBs nevertheless higherchlorinated biphenyls require much longer time than lowerones to be completely dechlorinated Biphenyls as the finalproduct of PCBs are still environmental and health hazardswhich need further treatment A time-saving technology thatcan completely degrade PCBs in the soils or remove PCBsfrom the soils is consequently in demand

Soil washing has been applied to effectively and rapidlyremove soil contaminants This technology provides a closedsystem that remains unaffected by external conditions [16]and the system permits the control of the conditions (egadditive concentration) under which the soil particles aretreated [17] Soil washing is cost-effective and often combinedwith other remediation technologies Solvents are critical forsoil washing and selected on the basis of their ability tosolubilize specific contaminants and on their environmentaland health effects [18] However although soil washing canprovide a high efficiency when extracting contaminants fromthe soil there are still some limitations when dealing withPCBs One of the constraints is that PCBs have low watersolubilitymdash00027ndash042 ngL [19] they are soluble in organicor hydrocarbon solvents oils and fats Moreover PCBs tendto stay in the soils instead of flushing with solvents or waterSince high-chlorinated biphenyls are less water-soluble thanlow-chlorinated ones and PCBs often preferentially adhereto the clay or silt fraction of the soils [20] removal of thehigh-chlorinated biphenyls in clayey or silty soils will becomeextremely difficult It is thus very hard to find an appropriatewashing solvent for PCB removal from soil

Biosurfactants are surface-active compounds from bio-logical sources usually extracellular produced by bacteria

yeast or fungi [21] Compared with chemical surfactantsbiosurfactants have been applied in contaminated soil reme-diation due to the advantages of low toxicity high speci-ficity biodegradability and biocompatibility and functional-ity under extreme conditions [22ndash24] Applying biosurfac-tants as the solvents in soil washing systems to treat PCB-contaminated soil has the following benefits (1) it wouldeffectively enhance solubilization of PCBs in the washingsolution leading to increased removal efficiency and (2) itcould stimulate microbial activity that enhances biodegrada-tion of PCBs which are soil bound [24] However althoughthe application of biosurfactants with soil washing can sig-nificantly increase the solubility of PCBs that increase theextraction efficiency [23] PCBs that dissolved in the washingsolution need to be further treated before being released intothe environment As persistent organic pollutants PCBs arehard to degrade leading to costly and complex posttreatmentprocesses before discharge [24] In addition larger volumesof washing solution may be needed when additives like bio-surfactants are used A high biosurfactant concentration inthe washing solution can cause foaming problems and inhi-bit the ability to remove PCBs from the soil [25] Increasingattention has been received on the combination of differenttechnologies in recent years These technologies can beapplied in sequence to enhance the cost effectiveness [26]Effective dechlorination approaches which can be integratedwith soil washing and facilitate PCB biodegradation are thusdesired

This study is essential for the applications to the removalof PCBs from soil It aims to combine nanotechnology and anexisting soil washing system with biosurfactants as the sol-vent to better clean up the PCB-contaminated sites Sincehigher chlorinated biphenyls have lower aqueous solubilitiesthan lower chlorinated ones biosurfactant-aided soil washingcould have higher removal efficiencies on lower chlorinatedbiphenyls than that on higher ones [27] Therefore thesequence of the combined technologies would be betterstarted with nZVI-aided dechlorination and followed bybiosurfactant-aided soil washing Through the experimentalstudy of various factors (one factor at a time) affecting PCBdechlorination (nZVI dosage pH and temperature) and soilwashing effectiveness (nZVI and concentrations of biosur-factant solution) the research output is expected to generateenvironmentally friendly and economicallytechnically feasi-ble solutions for helping solve the challenging site contamina-tion problem in Canada

2 Materials and Methods

21 Materials Thematerials were as follows

(1) Soil soil used in this research was fine sands pur-chased from a local company City SandampGravel LtdSt Johnrsquos NL

(2) PCBs commercial PCB products are no longer man-ufactured and traded in Canada The contaminantsused in this study were in the form of transformeroil obtained from local industry The overall PCB

Applied and Environmental Soil Science 3

concentration in the transformer oil was measured tobe 120 ppm by a commercial lab

(3) nZVI particles nanofer star one kind of commer-cialized air-stable nanoiron powders was purchasedfrom NANO IRON sro Czech Republic

(4) Biosurfactants a Bacillus sp bacterial strain isolatedfrom the Atlantic Ocean [28] was cultured to generatebiosurfactants in theNRPOPLab After culturing andextraction the crude biosurfactants were separatedfrom the media and characterized through testingthe criticalmicelle concentration (CMC)These crudebiosurfactants were then ready for use

(5) Other materials and chemicals anhydrous sodiumsulfate (ACS reagent) hexane (CHROMASOLVPlus for HPLC ge 95) acetone (CHROMASOLVPlus for HPLC ge999) Supelclean Sulfoxide SPETube (PE frit bed wt 3 g volume 6mL) biphenyl-d

10

(99 atom D) EPA 525 5251 PCB Mix (500120583gmL each component in hexane analytical standard)barium chloride dihydrate (BaCl

2sdot2H2O ACS

reagent ge990) magnesium sulfate heptahydrate(MgSO

4sdot7H2O ReagentPlus ge990) sulfuric acid

concentrate (01M H2SO4in water (02N)) chloro-

form (CHROMASOLV Plus for HPLC ge999)methanol (CHROMASOLV for HPLC ge999)ammonium sulfate ((NH

4)2SO4 ReagentPlus

ge990) sodium chloride (NaCl BioXtra ge995(AT)) iron(II) sulfate heptahydrate (FeSO

4sdot7H2O

BioReagent ge99) monopotassium phosphate(KH2PO4 ge99) dipotassium hydrogenphosphate

(K2HPO4 ge99) sucrose (BioXtra ge995)

select yeast extract zinc sulfate heptahydrate(ZnSO

4sdot7H2O BioReagent) manganese(II) sulfate

tetrahydrate (MnSO4sdot4H2O BioReagent) Boric acid

(H3BO3 BioReagent ge995) Copper(II) sulfate

pentahydrate (CuSO4sdot5H2O BioReagent ge98)

sodium molybdate dihydrate (Na2MoO4sdot2H2O ACS

reagent ge99) cobalt(II) chloride hexahydrate(CoCl

2sdot6H2O BioReagent) EDTA (ethylenedi-

aminetetraacetic acid ACS reagent ge 99) nickel(II)chloride hexahydrate (NiCl

2sdot6H2O BioReagent) and

potassium iodide (KI BioXtra ge990) all of themwere purchased from Sigma-Aldrich Canada CoON Canada

22 Methods

221 nZVI-Aided PCB Dechlorination

(1) PCB-Contaminated Soil Preparation The synthesized soilthat contaminated by transformer oil was applied to simulatePCB-contaminated oil spills such as uncontrolled wastedisposals or leakage of storage tanks The soil was driedat room temperature for one week and passed through a2mm stainless steel sieve to remove any coarse sand andgravel particles as well as to improve the homogeneitybefore use Then soil characterization was conducted Aftercharacterization PCB-contaminated soil was prepared in two

20 L-stainless steel trays Each tray was filled with 10 kg ofsoil and 2 L of transformer oil The soil and oil were mixedthoroughly until it reached a homogenous phase The trayswere then covered with tin foil and stored for one week Afterthat the oil in the tray was drained off until there was no fluidin soil and the soil was ready for nZVI treatment

(2) Air-Stable nZVI Powder Activation Before any experi-ment the surface character and crystal structure of thesecommercial nZVI particles were examined by scanningelectron microscopy (SEM) and X-ray Diffraction (XRD)respectively in the Core Research Equipment amp InstrumentTraining Lab (CREAIT) at Memorial University For theactivation the air-stable nanopowder of nZVI was mixedwith deionized water at a ratio of 1 4 The mixture was thenactivated by a Branson Sonifier S-450D digital ultrasonichomogenizer for 2mins at 50 amplitude The treated mix-ture was sealed and stored at room temperature for two daysbefore dechlorination experiments

(3) Dechlorination Activated nZVI slurry was transferredinto a 500mL wide neck amber glass bottle with 200 g PCB-contaminated soil and 30mL deionized water was addedas well The solid and liquid phases were thoroughly mixedand each bottle was covered with a solid-top cap Thehomogenous mixture was then stored at room temperatureand let the reaction between nZVI particles and PCBs lastfor 75 days The effects of the nZVI dosage (5 75 10 125and 15 g per kg PCB-contaminated soil) initial pH (2 5)and temperatures (0∘C 35∘C and 100∘C) were investigatedrespectively

222 Biosurfactant-Aided Soil Washing

(1) Batch-Scale Washing System Design and Setup The exper-imental setup used to perform soil washing experimentsconsists of a washing fluid reservoir a soil column a peri-staltic pump and an effluent collection system (Figure 1)Theperistaltic pump contains variable speed drives that can runfrom 04 to 850mLmin The soil column is made of glass toavoid any interference from phthalate esters when contactingwith plastic materials and with a cylindrically diameter of19mm and 15 cm in length The column was packed with25 g of nZVI-treated soil and the outlet end of the columnwas fitted with glass beads and glass wool to prevent soil lossduring washing The system assembly is shown in Figure 1

(2) Biosurfactant Production and Washing Fluid PreparationThe bacteria used to generate biosurfactant were isolatedfrom the Atlantic Ocean recently Till now no commer-cial biosurfactant products associated with this strain wereavailable Thus biosurfactants need to be produced beforeconducting washing experiments For the media and cul-tivation conditions a medium modified from Peng et al[29] was used which contains the following composition(gL) sucrose (10) KH

2PO4(34) K

2HPO4(44) (NH

4)2SO4

(100) FeSO4sdot7H2O (28 times 10minus4) NaCl (22) MgSO

4sdot7H2O

(102) yeast extract (05) and 05mLof trace element solutionincluding (gL) ZnSO

4sdot7H2O (232) MnSO

4sdot4H2O (178)


Figure 1 Sketch of soil washing system assembly

H3BO3(056) CuSO

4sdot5H2O (10) Na

2MoO4sdot2H2O (039)

CoCl2sdot6H2O (042) EDTA (10) NiCl

2sdot6H2O (0004) and

KI (066) Cultivations were performed in 1 L Erlenmeyerflasks containing 750mL medium at 30∘C and stirred ina rotary shaker for 7 days Enriched culture medium after7 days was centrifuged at 10000 rpm for 10min and thesupernatant layer was extracted using chloroform-methanol(1 2) on a magnetic stirrer for 8 hours The solvent layerwas separated from the aqueous phase and the solvent wasremoved by rotary evaporation at 40∘C and 60 rpm underreduced pressure The CMC of the resulting crude biosurfac-tants was determined through measuring the surface tensionin accordance with ASTM D1331-14 method The surfacetension of a crude biosurfactant solution was measured byusing Du Nouy Tensiometer The CMC value of the crudebiosurfactants was estimated by the surface tension curveover a wide concentration range They were determinedby noting the concentrations at which the surface tensionreaches the minimum

(3) Soil Washing Parallel experiments were conducted toinvestigate the effect of nanoiron particles on soil washingtreatment Both of the PCB-contaminated soil samplestreated with 75 gkg and without nZVI particles were loadedinto the washing columns respectively to test whether thepresence of nanoparticles would have any effect on soilwashing Twenty-five grams of the soil was washed withdeionized water in a down flowmode for 15 hours at a steadyflow rate controlled by the peristaltic pump To investigatethe effect of crude biosurfactant the soil samples werewashed with the crude biosurfactant solution (025 05and 3 vv) in a down flow mode for 3 hours at a steady flowrate controlled by the peristaltic pumpThe washing effluents

were sampled at 0 10 20 30 60 90 120 and 180 minutes ofwashing to investigate the change of PCB concentration withtime The change of PCB concentration in soil was deter-mined by measuring the soil sample before and after wash-ing

223 Sample Analysis The PCBs in each soil sample werefirst extracted into the solvent phase according to EPAmethod 3550B ultrasonic extraction A modification of themethod was conducted to achieve a better testing perfor-mance Two grams of soil sample was transferred to a 30mLbeaker Two grams of anhydrous sodium sulfate was added tothe sample and the solution was well mixed Two surrogates500120583L 10 ppm biphenyl-d

10and 200 120583L 10 ppm EPA 525

5251 PCB Mix were spiked to the sample A hexane solventof 93mL was immediately added to the matrix in orderto bring the final volume to 100mL This was followed bydisrupting the sample with a Branson Sonifier ultrasonicprobe for 2 minutes at 50 amplitude After ultrasonicextraction 1mL extract was filtered by glass wool and readyfor solid phase extraction (SPE) cleanup Supelclean SulfoxideSPE cartridges purchased from Sigma-Aldrich were usedfor transformer oil cleanup The SPE normal procedure ofconditioning loading washing and elution was followedThe conditioning was accomplished by eluting 10mL ofacetone to remove residual moisture from the SupelcleanSulfoxide cartridges This was followed by adding 20mL ofn-hexane to equilibrate the cartridges The pretreated 1mLsamplewas loaded onto the cartridge andwashedwith 55mLof n-hexane Elution was done with 13mL of n-hexane Theeluate was concentrated to 1mL by gentle air blow Thecleanup extracts were transferred into GC vials ready for ana-lysis

The PCB concentration in liquid phase was analyzedusing modified Liquid-Liquid Microextraction (LLME) [30]followed by the GC-MS analysis For modified LLME 25 120583Lof 10 ppm biphenyl-d

10and 10 120583L of 10 ppm EPA 525 5251

PCB Mix were spiked as surrogates to each 10mL watersample (25 ngL biphenyl-d

10and 10 ngL EPA 525 5251

PCB Mix aqueous solution) which was treated by vortexmixing for 10 sec This was followed by adding 500 120583L ofhexane and the vortexmixing for 1minThewater samplewasthen centrifuged at 4000 rpm for 5min Ten 120583L of extractwas transferred to Microvials for GC analysis Instrumentalanalysis was performed using an Agilent 7890A5975C gaschromatographndashmass spectrometer (GC-MS) equipped withan Agilent 7693 autosampler GC conditions were set upbased on EPA method 8082A A few adjustments were madeto ensure that no PCB congener was retained in the col-umn

Total ion current (TIC) chromatogram was acquired toexamine the changes of PCBs in soil samples The analysisof each congener and its surrogate was carried out inselected-ion monitoring (SIM) chromatogram The ratio ofsample congener response to standard congener responsewas defined as the relative concentration which was used inthe results and discussion All the samples were treated andanalyzed in duplicate


Table 1 Soil properties

Properties ResultsSoil pH 753Bulk density 178 gcm3

Particle density 271 gcm3

Pore space 343Moisture content 0069Cation exchange capacity 9522 cmolkgHydraulic conductivity 0024 cms

Table 2 Soil particle size distribution determined by sieve analysis

Particle Diameter (mm) Size distribution ()Gravel gt20 45Sand 005ndash20 925Silt 0002ndash005 25Clay lt0002 05

3 Results and Discussion


311 Soil Characterization Before the nZVI-aided PCBdechlorination experiments basic soil properties includingparticle size distribution soil pH bulk density particledensity pore space cation exchange capacity hydraulic con-ductivity and moisture content of the purchased plain soilwere measured The results are shown in Tables 1 and 2The plain soil used in this research was mainly composedof sand which was suitable for soil washing The bulkdensity particle density pore space hydraulic conductivityand moisture content are physical properties which canbe greatly influenced by soil composition and particle sizedistribution The pH of the soil was slight alkalinity whichcould result in a higher cation exchange capacity (CEC) valueIn an environmental context CEC stands for the ability of soilto adsorb contaminants The pH and CEC are two importantchemical properties which could affect the soil remediationprocess and thus need to be examined before remediation

Metal substances of the plain soil sample were charac-terized by ICP-MS Table 3 displays the analytical resultsIt is noticed that a high concentration of iron was presentwhich was of 336 g per kg soil The addition of nZVI forPCB dechlorination thus would not much influence thecomposition of soil

312 Analysis of PCB Concentrations in the Original SpikedSoil The concentrations of PCBs in the spiked soil samplewere evaluated before conducting the dechlorination and soilwashing experiments Four PCB congeners were selected asanalytes due to their high abundances in the transformeroil namely Penta-178 Penta-187 Penta-200 and Hexa-208The former parts of the names represent the numbers ofchlorine atoms in the congener compounds while the latterones are their corresponding retention times (minutes) in the

Table 3Metal substances in the soil sample determined by ICP-MS

Metals Concentration in soil (mgkg)Arsenic 5306Barium 643918Cadmium 0146Chromium 16815Copper 13727Iron 33562114Lead 17681Mercury ltLDLNickel 9142Selenium ltLDLThallium 0444Uranium 1675Vanadium 46084Zinc 71958Note LDL = lower detection limit

4 6 8 10 12 14 16 18 20 22 24 26 28 300

500100015002000250030003500400045005000

121110

9

87

6

1

5

4

13

2

Resp

onse

Time (min)

1

Figure 2 GC-MS SIM spectra of PCBs in contaminated soilsample spiked with bipenyl-d

10and EPA 5255251 PCBs standard

(1) Biphenyl-d10 (2) 221015840441015840-Tetrachlorobiphenyl (3) 2210158403101584046-

Pentachlorobiphenyl (4) Biphenyl (5) Tetra-156 (6) Tetra-163 (7)Penta-178 (8) Penta-187 (9) Penta-200 (10) Hexa-208 (11) Hexa-218 (12) Hexa-228

Table 4 The initial relative concentrations of PCBs in the spikedsoil

Analytes Surrogate Response ratioPenta-178 2210158403101584046-Pentachlorobiphenyl 0384Penta-187 2210158403101584046-Pentachlorobiphenyl 0551Penta-200 2210158403101584046-Pentachlorobiphenyl 0736Hexa-208 2210158403101584046-Pentachlorobiphenyl 0262

MS spectra (Figure 2)The average response ratios of PCBs totheir corresponding surrogates are listed in Table 4

313 nZVI Characterization and Activation ThecommercialnZVI particles were characterized by SEM and XRD priorto their applications in PCB dechlorination in soil Figure 3shows the SEM image of nZVI particles It can be seen that


Figure 3 SEM Image of the commercial nZVI particles

10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

0

250

500

750

1000

Inte

nsity

(cou

nts)

Fe

Fe3O4 Fe3O4

Diffraction angle 2120579 (∘)

Figure 4 XRD of the nZVI particle

the majority of the particles were nearly spherical in shapeand uniform in size The particle size was in the range of 20ndash100 nm with an average particle size of 50 nm

Figure 4 displays the XRD pattern of the nZVI particlesand it proved that there were crystal iron particles existedin the commercial product The 2120579 values of the peaks werecompared with the standard data for iron and its oxides suchas magnetite and 120572-Fe Apparent peak at the 2120579 of 449∘indicates the presence of 120572-Fe while other apparent peaksshow the presence of iron oxides The redox potential ofnZVI slurry was decreased from 360mV tominus300mV after theactivation

314 Natural Attenuation of PCBs The changes of PCBconcentrations in the contaminated soil were tracked on the1st 15th and 45th day respectively during the natural atten-uation process As depicted in Figure 5 the concentrations ofall the four congeners did not change significantly within the45-day period It illustrated that the dechlorination rates ofPCBs during the natural attenuation process were extremelyslow It also proved that the PCBswere not able to be degradedwithout any additional treatment

315 Effect of nZVIDosage Theperformance of PCBdechlo-rination using different nZVI dosages is shown in Figure 6

Penta-178 Penta-187 Penta-200 Hexa-2080

20

40

60

80

100

Relat

ive c

once

ntra

tion

()

Day 1Day 15Day 45

Figure 5 Natural attenuation of PCBs in contaminated soil

50 75 100 125 150 175minus10

minus5

0

5

10

15

20

25

30

35

40

Dec

hlor

inat

ion

rate

()

Dosage (gkg soil)

Penta-178Penta-187

Penta-200Hexa-208

Figure 6 Effect of nZVI dosage on PCB dechlorination in thecontaminated soil

The trends of the PCBdechlorination rate versus nZVIdosagewere similar based on the results of all the four congenersThe overall PCB dechlorination rate was first increased asnZVI dosage increased from 5 to 75 gkg indicating that theincrease of nZVI dosage can accelerate the dechlorinationof PCBs The overall dechlorination rate of PCBs was thendecreased when the nZVI dosage increased higher than75 gkg The maximum dechlorination rates of Penta-178Penta-187 Penta-200 and Hexa-208 during 75 days periodwere 363 203 189 and 329 respectivelyThe resultsindicated that when choosing 75 gkg as the nZVI dosagethe highest dechlorination rates were achieved in all fourcongeners Addingmore nZVI particles had shown a negative



25

50

75

100

125

Dec

hlor

inat

ion

rate

()

pH-2pH-5

Figure 7 Effect of pH on PCB dechlorination in the contaminatedsoil

influence on PCB dechlorination This was possibly due tothe particle aggregation formed during mixing [31] Besidesthe nZVI aggregation the biotransformation from higherchlorinated biphenyls to lower ones may also affect the PCBdechlorination rate under multiple nZVI dosages Based onthe experimental results the nZVI dosage of 75 gkg with thebest PCB dechlorination performance was selected for thefollowing treatments

316 Effect of pH Level Two levels of pH were selectedto evaluate the effect of pH on PCB dechlorination Theresult is shown in Figure 7 After 75 days monitoring theaverage dechlorination rates of Penta-178 Penta-187 Penta-200 and Hexa-208 at pH of 2 were 108 89 50 and56 respectively while their average dechlorination ratesat pH of 5 were 119 118 68 and 62 respectivelyThe dechlorination rates of each PCB congener were higherat pH of 5 than those at pH of 2 Previous studies haveshown that an acid environment with more protons couldaccelerate the PCB dechlorination [32] The results of thisstudy led to a different conclusion It might be because inthis case the protons were sufficient at pH of 5 so thatpH was not a dominating factor on PCB dechlorinationanymore In addition the addition of H

2SO4would have

more interference with the mass transfer of PCBs from thesoil to the iron (Fe) surface [32]The pHof 5 was thus selectedto be the initial pH condition in the following experiments

317 Effect of Temperature The effect of temperature on PCBdechlorination after 75 days was investigated with resultsshown in Figure 8 The PCB dechlorination was greatlyenhanced when the temperature increased from 0 to 100∘CAs the temperature increased the PCB dechlorination ofPenta-178 improved the most with a rate change from 101to 342 The dechlorination rates of Penta-187 Penta-200and Hexa-208 were enhanced from 113 to 322 from

0 20 40 60 80 1005

10

15

20

25

30

35

40

Dec

hlor

inat

ion

rate

()

Penta-178Penta-187

Penta-200Hexa-208

Temperature (∘C)

Figure 8 Effect of temperature on nZVI-aided PCB dechlorination


101520253035404550556065

PCB

rem

oval

rate

()

Non-nZVI-treated soilnZVI-treated soil

Figure 9 Effect of the nZVI particles on PCB removal during soilwashing

98 to 294 and from 137 to 288 respectively Theseresults showed that a temperature increasewould enhance themobility of PCBs from the soil to the iron surfaces and thusaccelerate the dechlorination reaction [32]


321 Effect of nZVI Particles on Soil Washing The effect ofthe nZVI particles on PCB removal during the soil washingtreatment was investigated Figure 9 showed the resultsAlthough the insolubility of PCBs makes their distributionnegligible in water phase the PCBs in the transformer oilcould be flushed out of the column due to the high flow rateduring direct soil washing without using any biosurfactants


000 002 004 006 008 01025

30

35

40

45

50

55

60Su

rface

tens

ion

(mN

m)

Concentration of crude biosurfactant ()

CMC

Figure 10 CMC of the crude biosurfactant

As shown in Figure 9 after 15 hours of operation about 18to 30 of PCBs in the congeners were removed by directwashing of the non-nZVI-treated soil

After the nZVI-aided dechlorination a red color wasobserved in the treated soil implying the formation offerric hydroxides or ferric oxides It indicated that the nZVIparticles were transferred to their oxidative forms after thereaction During washing of the nZVI-treated soil the PCBconcentration of each congener was significantly decreasedIn Figure 9 the removal rates of PCBs after washing werebetween 60 and 62 in the nZVI-treated soil It wasillustrated that the treatment by the nZVI particles greatlyenhanced the soil washing efficiency Besides the presenceof nanoscale ferric oxides in the system plays a key role inPCB removal [33] The contaminated soil trapped a certainamount of transformer oil and the oil droplets were blockedby the pore throat of soil due to the high interfacial tensionbetween oil and soil [34] With the presence of nanoscaleferric oxides the interfacial tensionwould be reduced and themobility of oil droplets would be increased [33] As a resultmore oil droplets were desorbed from the soil resulting inan increased effectiveness of soil washing This experimentconfirmed that the combination of the nZVI-aided dechlori-nation and soil washing is reasonable and feasible

322 CMC of the Crude Biosurfactant The surface tension ofa series of biosurfactant solutions with different biosurfactantconcentrations was tracked The trend of surface tensionversus biosurfactant concentration was shown in Figure 10The value of surface tension was decreased sharply till thebiosurfactant concentration reached 001 When the bio-surfactant concentration was higher than 001 the surfacetension changes became relatively stableTherefore the CMCof the crude biosurfactant was determined to be 001

323 Effect of Biosurfactant Concentration on Soil WashingThe nZVI-treated soil sample was washed by crude biosur-facant solutions The concentration of crude biosurfactantin the washing fluid was set as 3 05 and 025 Theinitial flow rate of the column washing fluid was set within

the range of 18ndash20mLmin The results of relative PCBconcentrations (the ratio of sample congener response tostandard congener response) in column effluent were shownin Figures 11(a)ndash11(c) The elution of PCBs started at 10minThe PCB concentrations in effluents were sharply increasedand reached their peaks at 15ndash45min Steep declines werefollowed by the peaks and the gentle deduction appeared inthe final stage

The overall PCB removal rates after washing of the nZVI-treated soil were examined As shown in Figure 12 the higherthe concentration of the crude biosurfactant solution usedthe higher the removal rate achievedThemaximum removalratewas foundwhenusing 3crude biosurfactant and 90ofthe total four PCB congeners were removed from the soilThefinal removal rates using 05 and 025 crude biosurfactantsolutions were 80 and 75 respectively The PCB removalrates using all the three crude biosurfactant solution werehigher than 75 indicating the promising effectiveness ofbiosurfactant-aided soil washing

The decreasing of washing flow rates occurred especiallywith higher biosurfactant dosesWhen supplying thewashingfluid with the 3 crude biosurfactant a backwashing stepwas requiredwithin 30ndash60minwashing time It was observedthat the bounce of PCBs at 60min in Figure 11(a) was becauseof backwash The most possible explanation is that the crudebiosurfactant contained insoluble particulate matter couldblock the pathway of washing flow thus reducing bothflow rate and emulsification rate It could further lead toa longer treatment period Results indicated that the crudebiosurfactant solution with a concentration of 05 couldremove the majority of the four PCB congeners with theshortest treatment time (within 60 minutes) Therefore 05was selected as an appropriate biosurfactant concentrationfor further applications

The SIM spectrum shows the removal of almost all thePCBs in the soil sample after washing As shown in Figure 13the peaks of PCBs had almost disappeared after washingwith 05 crude biosurfactant solution only the peaks ofsurrogates were left Besides the contents of the transformeroil that generated the baseline wander were also removed Asa consequence the crude biosurfactant solution was able toremove almost all the organic components including PCBsin transformer oil unselectively

4 Conclusions

This research has focused on the development of a two-step treatment consisting of nZVI-aided dechlorination fol-lowed by biosurfactant-based soil washing technology toremove PCBs from soil In nZVI-aided dechlorination theeffects of nZVI dosage initial pH and temperature on PCBtransformation were evaluated one at a time respectivelyThe selected dosage of nZVI was 75 gkg soil Addingmore nZVI particles could have negative influence on PCBdechlorination since the aggregates could be easily formed asthe nZVI dosage increases An environment with pH lowerthan 5 did not much influence the removal rates of PCBsindicating the presence of sufficient protons in the systemThe results showed that the lower pH would actually inhibit


0 30 60 90 120 150 1800

20

40

60

80

100

120

140Re

lativ

e PCB

conc

entr

atio

n (

)

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(a)

0 30 60 90 120 150 1800

20

40

60

80

100

120

140

Relat

ive P

CB co

ncen

trat

ion

()

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(b)

0 30 60 90 120 150 1800

10

20

30

40

50

60

70

Relat

ive P

CB co

ncen

trat

ion

()

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(c)

Figure 11 Relative concentrations of PCBs in washing effluent with (a) 3 (b) 05 and (c) 025 crude biosurfactant solution

the dechlorination by the presence of H2SO4 which has an

effect on the reduction of mass transfer An improvement ofdechlorination was observed as the temperature increasedsince higher temperature would accelerate the dechlorinationreaction

In the soil washing system the presence of nZVI particlesplays a key role in PCB removal They can greatly enhancethe soil washing efficiency because the interfacial tensionbetween the oil phase and the soil phase would be reducedand the mobility of oil droplets would be increased Soilwashing of nZVI remediated soil can be enhanced by biosur-factant Higher biosurfactant concentration could increasethe solubilization of PCBs from soil phase to liquid phaseTheoverall PCB removal rates using all the three crude biosurfac-tant concentrations (3 05 and 025) were 90 80

and 75 respectively indicating the promising effectivenessof this biosurfactant Compared with the 3 biosurfactantsolution the crude biosurfactant concentrations of 05 and025weremore cost-effectiveThe 05 crude biosurfactantsolution could remove the majority of PCBs within a shortertime than the solution with a concentration of 025 There-fore 05 was recommended as an appropriate biosurfactantconcentration for future applicationThis study shows a greatpotential in developing a promising treatment technology forPCB-contaminated soil remediation Pilot-scale applicationswill be carried out to demonstrate the technology transfer

Competing Interests

The authors declare that they have no competing interests



10

20

30

40

50

60

70

80

90

PCB

rem

oval

rate

()

305025

Figure 12 The washing efficiencies of PCBs in the nZVI-treatedcontaminated soil by different concentrations of crude biosurfactantsolution

5 10 15 20 25 30

5 10 15 20 25 30

After washing

0500

10001500200025003000

Resp

onse

0500

10001500200025003000

Resp

onse

Retention time (min)


Before washing

Figure 13 GC-MS SIM spectra of PCBs in the contaminated soilbefore and after washing by 05 crude biosurfactant solution

Acknowledgments

The authors would like to express gratitude to The Natu-ral Sciences and Engineering Research Council of Canada(NSERC) and the Canada Foundation for Innovation (CFI)for their support

References

[1] D Pal J BWeber andM R Overcash ldquoFate of polychlorinatedbiphenyls (PCBs) in soil-plant systemsrdquo in Residue Reviews pp45ndash98 Springer New York NY USA 1980

[2] Canadian Council of Resource and Environment Ministers(CCREM)The PCB Story (CCREM) Toronto Canada 1986

[3] S Tanabe ldquoPCB problems in the future foresight from currentknowledgerdquo Environmental Pollution vol 50 no 1 pp 5ndash281988

[4] Canadian Council of Ministers of the Environment (CCME)ldquoCanadian soil quality guidelines for the protection of environ-mental and human health polychlorinated biphenyls (total)rdquo inCanadian Environmental Quality Guidelines Canadian Councilof Ministers of the Environment Winnipeg Canada 1999

[5] US Environmental Protection Agency PCBs in the UnitedStates industrial use and environmental distribution p 24 1976httpnepisepagovExeZyPDFcgi2000I275PDFDockey=2000I275PDF

[6] S Jensen ldquoReport of a new chemical hazardrdquoNew Scientist vol32 no 612 p 445 1966

[7] W M J Strachan ldquoPolychlorinated biphenyls (PCBs) fate andeffects in the Canadian environmentrdquo EPS Report 4HA2Environment Canada 1988

[8] L A Barrie D Gregor B Hargrave et al ldquoArctic contaminantssources occurrence and pathwaysrdquo Science of The Total Envi-ronment vol 122 no 1-2 pp 1ndash74 1992

[9] AMEC Earth and Environmental Ltd Commission 881 Envi-ronmental Site Investigation B371 CHPP Tanks Prepared forDefence Construction Canada Goose Bay Canada 2008

[10] Federal Contaminated Sites Portal Federal Contaminated SitesAction Plan (FCSAP) February 2014 httpwwwfederal-contaminatedsitesgccadefaultasplang=en

[11] A Mikszewski Emerging Technologies for the in Situe Remedia-tion of PCB-contaminated Soils and Sediments Bioremediationand Nanoscale Zerovalent Iron US Environmental ProtectionAgency 2004

[12] SM CookAssessing theUse andApplication of Zero-Valent IronNanoparticle Technology for Remediation at Contaminated SitesJackson State University 2009

[13] W-X Zhang ldquoNanoscale iron particles for environmentalremediation an overviewrdquo Journal of Nanoparticle Research vol5 no 3-4 pp 323ndash332 2003

[14] N C Mueller and B Nowack ldquoNanoparticles for remediationsolving big problems with little particlesrdquo Elements vol 6 no6 pp 395ndash400 2010

[15] RVarma ldquoGreener synthesis of noblemetal nanostructures andnanocompositesrdquo in Presented at the US EPA Science ForumInnovative TechnologiesmdashKey to Environmental and EconomicProgress Washington DC USA 2008

[16] W Chu and K H Chan ldquoThe mechanism of the surfactant-aided soil washing system for hydrophobic and partial hydro-phobic organicsrdquo Science of The Total Environment vol 307 no1ndash3 pp 83ndash92 2003

[17] K Urum T Pekdemir and M Gopur ldquoOptimum conditionsfor washing of crude oil-contaminated soil with biosurfactantsolutionsrdquo Process Safety and Environmental Protection vol 81no 3 pp 203ndash209 2003

[18] D Feng L Lorenzen C Aldrich and PWMare ldquoEx situ dieselcontaminated soil washingwithmechanical methodsrdquoMineralsEngineering vol 14 no 9 pp 1093ndash1100 2001

[19] H I Gomes C Dias-Ferreira L M Ottosen and A B RibeiroldquoElectrodialytic remediation of polychlorinated biphenyls con-taminated soil with iron nanoparticles and two different sur-factantsrdquo Journal of Colloid and Interface Science vol 433 pp189ndash195 2014

[20] T Lyons D W Grosse and R A Parker EPA engineeringissue technology alternatives for the remediation of PCB


contaminated soils and sediments (No EPA600S-13079)Washington DC USA 2013

[21] B Zhang G H Huang and B Chen ldquoEnhanced bioremedi-ation of petroleum contaminated soils through cold-adaptedbacteriardquo Petroleum Science and Technology vol 26 no 7-8 pp955ndash971 2008

[22] X Qin B Chen G Huang and B Zhang ldquoA relation-analysis-based approach for assessing risks of petroleum-contaminatedsites in Western Canadardquo New Developments in SustainablePetroleum Engineering vol 1 no 2 pp 183ndash200 2009

[23] P F Amaral M A Z Coelho I M Marrucho and J ACoutinho ldquoBiosurfactants from yeasts characteristics produc-tion and applicationrdquo in Biosurfactants pp 236ndash249 SpringerNew York NY USA 2010

[24] H Xia and Z Yan ldquoEffects of biosurfactant on the remediationof contaminated soilsrdquo in Proceedings of the 4th Interna-tional Conference on Bioinformatics and Biomedical Engineering(iCBBE rsquo10) pp 1ndash4 IEEE Chengdu China June 2010

[25] Unified Facilities Guide Specifications (USGS) Soil Washingthrough SeparationSolubilizationUFGS-02 54 23 2010 httpswwwwbdgorgccbDODUFGSUFGS200220542023pdf

[26] H I Gomes C Dias-Ferreira and A B Ribeiro ldquoOverviewof in situ and ex situ remediation technologies for PCB-contaminated soils and sediments and obstacles for full-scaleapplicationrdquo Science of the Total Environment vol 445-446 pp237ndash260 2013

[27] W Y Shiu and D Mackay ldquoA critical review of aqueous solubil-ities vapor pressures Henryrsquos law constants and octanolndashwaterpartition coefficients of the polychlorinated biphenylsrdquo Journalof Physical and Chemical Reference Data vol 15 no 2 pp 911ndash929 1986

[28] Q Cai B Zhang B Chen Z Zhu W Lin and T Cao ldquoScreen-ing of biosurfactant producers from petroleum hydrocarboncontaminated sources in cold marine environmentsrdquo MarinePollution Bulletin vol 86 no 1-2 pp 402ndash410 2014

[29] F Peng Z Liu L Wang and Z Shao ldquoAn oil-degradingbacterium Rhodococcus erythropolis strain 3C-9 and its biosur-factantsrdquo Journal of Applied Microbiology vol 102 no 6 pp1603ndash1611 2007

[30] J S Zheng B Liu J Ping B Chen H J Wu and B YZhang ldquoVortex- and shaker-assisted liquidndashliquidmicroextrac-tion (VSA-LLME) coupled with gas chromatography and massspectrometry (GC-MS) for analysis of 16 polycyclic aromatichydrocarbons (PAHs) in offshore produced waterrdquo Water Airand Soil Pollution vol 226 no 9 pp 318ndash331 2015

[31] N C Muller and B Nowack ldquoNano zero valent ironmdashthe solu-tion for water and soil remediationrdquo Report of the ObservatoryNANO 2010

[32] P Varanasi A Fullana and S Sidhu ldquoRemediation of PCBcontaminated soils using iron nano-particlesrdquo Chemospherevol 66 no 6 pp 1031ndash1038 2007

[33] L Hendraningrat and O Torsaeligter ldquoMetal oxide-based nano-particles revealing their potential to enhance oil recovery indifferent wettability systemsrdquo Applied Nanoscience vol 5 no 2pp 181ndash199 2015

[34] A Roustaei S Saffarzadeh and M Mohammadi ldquoAn evalu-ation of modified silica nanoparticlesrsquo efficiency in enhancingoil recovery of light and intermediate oil reservoirsrdquo EgyptianJournal of Petroleum vol 22 no 3 pp 427ndash433 2013

Submit your manuscripts athttpwwwhindawicom

Forestry ResearchInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Environmental and Public Health

Journal of



EcosystemsJournal of


MeteorologyAdvances in

EcologyInternational Journal of


Marine BiologyJournal of


Hindawi Publishing Corporationhttpwwwhindawicom

Applied ampEnvironmentalSoil Science

Volume 2014

Advances in


Environmental Chemistry

Atmospheric SciencesInternational Journal of



Waste ManagementJournal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal of

Geophysics


Geological ResearchJournal of

EarthquakesJournal of


BiodiversityInternational Journal of


ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

OceanographyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of Computational Environmental SciencesHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


ClimatologyJournal of


processes related to site remediation practices during thepast years Among the existing technologies incineration andlandfill were frequently applied However the remediationwas usually long term and costly and the exhaust couldcause secondary pollution [10]There is a shortage of effectivetechnologies to treat and remove PCB contaminants fromsoils and sedimentsThis situation has hindered the efforts toeffectively protect the environments of this regionThereforeit is desired that innovative technologies that can enhancethe efficiencies and effectiveness of remediation of PCB-contaminated sites be developed within Canadian context

Nanoscale zero valent iron (nZVI) particles have beenwidely applied in removing chloridized hydrocarbons includ-ing PCBs due to their extraordinarily reductive property[11 12] Some recent research has revealed that nZVI particlesare effective in the transformation of a large variety ofenvironmental contaminants while they are inexpensive andnontoxic [13] nZVI may chemically reduce PCBs effectivelythrough reductive dechlorination allowing the pollutant tobe readily biodegradable after treatment Studies by MuellerandNowack [14] have shown that nZVI as a reactive barrier isvery effective in the reduction of chlorinated methane chlo-rinated ethane chlorinated benzenes and other polychlo-rinated hydrocarbons Varma [15] has successfully appliednZVI in soil columns with a wide range of plant phenols asadditives which allows greater access to the contaminant andcreates less hazardous waste in the manufacturing processThe application of nZVI to the contaminated soil couldenhance the dechlorination of PCBs nevertheless higherchlorinated biphenyls require much longer time than lowerones to be completely dechlorinated Biphenyls as the finalproduct of PCBs are still environmental and health hazardswhich need further treatment A time-saving technology thatcan completely degrade PCBs in the soils or remove PCBsfrom the soils is consequently in demand

Soil washing has been applied to effectively and rapidlyremove soil contaminants This technology provides a closedsystem that remains unaffected by external conditions [16]and the system permits the control of the conditions (egadditive concentration) under which the soil particles aretreated [17] Soil washing is cost-effective and often combinedwith other remediation technologies Solvents are critical forsoil washing and selected on the basis of their ability tosolubilize specific contaminants and on their environmentaland health effects [18] However although soil washing canprovide a high efficiency when extracting contaminants fromthe soil there are still some limitations when dealing withPCBs One of the constraints is that PCBs have low watersolubilitymdash00027ndash042 ngL [19] they are soluble in organicor hydrocarbon solvents oils and fats Moreover PCBs tendto stay in the soils instead of flushing with solvents or waterSince high-chlorinated biphenyls are less water-soluble thanlow-chlorinated ones and PCBs often preferentially adhereto the clay or silt fraction of the soils [20] removal of thehigh-chlorinated biphenyls in clayey or silty soils will becomeextremely difficult It is thus very hard to find an appropriatewashing solvent for PCB removal from soil

Biosurfactants are surface-active compounds from bio-logical sources usually extracellular produced by bacteria

yeast or fungi [21] Compared with chemical surfactantsbiosurfactants have been applied in contaminated soil reme-diation due to the advantages of low toxicity high speci-ficity biodegradability and biocompatibility and functional-ity under extreme conditions [22ndash24] Applying biosurfac-tants as the solvents in soil washing systems to treat PCB-contaminated soil has the following benefits (1) it wouldeffectively enhance solubilization of PCBs in the washingsolution leading to increased removal efficiency and (2) itcould stimulate microbial activity that enhances biodegrada-tion of PCBs which are soil bound [24] However althoughthe application of biosurfactants with soil washing can sig-nificantly increase the solubility of PCBs that increase theextraction efficiency [23] PCBs that dissolved in the washingsolution need to be further treated before being released intothe environment As persistent organic pollutants PCBs arehard to degrade leading to costly and complex posttreatmentprocesses before discharge [24] In addition larger volumesof washing solution may be needed when additives like bio-surfactants are used A high biosurfactant concentration inthe washing solution can cause foaming problems and inhi-bit the ability to remove PCBs from the soil [25] Increasingattention has been received on the combination of differenttechnologies in recent years These technologies can beapplied in sequence to enhance the cost effectiveness [26]Effective dechlorination approaches which can be integratedwith soil washing and facilitate PCB biodegradation are thusdesired

This study is essential for the applications to the removalof PCBs from soil It aims to combine nanotechnology and anexisting soil washing system with biosurfactants as the sol-vent to better clean up the PCB-contaminated sites Sincehigher chlorinated biphenyls have lower aqueous solubilitiesthan lower chlorinated ones biosurfactant-aided soil washingcould have higher removal efficiencies on lower chlorinatedbiphenyls than that on higher ones [27] Therefore thesequence of the combined technologies would be betterstarted with nZVI-aided dechlorination and followed bybiosurfactant-aided soil washing Through the experimentalstudy of various factors (one factor at a time) affecting PCBdechlorination (nZVI dosage pH and temperature) and soilwashing effectiveness (nZVI and concentrations of biosur-factant solution) the research output is expected to generateenvironmentally friendly and economicallytechnically feasi-ble solutions for helping solve the challenging site contamina-tion problem in Canada

2 Materials and Methods

21 Materials Thematerials were as follows

(1) Soil soil used in this research was fine sands pur-chased from a local company City SandampGravel LtdSt Johnrsquos NL

(2) PCBs commercial PCB products are no longer man-ufactured and traded in Canada The contaminantsused in this study were in the form of transformeroil obtained from local industry The overall PCB






10


2sdot2H2O ACS





4)2SO4 ReagentPlus


4sdot7H2O














22 Methods









2PO4(34) K

2HPO4(44) (NH

4)2SO4


4sdot7H2O



4sdot4H2O (178)



H3BO3(056) CuSO

4sdot5H2O (10) Na

2MoO4sdot2H2O (039)







10and 200 120583L 10 ppm EPA 525



10and 10 120583L of 10 ppm EPA 525 5251


10and 10 ngL EPA 525 5251

















4 6 8 10 12 14 16 18 20 22 24 26 28 300

500100015002000250030003500400045005000

121110

9

87

6

1

5

4

13

2

Resp

onse

Time (min)

1











10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

0

250

500

750

1000

Inte

nsity

(cou

nts)

Fe

Fe3O4 Fe3O4








20

40

60

80

100

Relat

ive c

once

ntra

tion

()

Day 1Day 15Day 45


50 75 100 125 150 175minus10

minus5

0

5

10

15

20

25

30

35

40

Dec

hlor

inat

ion

rate

()

Dosage (gkg soil)

Penta-178Penta-187

Penta-200Hexa-208





25

50

75

100

125

Dec

hlor

inat

ion

rate

()

pH-2pH-5




2SO4would have



0 20 40 60 80 1005

10

15

20

25

30

35

40

Dec

hlor

inat

ion

rate

()

Penta-178Penta-187

Penta-200Hexa-208

Temperature (∘C)



101520253035404550556065

PCB

rem

oval

rate

()







000 002 004 006 008 01025

30

35

40

45

50

55

60Su

rface

tens

ion

(mN

m)


CMC










4 Conclusions



0 30 60 90 120 150 1800

20

40

60

80

100

120

140Re

lativ

e PCB

conc

entr

atio

n (

)

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(a)

0 30 60 90 120 150 1800

20

40

60

80

100

120

140

Relat

ive P

CB co

ncen

trat

ion

()

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(b)

0 30 60 90 120 150 1800

10

20

30

40

50

60

70

Relat

ive P

CB co

ncen

trat

ion

()

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(c)






Competing Interests




10

20

30

40

50

60

70

80

90

PCB

rem

oval

rate

()

305025


5 10 15 20 25 30

5 10 15 20 25 30

After washing

0500

10001500200025003000

Resp

onse

0500

10001500200025003000

Resp

onse



Before washing


Acknowledgments


References









































Journal of












Volume 2014

Advances in









Geophysics



















10


2sdot2H2O ACS





4)2SO4 ReagentPlus


4sdot7H2O














22 Methods









2PO4(34) K

2HPO4(44) (NH

4)2SO4


4sdot7H2O



4sdot4H2O (178)



H3BO3(056) CuSO

4sdot5H2O (10) Na

2MoO4sdot2H2O (039)







10and 200 120583L 10 ppm EPA 525



10and 10 120583L of 10 ppm EPA 525 5251


10and 10 ngL EPA 525 5251

















4 6 8 10 12 14 16 18 20 22 24 26 28 300

500100015002000250030003500400045005000

121110

9

87

6

1

5

4

13

2

Resp

onse

Time (min)

1











10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

0

250

500

750

1000

Inte

nsity

(cou

nts)

Fe

Fe3O4 Fe3O4








20

40

60

80

100

Relat

ive c

once

ntra

tion

()

Day 1Day 15Day 45


50 75 100 125 150 175minus10

minus5

0

5

10

15

20

25

30

35

40

Dec

hlor

inat

ion

rate

()

Dosage (gkg soil)

Penta-178Penta-187

Penta-200Hexa-208





25

50

75

100

125

Dec

hlor

inat

ion

rate

()

pH-2pH-5




2SO4would have



0 20 40 60 80 1005

10

15

20

25

30

35

40

Dec

hlor

inat

ion

rate

()

Penta-178Penta-187

Penta-200Hexa-208

Temperature (∘C)



101520253035404550556065

PCB

rem

oval

rate

()







000 002 004 006 008 01025

30

35

40

45

50

55

60Su

rface

tens

ion

(mN

m)


CMC










4 Conclusions



0 30 60 90 120 150 1800

20

40

60

80

100

120

140Re

lativ

e PCB

conc

entr

atio

n (

)

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(a)

0 30 60 90 120 150 1800

20

40

60

80

100

120

140

Relat

ive P

CB co

ncen

trat

ion

()

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(b)

0 30 60 90 120 150 1800

10

20

30

40

50

60

70

Relat

ive P

CB co

ncen

trat

ion

()

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(c)






Competing Interests




10

20

30

40

50

60

70

80

90

PCB

rem

oval

rate

()

305025


5 10 15 20 25 30

5 10 15 20 25 30

After washing

0500

10001500200025003000

Resp

onse

0500

10001500200025003000

Resp

onse



Before washing


Acknowledgments


References









































Journal of












Volume 2014

Advances in









Geophysics
















H3BO3(056) CuSO

4sdot5H2O (10) Na

2MoO4sdot2H2O (039)







10and 200 120583L 10 ppm EPA 525



10and 10 120583L of 10 ppm EPA 525 5251


10and 10 ngL EPA 525 5251

















4 6 8 10 12 14 16 18 20 22 24 26 28 300

500100015002000250030003500400045005000

121110

9

87

6

1

5

4

13

2

Resp

onse

Time (min)

1











10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

0

250

500

750

1000

Inte

nsity

(cou

nts)

Fe

Fe3O4 Fe3O4








20

40

60

80

100

Relat

ive c

once

ntra

tion

()

Day 1Day 15Day 45


50 75 100 125 150 175minus10

minus5

0

5

10

15

20

25

30

35

40

Dec

hlor

inat

ion

rate

()

Dosage (gkg soil)

Penta-178Penta-187

Penta-200Hexa-208





25

50

75

100

125

Dec

hlor

inat

ion

rate

()

pH-2pH-5




2SO4would have



0 20 40 60 80 1005

10

15

20

25

30

35

40

Dec

hlor

inat

ion

rate

()

Penta-178Penta-187

Penta-200Hexa-208

Temperature (∘C)



101520253035404550556065

PCB

rem

oval

rate

()







000 002 004 006 008 01025

30

35

40

45

50

55

60Su

rface

tens

ion

(mN

m)


CMC










4 Conclusions



0 30 60 90 120 150 1800

20

40

60

80

100

120

140Re

lativ

e PCB

conc

entr

atio

n (

)

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(a)

0 30 60 90 120 150 1800

20

40

60

80

100

120

140

Relat

ive P

CB co

ncen

trat

ion

()

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(b)

0 30 60 90 120 150 1800

10

20

30

40

50

60

70

Relat

ive P

CB co

ncen

trat

ion

()

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(c)






Competing Interests




10

20

30

40

50

60

70

80

90

PCB

rem

oval

rate

()

305025


5 10 15 20 25 30

5 10 15 20 25 30

After washing

0500

10001500200025003000

Resp

onse

0500

10001500200025003000

Resp

onse



Before washing


Acknowledgments


References









































Journal of












Volume 2014

Advances in









Geophysics




























4 6 8 10 12 14 16 18 20 22 24 26 28 300

500100015002000250030003500400045005000

121110

9

87

6

1

5

4

13

2

Resp

onse

Time (min)

1











10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

0

250

500

750

1000

Inte

nsity

(cou

nts)

Fe

Fe3O4 Fe3O4








20

40

60

80

100

Relat

ive c

once

ntra

tion

()

Day 1Day 15Day 45


50 75 100 125 150 175minus10

minus5

0

5

10

15

20

25

30

35

40

Dec

hlor

inat

ion

rate

()

Dosage (gkg soil)

Penta-178Penta-187

Penta-200Hexa-208





25

50

75

100

125

Dec

hlor

inat

ion

rate

()

pH-2pH-5




2SO4would have



0 20 40 60 80 1005

10

15

20

25

30

35

40

Dec

hlor

inat

ion

rate

()

Penta-178Penta-187

Penta-200Hexa-208

Temperature (∘C)



101520253035404550556065

PCB

rem

oval

rate

()







000 002 004 006 008 01025

30

35

40

45

50

55

60Su

rface

tens

ion

(mN

m)


CMC










4 Conclusions



0 30 60 90 120 150 1800

20

40

60

80

100

120

140Re

lativ

e PCB

conc

entr

atio

n (

)

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(a)

0 30 60 90 120 150 1800

20

40

60

80

100

120

140

Relat

ive P

CB co

ncen

trat

ion

()

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(b)

0 30 60 90 120 150 1800

10

20

30

40

50

60

70

Relat

ive P

CB co

ncen

trat

ion

()

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(c)






Competing Interests




10

20

30

40

50

60

70

80

90

PCB

rem

oval

rate

()

305025


5 10 15 20 25 30

5 10 15 20 25 30

After washing

0500

10001500200025003000

Resp

onse

0500

10001500200025003000

Resp

onse



Before washing


Acknowledgments


References









































Journal of












Volume 2014

Advances in









Geophysics
















10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

0

250

500

750

1000

Inte

nsity

(cou

nts)

Fe

Fe3O4 Fe3O4








20

40

60

80

100

Relat

ive c

once

ntra

tion

()

Day 1Day 15Day 45


50 75 100 125 150 175minus10

minus5

0

5

10

15

20

25

30

35

40

Dec

hlor

inat

ion

rate

()

Dosage (gkg soil)

Penta-178Penta-187

Penta-200Hexa-208





25

50

75

100

125

Dec

hlor

inat

ion

rate

()

pH-2pH-5




2SO4would have



0 20 40 60 80 1005

10

15

20

25

30

35

40

Dec

hlor

inat

ion

rate

()

Penta-178Penta-187

Penta-200Hexa-208

Temperature (∘C)



101520253035404550556065

PCB

rem

oval

rate

()







000 002 004 006 008 01025

30

35

40

45

50

55

60Su

rface

tens

ion

(mN

m)


CMC










4 Conclusions



0 30 60 90 120 150 1800

20

40

60

80

100

120

140Re

lativ

e PCB

conc

entr

atio

n (

)

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(a)

0 30 60 90 120 150 1800

20

40

60

80

100

120

140

Relat

ive P

CB co

ncen

trat

ion

()

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(b)

0 30 60 90 120 150 1800

10

20

30

40

50

60

70

Relat

ive P

CB co

ncen

trat

ion

()

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(c)






Competing Interests




10

20

30

40

50

60

70

80

90

PCB

rem

oval

rate

()

305025


5 10 15 20 25 30

5 10 15 20 25 30

After washing

0500

10001500200025003000

Resp

onse

0500

10001500200025003000

Resp

onse



Before washing


Acknowledgments


References









































Journal of












Volume 2014

Advances in









Geophysics
















25

50

75

100

125

Dec

hlor

inat

ion

rate

()

pH-2pH-5




2SO4would have



0 20 40 60 80 1005

10

15

20

25

30

35

40

Dec

hlor

inat

ion

rate

()

Penta-178Penta-187

Penta-200Hexa-208

Temperature (∘C)



101520253035404550556065

PCB

rem

oval

rate

()







000 002 004 006 008 01025

30

35

40

45

50

55

60Su

rface

tens

ion

(mN

m)


CMC










4 Conclusions



0 30 60 90 120 150 1800

20

40

60

80

100

120

140Re

lativ

e PCB

conc

entr

atio

n (

)

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(a)

0 30 60 90 120 150 1800

20

40

60

80

100

120

140

Relat

ive P

CB co

ncen

trat

ion

()

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(b)

0 30 60 90 120 150 1800

10

20

30

40

50

60

70

Relat

ive P

CB co

ncen

trat

ion

()

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(c)






Competing Interests




10

20

30

40

50

60

70

80

90

PCB

rem

oval

rate

()

305025


5 10 15 20 25 30

5 10 15 20 25 30

After washing

0500

10001500200025003000

Resp

onse

0500

10001500200025003000

Resp

onse



Before washing


Acknowledgments


References









































Journal of












Volume 2014

Advances in









Geophysics















000 002 004 006 008 01025

30

35

40

45

50

55

60Su

rface

tens

ion

(mN

m)


CMC










4 Conclusions



0 30 60 90 120 150 1800

20

40

60

80

100

120

140Re

lativ

e PCB

conc

entr

atio

n (

)

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(a)

0 30 60 90 120 150 1800

20

40

60

80

100

120

140

Relat

ive P

CB co

ncen

trat

ion

()

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(b)

0 30 60 90 120 150 1800

10

20

30

40

50

60

70

Relat

ive P

CB co

ncen

trat

ion

()

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(c)






Competing Interests




10

20

30

40

50

60

70

80

90

PCB

rem

oval

rate

()

305025


5 10 15 20 25 30

5 10 15 20 25 30

After washing

0500

10001500200025003000

Resp

onse

0500

10001500200025003000

Resp

onse



Before washing


Acknowledgments


References









































Journal of












Volume 2014

Advances in









Geophysics















0 30 60 90 120 150 1800

20

40

60

80

100

120

140Re

lativ

e PCB

conc

entr

atio

n (

)

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(a)

0 30 60 90 120 150 1800

20

40

60

80

100

120

140

Relat

ive P

CB co

ncen

trat

ion

()

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(b)

0 30 60 90 120 150 1800

10

20

30

40

50

60

70

Relat

ive P

CB co

ncen

trat

ion

()

Time (min)

Penta-178Penta-187

Penta-200Hexa-208

(c)






Competing Interests




10

20

30

40

50

60

70

80

90

PCB

rem

oval

rate

()

305025


5 10 15 20 25 30

5 10 15 20 25 30

After washing

0500

10001500200025003000

Resp

onse

0500

10001500200025003000

Resp

onse



Before washing


Acknowledgments


References









































Journal of












Volume 2014

Advances in









Geophysics
















10

20

30

40

50

60

70

80

90

PCB

rem

oval

rate

()

305025


5 10 15 20 25 30

5 10 15 20 25 30

After washing

0500

10001500200025003000

Resp

onse

0500

10001500200025003000

Resp

onse



Before washing


Acknowledgments


References









































Journal of












Volume 2014

Advances in









Geophysics


































Journal of












Volume 2014

Advances in









Geophysics














research article integrated nanozero valent iron and biosurfactant-aided remediation...

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