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Fengeta1./dZhejiangUnivSciA20089(~:1283-1287

    ;JournalofZhejiangUniversitySCIENCEA

    ;ISSN1673-565X(Print);ISSN1862-1775(Online)

    ;www.zju.educn0zus;wwwspringerlink.com

    ;E-mail:jZUS@zjueduon

    ;1283

    ;Removalofcopperionsfromelectroplatingrinsewater

    ;usingelectr0dei0niZati0n

    ;XiaoFENG,JunsongGAO.Zu-chengwU,.

    ;(DepartmentofEnvironmentalEngineering,ZhejiangUniversity,Hangzhou310027,China)

    ;(StateKeyLaboratoryofCleanEnergyUtilization,ZhejiangUniversity,Hangzhou310027,China)

    ;(MOEKeyLaboratoryofPollutedEnvironmentRemediationandEcologicalHealth,ZhejiangUniversity,Hangzhou310027,China)

    ;E-mail:wuzc@zju.edu.cn

    ;ReceivedMar.6,2008;revisionacceptedJune2,2008

    ;Abstract:Animprovedconfigurationofthemembranestackwasadoptedintheelectrodeionization(EDI)celltopreventpre.

    ;cipitationofbivalentmetalhydroxideduringtherunning.Theoperationalparametersthatinfluencedtheremovalofcopperions

    ;fromthedilutesolutionwereoptimized.TheresultshowedthatamoderatedecreaseintheinletpHvalueandamoderateincrease

    ;intheappliedvoltagecouldachieveabetterremovaleffect.Thesteadyprocessofelectroplatingwastewatertreatmentcouldbe

    ;achievedwitharemovalefficiencyofmorethan99.5%andanenrichmentfactorof5

    14.Theconcentrationofcopperinpurified

    ;waterwas1essthan0.23mg/L.Thisdemonstratedtheapplicabilityofrecoveringheavymetalionsandpurifiedwaterfromelec.

    ;troplatingemuentforindustrialreuse.

    ;Keywords:Electrodeionization(EDI),Electroplatingwastewater,Heavymetal,Precipitation

    ;doi:10.1631/jzus.A0820166Documentcode:ACLCnumber:X703.1

    ;INTRODUCTION

    ;Electroplatingrinsewaterisoneofthemajor

    ;contributorstoheavymetalpollutioninsurfacewa

    ;ters.Treatmentandremovalofheavymetalshave

    ;receivedconsiderableattentionbecauseoftheirtox

    ;icityandassociationwithvarioushealthproblems

    ;(Jfittnereta1.,2000;JanssenandKoene,2002). ;Copper,wellverifiedinmammalsforitsroleincar

    ;cinogenicity,isbeingwidelyusedinelectroplating ;industries.Asonly30%40%ofallmetalsusedinthe

    ;electroplatingprocessareeffectivelyutilized,the ;wasteemuentsareresponsibleforthesupplyof ;heavymetalpollutantstotheenvironment.Therefore, ;importanceshouldbeattachedtohowtoeffectively ;removemetalionsinelectroplatingwastewater.,vith ;thisaiminmindvariousphyrsicochemicaltreatment ;lCorrespondingauthor

    ;Project(No.Z505060)suppoaedbytheNaturalScienceFoundation ;ofZhejiangProvince,China

    ;methodshavebeenemployed.

    ;Ionexchangehasbeenwidelyappliedforthe

    ;removalofheavymetalionsfromelectroplatingef- ;fluentbecauseitiseffectiveandeasytooperate. ;However,ionexchangeresinsmustberegeneratedby ;additivechemicalreagents(acidandalkali)when ;theyaresaturatedandthiscausesserioussecondary ;pollution.Asanalternativetechnique,electrodialysis ;isnoteconomicalfortreatingdilutesolutionbecause ;ofitshighelectricalresistanceandthedevelopment ;ofconcentrationpolarizationphenomena(Korngold ;f,..1998).

    ;ElectrodeionizationfEDI1isahybridsystem ;combiningionexchangewithelectrodialysiswhichis ;obtainedbyintroducingionexchangeresinsinto ;electrodialysischambers.Thecombinationallowsthe ;treatmentofverydilutesolution(Souilaheta1.,2004), ;andionexchangeresinsinsidearecontinuouslyre. ;generatedelectrochemicallybyhydrogenandhy

    ;droxideionsproducedbywaterelectrolysisoccurring ;inthetwoexternalelectrodecompartmentsrMonzie ;

    ;1284Fengetal/JZh~iangUnivSciA20089(9):12831287

    ;a1..2005).Therefore.EDIhasbeencommercially ;usedfortheproductionofdeionizedwaterinindus

    ;triessuchasmicrOelectrOnics.powergenerationand ;pharmaceuticals.

    ;However,applicationoftheEDIprocessinthe ;fieldofwastewatertreatmentisstillattheresearch ;stage,andpreviousEDIstackconfigurations(Gre

    ;benyuketa1.,1998;KoeneandJanssen,2001:Spoor

    ;Pfa1..2002a;2002b;2002c;2002d;Dzyazkoand ;Belyakov,2004)cannotavoidtheprecipitationof ;bivalentmetalhydroxideasaresultofmetalionre

    ;actingwithhydroxideionpresentintheEDIstack. ;Consequently,theapplicationofEDIinwastewater ;treatmenthasbeengreatlylimitedbythisdrawback. ;AnimprovedconfigurationoftheEDImem

    ;branestackthatavoidsnickelhydroxideprecipitation ;hasbeenpreviouslyreported(Chenandwu.2005). ;Tofurtherexaminetheeffectivenessoftheconfigu

    ;rationandoptimizeoperationalparametersfortesting ;applicabiliwefocusedonrecoveringcopperions ;fromelectroplatingrinsewateraswellasfrompuri

    ;fledwaterforreuseinanEDIoperationintheelec

    ;troplatingindustry.

    ;MATERIALSANDMETH0DS

    ;Ionexchangeresinsandionexchangemembranes

    divinvlbenzene ;TheD00lstronglyacidstyrene

    ;cationexchangeresin(CER)andD20lstronglyalkali ;styrenedivinvlbenzeneanionexchangeresin(AER) ;(HangzhouResinCo.,China),aswellasthepoly

    ;ethyleneheterogeneouscationexchangemembrane ;(CEM1andpolyethyleneheterogeneousanionex

    ;changemembrane(AEM)(Lin’anterTreatment

    ;EquipmentCo.,China)wereused.Characteristicsof ;theresinsandmembranesarelistedinTable1. ;Priortouse.themembraneswereimmersedin ;deionizedwaterfor3dandtheresinswerepretreated ;withthefollowingprocedurestoremoveany ;contamination:

    ;f11ImmersionofCERandAERrespectivelyin ;tworesinvolumesofdeionizedwaterfor24h. ;f21ImmersionofCERintworesinvolumesof ;1.0mol/LNaOHsolutionandAERintworesin ;volumesOf1.0mol/LHClsolutionfor8h.respec

    ;tively,andrinsingindeionizedwateruntiltheemu

    ;entswerepHneutra1.

    ;f31ImmersionofCERintworesinvolumesof ;1.0mol/LHClsolutionandAERintworesinvol

    ;umesof1.0mol/LNaOHsolutionfor8h.respec

    ;tively,andrinsingindeionizedwateruntiltheemu

    ;entswerepHneutra1.

    ;Experimentalset.up

    ;Fig.1showsthattheexperimentalsetuDcon

;sistedoffiveseparatecompartments:anodecom

    ;partment,CERloadedcompartment,concentrate

    ;compartment,AERloadedcompartmentandcathode

    ;compartment.Thecompartmentswereseparatedfrom ;oneanotherbyfourmembranes,andtheeffectivearea ;ofeachmembranewas38.8cmz.TheCERloaded

    ;compartmentwasseparatedfromtheanodecom

    ;partmentandtheconcentratecompartmentbytwo ;CEMs.andtheAERloadedcompartmentwassepa

    ;ratedfromtheconcentratecompartmentandthe ;cathodecompartmentbytwoAEMs.Thetwoouter ;electrodecompartmentshaddimensionsOf19.4 ;cmx2.0cmX1.4cmandeachcontainedaTisubstrate ;RuO,(Tiu021netelectrodewitheffectiveareaof ;38.8cm.TheCERloadedcompartment.thecon

    ;centratecompartmentandtheAER..1oadedcom.. ;partmenthadthesamedimensionsOfl9.4cmx2.0 ;cmx0.7cm.OBethousandmldeionizedwaterwas

    ;circulatedthroughtheconcentratecompartmentand ;500mlofelectrodesolutionsthroughtheanodeand ;cathodecompartments,respectively,byusingthree ;AP1200pumps.Wastewaterwasfedintumthrough ;theCER..1oadedcompartmentandtheAER..1oaded ;compartment.Aregulateddirectcurrent(DC)power ;Table1Characteristicsoftheionexchangeresinsandionexchangemembranes

    ;Note:CER:cationexchangeresin;AER:anionexchangeresin;CEM:cationexchangeme

    mbrane;AEM:anionexchangemembrane

    ;

    ;Fengeta1./JZhejiangUnivSciA20089f9J:12831287

    ;1:Anodecompartment;2:CERloadedcompartment;3:Concen

    ;tratecompartment;4:AERloadedcompartment;5:Cathode ;compartment;6:CEM;7:AEM;8:Electrodesolutionreservoir; ;9:Concentratedsolutionreservoir;1O:Wastewaterreservoir;11:

    ;Purifiedwaterreservoir;12:Pump;13:Valve;14:Flowmeter ;Fig.1Schematicdiagramoftheexperimentalsetup

    ;f0rwastewatertreatment

    ;supply(WYL1701,China)wasusedtoprovidea ;steadyvoltage.

    ;f_,terpurification

    ;TheCERloadedcompartmentwasfilledwith

    ;30mlpretreatedCER.andinadditionthe

    ;AERloadedcompartmentwaspackedwith30ml ;pretreatedAER.The0.05g/LNa2SOdsolutionwas ;circulatedthroughtheanodeandcathodecompart

    ;ments,respectively.Theappliedvoltagewassetatthe ;desiredvalues(20,30and40respectively).Cop

    ;per-containingsimulatedelectroplatingwastewaterof ;50mg/LCuwascontinuouslytreatedwithaflow ;rateOf3L/h.AtintervalOf1h.theCuzconcentra

    ;tionsofboththeconcentratedsolutionandthepuri

    ;fledwaterweredetermined,andthePHvalueofthe ;concentratedsolutionwasmeasured.

     ;Copperionsweredeterminedbytheatomicab;sorptionspectrophotometrymethod.ThePHvalue ;wasmeasuredwithaMeRlerToledo320SPHmeter.

    ;RESUISANDDISCUSSION

    ;EffectofinletpHvalueoncopperenrichmentand ;waterpurification

    ;Thesolubilityproductconstant(Ks)ofCu(OH)2

    ;at1825.Cis2.2x10”.ConcentrationofCuinthe

    ;targetwaterwas50mg/L.WhenthepHvalueofthe ;targetwaterwashigherthan5.72,precipitationof ;Cu(OH)2wouldform.Thereforethetargetwaterwas ;adiustedwitI11.0mol/LH2SO4solutionatpH5.23, ;pH4.28andPH3.22.respectively.Enrichmentof ;copperionswithrespecttotherunningtimeata ;1285

    ;constanteellvoltageof30VfordifferentinletpH ;valuesisshowninFig.2a.FromFig.2aitcanbeseen ;thattheenrichmenteffectwasintheorder:pH ;4.28>1~IH3.22>pH5.23.Arelativelyhighorlow:pH ;valuecausedwaterdissociation,andresinelectro

    ;regenerationandcorrespondingremovalotcopper ;ionswererestrained.ThiswasmanifestedbyCu ;concentrationinthepurifiedwaterafter8h.i…e0.06

    ;mg/LforinletpHvalueof4.28.0.17mg/LforpH ;3.22and0.23mg/LforPH5.23.

    ;Effectofappliedvoltageoncopperenrichment ;andwaterpurification

    ;Theamountofcoppertransportedintothecon

    ;centratecompartmentwithrelativetotime.withthe ;sameinletPHvalueof4.28atdirentapplied ;voltages.isillustratedinFig.2b.Fig.2bshowsthatthe ;Cuconcentrationintheconcentratedsolutionob

    ;viouslyincreasedasthecellvoltagerosefrom20Vto ;30Vor40VWhentheappliedvoltagewasrespec

    ;tively20.30and40VthecorrespondingCucon

    ;centrationinthepurifiedWaterafter8hwas0.19.

;0.06and0.02mg/L.respectively.Highappliedvolt

    ;agewasbeneficialtocopperionsenrichmentand ;remova1.However,thehigherpotentialmade ;400

    ;350

    ;300

    ;250

    ;2o0

    ;l5O

    ;lo0

    ;50

    ;0

    ;8o0

    ;700

    ;600

    ;500

    ;400

    ;3o0

    ;2o0

    ;lo0

    ;O

    ;Ol23456789

    ;Time(h)

    ;Fig.2Copperionconcentrationoftheconcentrated ;solutionat(a)differentinletpHvalueand(b)different ;appHedvoltages

    ;1,gd01重口譬0ud0一矗0u,Hgd0目扫口昌0ud0一矗0u

    ;

    ;1286Fengeta1./JZhejiangUnivSciA20089f9J:12831287

    ;excessiveHandOt-Ygeneratedfromtheelectrode ;reactionsalsomigratetotheconcentratecompartment, ;andthiscausedadecreaseincurrentefficiency. ;Therefore,anappropriateappliedvoltageshouldbe ;chosenforabetterenrichmenteffect,beUerremoval ;effectandlowerenergyconsumption.

    ;Metalhydroxideprecipitation

    ;Accordingtothesolubilityproductprinciple,if ;theionproduct(Qc)oftwokindsofions,forinstance, ;A’andB,

    ;isgreaterthanKspofthecompoundAB,

    ;theprecipitationofABwillform,orelsenoprecipi. ;tationofABforms.KsDofCu(OH)2atl8-25.Cis ;2.2×l0”.pofCuandOHisequalto

    ;Cu1.[OH].

    ;Figs.3aand3brepresentthepHvalueofthe ;concentratedsolutionwithrelativetotimeforthe ;sameexperimentsrepresentedinFigs.2aand2b. ;respectively.BycombiningFigs.2aand2bwith ;Figs.3aand3b,wecalculatedandobtained-lgpof ;Cuzand0H.aslistedinTable2.Fromthetableit ;canbeseenthatlgQcwasconsistentlygreaterthan ;

    ;lgKspofCu(OH)2,i.e.,OcwasfarlessthanKsp,and ;therewasnoprecipitationofCu(OH)2thatformed ;duringthewholeprocessofwaterpurification. ;IntheEDIcel1.whenDCisapplied.thefo1. ;1owingreactionsEq.(1)andEq.(2)mayoccurinthe ;anodeandcathodecompartments,respectively: ;2H20_4e.?02+4H,

    ;2H20+2e---~H2+2Ot-1-

    ;(1)

    ;(2)

    ;Hproducedfromtheanodereactioninthean. ;odecompartmenttransferredthroughtheCEMunder ;theexternalelectricfieldtoexchangewithCuad. ;sorbedintheCER.TheCERwasregeneratedandthe ;desorbedCuandpartofHmigratedthroughthe ;otherCEMintotheconcentratecompartment.Simi. ;1arly,OHgeneratedfromthecathodereactionmi. ;gratedthroughtheAEMintotheAER.1oadedcom. ;partmenttoreplaceS0:adsorbedintheAER.The

    ;AERwasregeneratedandthenthedesorbedso2,

    ;andpartOf0HtransferredthroughtheotherAEM ;intotheconcentratecompartment.too.Itwaswell ;knownthatthemigrationrateofHwasthegreatest ;amongthoseofcu,s0:,Na,Hand0H,

    ;thereforeHmigratedtotheconcentratecompartment ;earlierthanOH.Underthesameconditions.the

    ;numberofHtransferredtotheconcentratecorn. ;partmentwaslargerthanthatOf0H.andthisacidic

    ;environmentwasveryfavorableforavoiding ;Cu(OH)2precipitationintheconcentratecompart- ;ment.

    ;Furthermore,CuandOHwouldnotcoexistin

    ;CERorAER.Consequently,hydroxideprecipitation ;wou1dnotoccur.

    ;Time(h)

    ;Fig.3pHvalueoftheconcentratedsolutionwithrela-

    ;tivetotimeat(a)differentinletpHvaluesand(b) ;differentappliedvoltages

    ;Table2-IgQcofCuandOH-duringwaterpurification ;Note:lgKspofCu(OH)~isequalto19.66

    ;

     ;Fengeta1./JZhejiangUnivSciA2oo89(9):1283-1287;tertreatment

    ;TheEDIperformancewasevaluatedintermsof ;removalefficiency(re)(Mardereta1.,2004)and ;enrichmentfactor(,definedrespectivelybyEq.(3) ;andEq.(4):

    ;:F_×100%,

    ;G

    ;,

    ;whereGandCfaretheinitialandfinalconcentrations ;oftheion,respectively;Ccistheconcentratedcon

    ;centrationoftheion.

    ;AsshowninFigs.2aand2b.Cuzcouldbe

    ;concentratedashighas245-707mg/L,andthecor

    ;respondingenrichmentfactorwasabout5-14. ;AccordingtoFig.2.thefinalconcentrationOf ;Cuz.removalemciencyofCwas99.54%

    ;99.96%.

    ;C0NCLUS10N

    ;TheinletpHvalueandappliedvoltagehada ;remarkableinfluenceoncopperenrichmentandwater ;purification.AmoderatedecreaseintheinletpH ;valueandamoderateincreaseintheappliedvoltage ;couldachieveabetterremovalefrect.

    ;DuringtheEDIprocess.theconcentratedsolu. ;tionswerealwaysacidenoughtopreventprecipita

    ;tionofmetalhydroxidewhichwascommoninother ;EDIprocesses,andthissuggestedthattheimproved ;EDIconfigurationcouldfeasiblyrealizecontinuous ;andlongtermwastewaterpurification.

    ;Treatmentofcoppecontainingsimulatedelec

    ;troplatingwastewaterbyusingtheimprovedEDI ;configurationshowedthatthewastewaterwaspur1 ;fiedandcouldbedrainedorrecycledforreuseinthe ;electroplatingindustry.

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