ABSTRACTAnovelmethodtoimprovefluxofnanofiltrationc

DesalinationandWaterTreatment©2011DesalinationPublications.Allrightsreserveddoi:10/5004/dwt.2011.2854*Correspondingauthor.34(2011)37–43OctoberAnovelmethodtoimprovefluxofnanofiltrationcompositemembranepreparedbyinterfacialpolymerizationZhouYonga,b,*,LiZhaokuic,DaiZhenanb,WuFadongb,GaoCongjiea,baCollegeofChemistryandChemicalEngineering,OceanUniversityofChina,Qindao266100,ChinaTel.+86-5712-88935362;Fax:[phone];email:[e-mail]ofWaterTreatmentTechnology,Hangzhou310012,ChinacTheInstituteofSeawaterDesalinationandMultipurposeUtilization,SOA,Tianjin300192,ChinaReceived3September2010;Accepted3January2011ABSTRACTThinfilmcomposite(TFC)nanofiltration(NF)membranesbasedpolyamidewerepreparedwithpiperazine(PIP)andtrimesoylchloride(TMC)throughinterfacialpolymerizationtechniqueonthepolysulphonesupportingfilm.Thepoly(dimethylsiloxane)(PDMS)wasaddedinoilTMCsolutiontooptimizemembraneperformance.TheresultsshowedthatcomparedwiththeNFmembranewithoutaddingPDMS,theNFmembranewithaddingPDMShadhigherwaterflux(maximumabout2times);andrejectionforPEG200andNaCldecreasedwithincreaseofMolecularweightofPDMS,butRejectionforNa2SO4keepstable.Theaverageroughness(Rq)ofNFmembraneincreasedwiththemolecularweightofPDMSincreasingbytheAFMresults,higherRqleadstobiggereffectivearea.ThebestPDMSwithmolecularweight63000wasobtained.WithPDMS63000contentincreasing,themolecularweightcutoff(MWCO)ofNFmembranewithPDMS63000increasedfrom200Dato340Da,thefluxincreasedfrom40l/m2·hto70l/m2·hat1.0MPa,whiletherejectionforNa2S04unchangedwiththeconcentrationofPDMSincreasingwhenPDMS63000contentwaslessthan0.5%.Keywords:Poly(piperazineamide);Nanofiltration;Poly(dimethylsiloxane);Thin-filmcompositemembrane;Interfacialpolymerization;Molecularweightcutoff1.IntroductionThinfilmcomposite(TFC)membranes,includingReverseosmosis(RO)membranesandNanofiltration(NF)membraneshavebeensuccessfullyappliedincom-mercialwatertreatmentandwaterpollutioncontrol[1–5].Anumerousnewpolymericmaterialsforthinfilmsofactivelayers[6–8]andsomenovelmembraneprepar-ingmethods[9–11]leadtothecurrentworldwideexpan-sionanddiverseapplicationoftheRO/NFtechnology.RejectionandthefluxaretwoessentialdirectparametersofmembraneintheRO/NFprocesswhichdeterminedbythesolubilityanddiffusivityofsolutesandsolventstotheactive-layerpolymers[12].MuchattentionwasfocusedonhowtoimproveTFCmembranefluxbecausehighmem-branefluxmeanstohighfiltrationefficiency.Zhangetal.[13]preparedanewmaterial,sulfonatedcardopoly(aryleneethersulfone)bearingpendantaminogroups,andmixedwithm-Phenylenediamine(MPD)inaqueousphaseforpreparingthehighfluxcompositeROmembranes.Mansourpanahetal.[14]studiedtheeffectsofadditionofcationiccetyltrimeth-ylammoniumbromide(CTAB),non-ionic(TritonX-100)andanionicsodiumdodecylsulfate(SDS)surfactantsinorganicphaseforpreparingthecompositenanofiltrationmembranesandfoundthatthepreparedmembranesPresentedattheAMS6/IMSTEC10,The6thconferenceoftheAseanianMembraneSocietyinconjunctionwiththe7thInternationalMembraneScienceandTechnologyConference,SydneyAustralia,November22–26,2010