PolysulfoneChitosanblendultrafiltrationmembranespr

Citethis:RSCAdvances,2013,3,7855Polysulfone–Chitosanblendultrafiltrationmembranes:preparation,characterization,permeationandantifoulingpropertiesReceived7thJanuary2013,Accepted14thMarch2013DOI:10.1039/c3ra00070b*aA.F.Ismail,bSurayaA.RashidcandT.MatsuuradBiocompatibleandnaturallyoccurringchitosanwasusedasanadditiveforthepreparationofapolysulfoneultrafiltrationmembrane.TwodifferentcompositionsofpolysulfoneinN-methylpyrrolidone(NMP)andchitosanin1%aceticacidwereblendedtopreparePSf–CSultrafiltrationmembranesbythediffusioninducedphaseseparation(DIPS)method.TheproperblendingofpolysulfoneandchitosaninPSf–CSmembraneswasconfirmedbyATR-IRanalysis.Thesurfaceandcross-sectionalmorphologyofthemembraneswasstudiedbyscanningelectronmicroscopy(SEM).Themembranehydrophilicitywasdeterminedbywateruptakeandcontactanglemeasurements.ThePSf–CSmembraneshowedanenhancedhydrophilicitycomparedtoaPSfultrafiltrationmembrane.ThetimedependentpermeationstudiesrevealedtheimprovedfluxofPSf–CSmembranes.PSf–CSmembranesweresubjectedtobovineserumalbumin(BSA)proteinrejectionstudies.AnimprovedantifoulingpropertywasobservedforPSf–CSblendmembranesascomparedtopristinePSfultrafiltrationmembranes.BoththepermeationandantifoulingpropertiesofPSf–CSmembranesincreasedwithanincreaseinchitosancomposition.1.IntroductionMembraneprocesseshavemetalargeexpansioninthepurificationofwaterinthelastfewdecades.Ultrafiltrationmembranesareconsideredaspretreatmentmembranespriortoreverseosmosisinthedesalinationprocess.Whereultrafiltrationmembranesareconcerned,thehydrophilicityofthemembranesandtheirporousstructureplayanimportantroleinthemembraneseparationprocess.Asuitableporousmembranemusthavehighpermeability,goodhydro-philicityandexcellentchemicalresistancetowardsthefeedsolution.1Polysulfoneisanoutstandingultrafiltrationmem-branematerialbecauseofitsexcellentoxidative,thermalandhydrolyticstabilitywithgoodflexibility,resistancetoextremesofpHandgoodmechanicalandfilmformingproperties.2Alsoitiswidelyusedtoprepareasymmetricmembraneswithdifferentporesizesformicrofiltrationandnanofiltrationapplications.3–6Despitethesebenefits,themaindisadvantageofthispolymerisitshydrophobicnaturewhichmakesitpoorinpermeationandantifoulingproperties.7–10Itsratherhydrophobicnatureisaconsiderablelimitationinsomeaqueousmembraneapplicationsthatdemandanhydrophiliccharacter.Hydrophilicityenhancementhasbeenachievedbyvariousphysicalandchemicalsurfacetreatmentproceduresonpreformedpolysulfonemembranesorbyblendingthecastingsolutionsofthemembraneswithseveralhydrophilicorganicorinorganicadditives.11–15Blendingistheclassicaltechniqueformembranemod-ification.Similartocoatingandgraftingmethods,blendingresultsinachangeintheporesizeofthemembrane.Oneoftheblendingmethodsisthedirectmixingofhydrophilicmacromoleculeswiththehostmembranematrix,whichmakestheremovalofhydrophobicmaterialsfromthefeedsolutionrelativelyeasy.16Chitosanisanabundantnaturalbiopolymerwhichisbiodegradable,hydrophilicandshowsanexcellentfilmformingnature.Chitosanmembranesarebeingusedinseparationprocessessuchasnanofiltration,ultrafiltration,pervaporationandreverseosmosis.17–21Intheliteratureonecanfindpolysulfoneandchitosanormodifiedchitosan–polysulfonecompositemembranesinthefieldofnanofiltra-tion.17,22,23Thecommonprocedureofmembranepreparationiscastingthechitosansolution(eitherinacidicorneutralmedia)onthesurfaceofasupportmembranetoformathinlayer(sometimescross-linkingisalsoreported19,22,23).Asurfacethinlayerincreasesthehydrophilicitytherebyenhan-cingthepermeationpropertyofthemembrane.IntheliteraturetherearereportsonthecastingofanacidicchitosansolutiononthesurfaceofapolysulfonesupporttoaMembraneTechnologyLaboratory,ChemistryDepartment,NationalInstituteofTechnologyKarnataka,Surathkal,Mangalore575025,India.E-mail:[e-mail];Fax:[phone]bAdvancedMembraneTechnologyResearchCenter(AMTEC),UniversitiTeknologiMalaysia,81310UTM,Skudai,Johor,MalaysiacAdvancedMaterialsandNanotechnologyLaboratory,InstituteofAdvancedTechnologyUniversitiPutraMalaysia,Selangor,MalaysiadDepartmentofChemicalandBiologicalEngineering,UniversityofOttawa,CanadaRSCAdvancesPAPERThisjournalisTheRoyalSocietyofChemistry2013RSCAdv.,2013,3,7855–7861|7855Publishedon14March2013.DownloadedbyCornellUniversityLibraryon04/08/201408:05:32.ViewArticleOnlineViewJournal|ViewIssuegetcompositemembranesforwaterpurificationandperva-porationapplications.24–27Inthepresentwork,duetotheinsolubilityofchitosaninorganicsolvents,amodifiedprocedurefortheblendingofpolysulfonewithchitosanwasreported.Twoultrafiltrationmembraneswithdifferentcon-tentsofchitosan(astheadditive)intheblendwereprepared.Furthermore,theeffectofchitosanonthepermeationandantifoulingpropertiesofthemembraneswasstudied.2.Materialsandmethods2.1.MaterialsPolysulfone(PSf)withamolecularweightof35000Daandlowmolecularweightchitosan(degreeofdeacetylation75–85%)werepurchasedfromSigma-AldrichCo.Bangalore,India.1-Methyl-2-pyrrolidone(NMP)andaceticacidwerepurchasedfromMerckIndia,Ltd.Bovineserumalbumin(BSA)waspurchas