AnovelultrafiltrationUFmembranewithcontrollablesel

Anovelultrafiltration(UF)membranewithcontrollableselectivityforproteinseparationQianLi,Qiu-yanBi,Han-HanLin,Li-XiaBian,Xiao-LinWangnBeijingKeyLaboratoryofMembraneMaterialsandEngineering,DepartmentofChemicalEngineering,TsinghuaUniversity,Beijing,100084,PRChinaarticleinfoArticlehistory:Received3July2012Receivedinrevisedform3September2012Accepted4September2012Availableonline27September2012Keywords:ProteinseparationUltrafiltrationmembraneControllableselectivitySulfobetainepolymerPoly(vinylpyrrolidone)abstractAnovelultrafiltration(UF)membranewithcontrollableselectivityforproteinseparationwasobtainedbyalteringthestructureofthethicksievinglayeronthemembranesurfaceandsubsurface.Poly(vinylpyrrolidone)(PVP)wasfirstcross-linkedon/inthepoly(vinylidenefluoride)(PVDF)hollowfibermicrofiltration(MF)membranetoattractmoresulfobetaine(SB)monomeradjacenttomembraneforsubsequentgraftingpolymerizationandtheformedthicksulfobetainepolymer(PSB)layeronthemembranesurfaceandsubsurfaceactedasthesievinglayerwithenvironmentsensitivity.Afterimmersedin20mmol/LNaClsolutionat601C,thenovelUFmembranewiththesievinglayerof4.8mmshowedhighpermeatecapacitywithawaterfluxof590L/m2handagoodselectivebehaviorwithMWCOof95–110kDa.Theproteinmixture(BSAandLys)couldbeseparatedthroughthenovelUFmembraneefficientlybyisoelectricfocusingofonecomponentwithalargersize(BSA).Bymeansofthesimpleimmersioninpurewater,themembranepermeatedmostofproteinsandthedegreeoffluxdeclinereducedobviously.AfterswelledinNaClsolutionagain,themembranerestoredtheselectivityandtheproteinseparationefficiency.SuchnovelsmartUFmembraneisanattractivecandidateforthebatchseparationofproteinmixtures,expandingthemembraneapplicationinthefieldsofagro-food,biomedicineandotherbio-filtration.&2012ElsevierB.V.Allrightsreserved.1.IntroductionProteinseparationisofgreatimportancefordiversifiedagro-food,biomedicineandotherbio-filtrationapplicationsandresearches[1,2].Manytechniqueshavebeenexploredtoseparateproteinsmixturesinthebiotechindustries,includingproteinadsorbents,capillaryelectrophoresisandsoon[2,3].IthasbeenacknowledgedthatmembraneseparationhaslowenergyContentslistsavailableatSciVerseScienceDirectjournalhomepage:://dx.doi.org/10.1016/j.memsci.2012.09.010Abbreviations:A,outsidesurfaceareaofthemembrane;AFM,atomic-forcemicroscopy;AscA,ascorbicacid;ATR,attenuatedtotalreflectance;BSA,bovineserumalbumin;CAN,cericammoniumnitrate;CfðpÞBSAðLysÞ,concentrationofBSA(Lys)infeed(f)orcollectedpermeate(p)mixtures;CfðpÞi,proteinconcentrationsinthefeed(f)orpermeate(p)solutionsafterithcyclefiltration;CuCl2,copperchloride;d,apparentporediameterofmembrane;Dcut-off,porediameterfromMWCOcalculatedbyhydrodynamicdiameterofdextranorPEO;Dsurface,porediameterfromsurfacemorphologycalculatedbyanalyzingSEMimages;DSC,differentialscanningcalorimetry;FTIR,fouriertransforminfrared;FWF,freewaterfraction;GA,graftingamountofPMPDSAH;HCl,hydrochloricacid;HEMA,2-hydroxyethylmethacrylate;pI,isoelectricpoint;Jv,i,,permeatefluxofproteinsolutionduringithfiltration;JvH2O,i,permeatefluxofpurewaterduringithfiltration;I,ithfiltration;K2S2O8,potassiumpersulfate;Lys,lysozyme;M0,nascentPVDFmembrane;MBAA,N,N0-methylenebisacrylamide;MCP,PVDF-cl-PVPmembrane;MF,microfiltration;Mg2SO4,magnesiumsulfate;MgCl2,magnesiumchloride;mi,permeatemass;MM,PMPDSAH-g-PVDFmembrane;MMCP,PMPDSAH-g-PVDF-cl-PVPmembrane;MMCP-10NC-60,MMCPmembraneafterswellinginthe10mmol/LNaClsolutionat601C;MMCP-20MC-60,MMCPmembraneafterswellinginthe20mmol/LMgCl2solutionat601C;MMCP-20MS-60,MMCPmembraneafterswellinginthe20mmol/LMgSO4solutionat601C;MMCP-20NC-20,MMCPmembraneafterswellinginthe20mmol/LNaClsolutionat201C;MMCP-20NC-40,MMCPmembraneafterswellinginthe20mmol/LNaClsolutionat401C;MMCP-20NC-60,MMCPmembraneafterswellinginthe20mmol/LNaClsolutionat601C;MMCP-20NS-60,MMCPmembraneafterswellinginthe20mmol/LNa2SO4solutionat601C;MMCP-40NC-60,MMCPmembraneafterswellinginthe40mmol/LNaClsolutionat601C;MMCP-5NC-60,MMCPmembraneafterswellinginthe5mmol/LNaClsolutionat601C;MPDSAH,3-(methacryloylaino)propyl-dimethyl-(3-sulfopropyl)ammoniumhydroxide;MW,molecularweight;MWCO,molecularweightcut-off;Na2HPO4,disodiumhydrogenphosphate;Na2SO4,sodiumsulfate;NaCl,sodiumchloride;NaH2PO4,sodiumdihydrogenphosphate;NaOH,sodiumhydroxide;PAN,poly(acrylonitrile);PBS,phosphate-bufferedsaline;PEO,polyethyleneoxide;PMDETA,N,N,N,N,N-pentamethyldiethylenediamine;PMPDSAH,poly(3-(methacryloylaino)propyl-dimethyl-(3-sulfopropyl)ammoniumhydroxide);PSB,sulfobetainepolymer;PVDF,poly(vinylidenefluoride);PVP,poly(vinylpyrrolidone);Ri,rejectionduringithfiltration;RFRi,relativefluxrecoveryduringithfiltration;RMS,meansurfaceroughness;SB,sulfobetaine;SDS-PAGE,Sodiumdodecylsulfatepolyacrylamidegelelectrophoresis;SEM,scanningelectronmicroscope;SF,separationfactor;SMP,surfacemeanporesize;TIPS,thermallyinducedphaseseparation;TOC,totalorganiccarbon;UCST,uppercriticalsolutiontemperature;UF,ultrafiltration;W0,weightofM0orMCPmembrane;W1,weightofMMorMMCPmembrane;XP