聚丙烯接枝聚丙烯酸中空纤维膜的pH响应性

聚丙烯接枝聚丙烯酸中空纤维膜的pH响应性 聚丙烯接枝聚丙烯酸中空纤维膜的pH响应 性 第46卷增刊 2007年6月 中山大学(自然科学版) ACTASCIENTIARUMNATURALIUMUNIVERSITATISSUNYATSENI Vo1.46Sup. Jun.2oo7 ThepHDependenceofPoly(acrylicacid).graft. P0lypr0pyleneHollowFiberMembrane Yan-ju,LUChun-ying,CHENRui,FUXue-qi (1?EnvironmentalScienceandEngineeringCollege,NanKaiUniversity,Tianjin300071,China; 2.TianjinPolytechnicUniversity,Tianjin300160,China) Abstract:ThepHdependenceofpoly(acrylicacid)一graft— polypropylenemembraneswereeva1uated. TheresultshowsthatDHsensi. tivityofgraftedmembranesincreaseswiththeriseofgraftingdegree(dg)asdg<17%.ForthemicrjltrationofBovinesemma1bu. rain(BSA)solution,allmembranesshowthemostseriousfoulingbehavioratpH4.7(theisoe1ectricpointIEPofBSA)andthe smallestfluxdeclineatpH3.ComparedwiththeungrafiedPPmembrane,graftedmembranesshowmoI?seriousfoulingbehavioratpH 3,whereas18%graftedmembranehasacertainantifoulingbehavioratpH4.7and8.Ithasbeenshownt}lattheelectrica1interactions andtheconformationofBSAandgraftedchainsshouldbeconsideredtoanalyzethefoulingbehavior. Keywords:pHsensitivity;waterpermeability;Bovineserumalburain:microfihration CLCnumber:TQ325.14Documentcode:AArticleID:0529-6579f2007)Sl-0296-02 ThepHsensitivemembranethatcanresponset0 pHstimulushasbeenextensivelystudied~引.These membraneshavebeenexpectedmanypotentialapplica. tionsrangingfromselectiveseparationstocontrolled. releasedsystems..pH—sensitivitymembraneswerere. portedanalleviatedfoulingbehaviorforthemicrofihra. tionofdrinkingwater【.Inthiswork,theDH.sensitiv. ityandtheBSAmicrofihrationofpoly(acrylicacid). graft—polypropyl—enemembraneswerestudied. 1Experimental 1.1Materials Thepoly(acrylicacid)一graft—polypropylenemem. braneswerepreparedbyUV—photograftion. 1.2Themicrofiltrationexperiments ThemicrofihrationexpeHmentswerecarriedoutat 25?2oCunderatransmembranepressureof100kPa withaflowrateof100L/h.Membraneswerewetted with70%ethanolsolutioninadvance. 2Resultsanddiscussion 2.1pHsensitivityofwaterpermeability InFig.1..duetothenon.ionizabilityofPPmem— brane,ithasnoresponsetopH.Whiletheconform. ationofthepolyacrylicacid(PAA)chainsongrafted membraneschangesfromcoiledatlowpHtoextended athighpH.Thus.anincreaseinpHresultsindra. maticfluxdeclinefromthemaximumatpH1t0the minimumatpH11 O 0246810l2 pH Fig.1Flux—pHdependenceofmembranes AccordingtotheHagen—poiseuillelaw…. the changingratioN1/l1ofporesizeaspHwasalteredfrom 1toI1wascalculatedasfollow: ?J/JJrpH1() FromFig.2:asdg<17%,Nl/11increaseswith theriseofdg,whichindicatespHsensitivityofgrafted membranesisimproved.Whereasasdg>17%,many poresareconstrictedorblockedbyPAAchains【. whichcausesalossonpHsensitivity.Thecure0f N?ishigherthanthatofNl1, whichmeansgrafted membranesaremoresensitiveinalkalines0luti0ndue totheswiftriseofchargedensity. 2.2MembranefoulingduringBSAmicrofiltration FromFig.3:?Allmembranesshowthemost 收稿日期:2007-01—10 作者简介:刘燕军(1972年生),女,副研究员;通讯联系人:傅学起;E-mail:fuxueqi@nankai.ed.cn ???湖瑚 一Il), 增刊刘燕军等:聚丙烯接枝聚丙烯酸中空纤维膜的pH响应性297 2.8 2.4 2.0 1.6 1.2 0.8 Fig.2ChangingratiosindifferentpHranges pronouncedfluxdeclinedrivenbythehydrophobicin. teractionsbetweenBSAandmembraneatpH4.7.The hydrophilicsurfaceofgraftedmembranesalleviatesthe absorptionofBSA,SOthelargerdgleadstotheslower fluxdecline.(AtpH3,5%PAAchainsdissociate andattractthepositiveBSA.Sothehigherofdg,the worsefoulingis.?Aftergrafting.membranesurface becomescoarser,whichprovidesmoreabsorbingposi— tionforBSA.AtpH8,therepulsiveforcebetween PAAandBSAcanovercomethiseffectathighdg:As aresult,18%graftedmembranehasanantifoulingbe— havior. pH=3'.一 pH.7口] O2O40608Ol0Ol20l40 t/rain Fi昏3TheBSAfiltrationbehaviorofmembranes Inalkalisolution,BSAmoleculehasmorehydro— phobicsurface[andiseasiertoaggregateonmen. branesurface.Asaresult,theBSAfoulingtomen— branesiSmoreseriousinalkalinesolution. 3Conclusion (1)ThepHsensitivityofgraftedmembranesin— creasewiththeriseofgraftingdegreeasdg<17%. (2)Allmembraneshavethemostseriousfouling atpH4.7andfollowedbypH8.AtpH3,morefoul— ingtakesplaceforgraftedmembranes.AtpH4.7and 8,18%graftedmembranepresentscertainantifouling behavior. (3)Theelectrostaticinteractionandtheconfor. marionofBSAandthemembranesurfacearethemain factoraffectingmembranefouling. References: CHENL,TIANZ,DUY.SynthesisandpHsensitivity ofcarboxymethylchitosan—basedpolyampholytehydrogels forproteincarriermatrices[J].Biomaterials,2004, 25(17):3725.3732. WANGY,LIUZ,HANB.pHSensitivepolypropylene porousmembranepreparedbygraftingacrylicacidinSH- percriticalcarbondioxide[J].Polymer,2004,45 (3):855—860. HAACKJM,BOOKERNA,CARROLLTA.Permea? bility—controlledmicrofihrationmembraneforreduced foulingindrinkingwatertreatment[J].WarRes, 2003,37(3):585-588. ZHUCL.MembraneScienceandTechnology[M]. Beijing:HigherEducationPress,2003:105. WEIXF,DINGXM,LIUHZ.Spectralstudyofthe microenviromentchangeofaromaticaminoacidresidues inBSAinducedbypH[J].SpectroscopyandSpectra Analysis,2000,20(4):556-559. 聚丙烯接枝聚丙烯酸中空纤维膜的pH响应性 刘燕军,吕春英,陈蕊,傅学起 (1.南开大学环境科学与工程学院,天津300071;2.天津工业大学材料化工学院,天 津300160) 摘要:评价了聚丙烯酸接枝改性聚丙烯中空纤维膜的pH响应性.在接枝率小于 17%时,接枝膜的pH敏感性随接枝率 的增加而提高.在牛血清蛋白(BSA)溶液微滤试验中,接枝膜与未接枝膜在BSA的等电点4.7处,都表现出严重的膜污 染;而pH=3时,膜通量下降趋势最小.与未接枝膜相比,接枝膜在pH=3时污染较严重,而接枝率18%的膜在pH4.7 和8时表现出一定的抗污染性.研究表明:蛋白质与膜之间的电荷作用以及BSA和膜构象的变化都是膜污染的重要影响因 素. 关键词:pH敏感性;水渗透性;牛血清蛋白;微滤 中图分类号:TQ325.14 ?洲 【J1蓍罾呈u