一膜技术基础课件

黄征青湖北工业大学化学与环境工程学院BasicPrinciplesofMembraneTechnologySecondeditionMarcelMulder膜技术基本原理ContentsChapter1：IntroductionChapter3：Preparationofsyntheticmembanes

Chapter4：CharacterazitionofmembranesChapter6：MembraneprocessesandtheirapplicationChapter7：Polarizationphenomenaandmembranefouling主要参考书1.

时钧，袁权，高从阶主编，膜技术手册，化学工业出版社2.

朱长乐，刘茉娥，朱才全，“化学工程手册”第18篇，“薄膜过程”，北京，化学

工业出版社，19873.

王湛编，膜分离技术基础，北京，化学工业出版社，20004.

刘茉娥等编著，膜分离技术，化学工业出版社，20005.

刘茉娥等编著，膜技术应用手册，化学工业出版社，20016.

李基森，许景文，徐元耀等。离子交换膜及其应用，北京：科学出版社，19777.

王振坤编，离子交换膜一制备，性能及应用，北京：化学工业出版社，19858.

张维润等著，电渗析工程学，北京：科学出版社，19959.

李琳译，膜技术基本原理（第二版），北京：清华大学出版社，199910.高以垣，叶凌碧，膜分离技术基础，1989，北京：科学出版社主要刊物膜科学与膜技术水处理技术JournalmembraneSci；JMembBio,Desalination高分子类：

Polymer,Polymerint,JApplPoly,JPolySci,Macromolecules电化学类

：JApplElectrochem,JElectroAnaChem分离工程类：

SepSciTec,SepPurimethod/Technology环境、界面、食品IIntroductionHowdoyougetapurecomponentfromamixture?Canthisprocesshappenspontaneously?1.1.AnalysisofthermodynamicsCHHHCHCHCCCCCCCHHHHHH(a)(b)Whatmethodscanyouusetogetapurecomponentfromamixture?

Distillation,evaporation,蒸馏，蒸发Crystallisation结晶Extraction萃取Assimilation吸收Centrifugation离心Filtration过滤Dryness干燥Adsorption吸附affinitychromatography亲和色谱1.2.Generalcriteriaforthechooseofaseparationprocess

Twogeneralcriteriaapplytoallseparationprocesses:1).Theseparationmustbefeasibletechnically(becapableofaccomplishingthedesiredseparationandachieveaqualityproduct);2).Theseparationmustbefeasibleeconomically.1.3.TheobjectivesofseparationConcentration浓缩:thedesiredcomponentispresentinalowconcentrationandsolventhastoberemoved.Purification纯化:undesirableimpuritieshavetoberemoved.purification:undesirableimpuritieshavetoberemoved.Fractionation分级:amixturemustbeseparatedintotwoormoredesiredcomponents.Reactionmediation反应调节:combinationofachemicalorbiochemicalreactionwithacontinuousremovedofproductswillincreasethereactionrate.Fig.I.2Schematicrepresentationofamembraneprocesswherethefeedstreamhasbeenseparatedintoaretentateandapermeatestream.feedretentatepermeatemodule进料液截留液渗透液膜组件Thefollowingdrawbacksshouldbementioned:-Concentrationpolarization浓差极化/membranefouling膜污染;-Lowmembranelifetime;-Lowselectivity选择性orflux通量;-Up-scalingfactorismoreorlesslinear.2.Introductiontomembraneprocesses2.1.Introduction2.2.Theparametersofmembraneperformance（膜性能参数）feedPhase1membranePhase2permeateDrivingforce△C,△P,△T,△EFig.I.3Schematicrepresentationofatwo-phasesystemseparatedbyamembrane物质透过膜的主要三种方式：被动传递促进传递主动传递◆

被动传递：物质由高化学位相向低化学位相传递，这一化学位的差就是膜分离过程的推动力。压力差浓度差电位差温度差推动力AAμ‘Aμ‘’Aμ‘A>μ‘’A被动传递◆促进传递：膜内有载体，在高化学位一侧，载体同被传递的物质发生反应，而在低化学位一侧又将被传递的物质释放，这种传递过程有很高的选择性。μ‘A>μ‘’AA+B→ABAAB→A+BAμ‘Aμ‘’A促进传递BAB◆

主动传递：膜中的载体同被传递物质在低化学位侧发生反应并释放能量，使被传递物质由低化学位一侧被传递到高化学位一侧，物质的传递方向为逆化学位梯度方向。μ‘A<μ‘’AA+B→ABAAB→A+BAμ‘Aμ‘’A化学反应主动传递BAB2.2.TheparametersofmembraneperformanceFlow流量(oftendenotedastheflux通量orpermeationrate渗透速率):Flowisdefinedasthevolumeflowingthroughthemembraneperunitsareaandtime.Volumefluxmaybereadilyconvertedtomassfluxormolefluxbyusingthedensityandmolecularweight.（单位推动力下）物质在单位时间内透过单位面积膜的量。Inordertocomparegasfluxeswitheachotherthevolumeisalwaysgivenunderstandardconditions(STP)whichisat0℃and1atmosphere(=1.0013bar).JVA*t=Selectivity

选择性：不同物质在两相中的浓度变化比Theselectivityofamembranetowardsamixtureisgenerallyexpressedbyoneoftwoparameters:theretention(R)ortheseparationfactor(α).Membraneselectivitytowardsgasmixturesandmixturesoforganicliquidsisusuallyexpressedintermsoftheseparationfactorα.ForamixtureconsistingofcomponentsAandBtheselectivityfactorαA/Bisgivenby

αA/B=(yA/yB)/(xA/xB)WhereyAandyBaretheconcentrationsofcomponentsAandBinthepermeateandxAandxBaretheconcentrationsofcomponentsAandBinthefeed.Theselectivityischoseninsuchawaythatitsvalueisgreaterthanunity.ThenifthepermeationrateofcomponentAthroughthemembraneislargerthanthatofcomponentB,theseparationfactorisdenotedasαA/B;ifcomponentBpermeatespreferentially,thentheseparationfactorisgivenbyαB/A.

3.ThehistoryofmembranetechnologyEventowardsthemiddleofeighteenthcenturymembranephenomenawereobservedandstudied,primarilytoelucidatethebarrierpropertiesandrelatedphenomenaratherthantodevelopmembranesfortechnicalandindustrialapplications.

TableI.2Developmentof(technical)membraneprocessesmembraneprocesscountryyearapplicationmicrofiltrtion+Germany1920laboratoryuse(bacteriafilter)ultrafiltration+Germany1930laboratoryusehemodialysis+Netherlands1950artificialkidneyelectrodialysis*USA1955desalinationreverseosmosis*USA1960seawaterdesalinationultrafiltration*USA1960concentrationofmacromolecuesgasseparation*USA1979hydrogenrecoverymembranedistillation+Germany1981concentrationofaqueoussolutionspervaporation*Germany/Netherlands1982dehydrationoforganicsolvent+smallscale*industrialscaleAbreakthroughforthemembranepreparationwasthedevelopmentofasymmetricmembranes(LoebandSourirajan).Thesemembranesconsistofaverythindensetoplayer(thickness<0.5μm)supportedbyaporoussublayer(thickness50-200μm).Thetoplayerorskindeterminesthetransportratewhiletheporoussublayeronlyactsasasurport.Thepermeationrateisinverselyproportionaltothethicknessoftheactualbarrierlayerandthusasymmetricmembranesshowamuchhigherpermeationratethan(homogeneous)symmetricmembranesofacomparablethickness(RO).AnotherbreakthroughwasfromtheworkofHenisandTripodi.Theyplacedaverythinhomogenouslayerofapolymerwithhighgaspermeabilityontopofanasymmetricmembrane,ensuringthattheporesintoplayerwerefilledandthataleak-freecompositemembranesuitableforgasseparation4.DefinitionandClassificationofamembrane4.1.DefinitionofamembraneAlthoughitisdifficulttogiveanexactdefinitionofamembrane,ageneraldefinitioncouldbe:Aselectivebarrierbetweentwophases,theterm‘selective’beinginherenttomembraneoramembraneprocess.4.2.

ClassificationToobtainamoreinformativeunderstanding,membranescanbeclassifiedaccordingtodifferentviewpoints.Thefirstclassificationisbynature,i.e.biologicalorsyntheticmembrane,thisistheclearestdistinctionpossible.Anothermeansofclassifyingmembranesisbymorphologyorstructure.SolidmembraneNon-livingmembraneLiquidmembraneEmulsionliquidmembraneSupportedliquidmembraneOrganicmembraneInorganicmembraneBiologicalmembranesSyntheticmembranesMembranesLivingmembraneMembranesNonporousmembraneCylindricalPorousmembanePorousmembraneL-SmembraneCompositemembraneSymmetric(isotropic)membranesAsymmetric(Anisotropic)membranes5.Membraneprocesses5.1MembraneprocessesanddrivingforcesInmanycasesthepermeationratethroughthemembraneisproportionaltothedrivingforces,i.e.theflux-forcerelationshipcanbedescribedbyalinearphenomenologicalequation.Proportionalitybetweentheflux(J)andthedrivingforceisgivenbyJ=-AdX/dxWhereAiscalledthephenomenologicalcoefficientand(dX/dx)isthedrivingforce,expressedasthegradientofX(temperature,concentration,pressure)alongacoordinatexperpendiculartothetransportbarrier.Phenomenologicalequationscanbeusedtodescribemassflux,heatflux,volumeflux,momentumfluxandelectricalflux.TableI.4PhenomenologicalequationsmassfluxJm=-Ddc/dx(Fick)D(thediffusioncoeffient)volumefluxJv=-LpdP/dx(Darcy)Lp(permeabilitycoeffient)heatfluxJh=-λdT/dx(Fourier)λ(thermaldiffusivity)momentumfluxJn=-υdv/dx(Newton)υ(=η/ρkinematicviscosity)electricalfluxJi=-l/RdE/dx(Ohm)l/R(electricalconductivity)

LLLGGGDrivingforcePhase

1Phase2membraneFig.I.7Schematicrepresentationofphase

divided

by

amembraneForapurecomponentpermeatingthroughamembrane,itispossibletoemploylinearrelationstodescribetransport.However,whentwoormorecomponentspermeatesimultaneously,suchrelationscannotbegenerallyemployedsincecouplingphenomenamayoccurinthefluxesandforces.Thesecouplingphenomenacanbedescribedintermsoftheformalismofnon-equilibriumthermodynamics.TableI.4Somemembraneprocessesanddrivingforcesmembraneprocessphase1phase2drivingforcemicrofiltration(微滤)LLΔPultrafiltration(超滤)LLΔPnanofiltration(纳滤)LLΔPreverseosmosis(反渗透)LLΔPpiezodialysis(加压渗析)LLΔPgasseparation(气体分离)GGΔPvaporpermeation(蒸发渗透)GGΔPpervaporation(渗透蒸发)LGΔPelectrodialysis(电渗析)LLΔEmembraneelectrolysis(膜电解)LLΔEdialysis(渗析或透析))LLΔcdiffusiondialysis(扩散渗析)LLΔcmembranecontactors(膜接触器)LLΔcGLΔc/ΔPLGΔc/ΔPthermo-osmosis(热渗透)LLΔT/ΔPmembranedistillation(膜蒸馏)LLΔT/ΔP5.2.Applicationrangeofvarious

membraneprocessesumARELATIVESIZEOFCOMMONMATERIAL过滤对象MOLECULARWEIGHT分子量0.001100.011000.110001.01041010510010001061071002005,00020,000150,000500,000Aqueoussalts水中盐份Metalions金属离子Sugars蔗糖FILTRATIONTECHNO-LOGY过滤方法Pyrogens热源Virus病毒Colloidalsilica胶体硅Albuminprotein白蛋白Bacteria细菌Carbonblack碳黑Paintpigment颜料色素Yeastcells酵母Milledflour面粉Beachsand海滩沙砾Pollens花粉RO反渗透Ultrafiltration超滤Microfiltration微滤Particle

filtration一般过滤THEFILTRATIONSPECTRUM过滤谱图NF纳滤1.Afeedsolutionwithasoluteconcentrationof3%byweightistreatedbyreverseosmosis.Thepermeatecontains150ppmofsolute.CalculatetheretentionRandtheselectivityfactora.explainwhichofthetwoparametersismoresuitableforthisapplication.2.Air(20%oxygenand80%nitrogen)isseparatedbyamembraneandapermeateconcentrationof75%ofoxygenisobtained.CalculatetheretentionRandtheselectivityfactora.explainwhichofthetwoparametersismoresuitableforthisapplication.3.Giveacompariso