生物分离工程英文.pptx

生物分离工程英文.pptx

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BioseparationEngineering,Chapter1Introduction,1.1Downstreamprocessinginbiotechnology,Theproducingprocessofabiotechnologicalproductistermedbioprocess,thatcanbedividedintotwoprocessesasfollowsUpstreamprocessing：

straindevelopmentandbioreaction（enzymecatalyzereaction,microbialfermentation,plant/mammaliancellculture,etc）Downstreamprocessing：

theisolationandpurificationofbiotechnologicalproductsThecomplexityofdownstreamprocessingisdeterminedbytherequiredpurityoftheproduct,inturndeterminedbyitsapplication.,Thedownstreamprocessingschemenormallycanbedividedintothefollowingstages,Broth,Solid-liquidseparation,Extracellularproduct,Intracellularproduct,Celldisruption,Removalofcelldebris,Primaryisolation,purification,formulation,Finalproduct,1.2Demandsonthedownstreamprocessing,StrictlymonitortheDSPstepsforkeepingtheactivityoftheproduct;Rapidlyremovethoseimpuritiescanaffectingthestabilityofthefinalproduct;Generallyitisnecessarytoapplyspecialefficientmethodstothepurificationoftheproduct;Sincemanyproductsareappliedtofood,pharmaceutical,andcosmetics,thosesubstancesharmfultomankindhealthmustberemoved;Sincetheproductconcentrationislowintheculturebroth,itisnecessarytoconcentratethebrothforremovinglargeamountsofwater.Becausethoseofunitoperationsarecostly,thecostofDSPisincreasedobservably.,1.3Separationmechanismandunitoperation,Accordingtodifferentseparationprinciplestheunitoperationscanbesortedintotwogroups：

MechanicalseparationObject：

unhomogeneousphasesystemMechanism：

separationbasedonthedifferenceofsubstancessizeanddensityUnitoperation：

filtration,settling,centrifugation,etc.MasstransferseparationObject：

homogeneousphasesystemTransport/velocityseparationMechanism：

separationbasedonthemigrationvelocitydifferenceofsolutesdrovebybearingaappliedforceUnitoperation：

ultrafiltration,reverseosmosis,electrophoresis,etc.Diffusion/equilibriumseparationMechanism：

separationbasedonthedifferenceofdistributionofsubstancesbetweenthetwophasesUnitoperation：

extraction,crystallization,adsorption,ionexchange,etc.,1.4Estimationforseparationefficiency,Therearethreecriteriaonassessingtheefficiencyofadownstreamprocessing,i.e.concentrationdegree,isolation-purificationdegree,andrecoveryrateConcentrationdegreeGenerallycanberepresentedasconcentratedfactor,Isolation-purificationdegreeCanberepresentedbyseparationfactor/coefficient,Recoveryrate,Chapter2Solid-liquidseparationandcelldisruption,2.1Cellseparation,2.1.1Settling,Stokessettlingvelocityofglobalparticle,Wheredisparticlediameter,sandLarethedensityofparticleandliquid,separately,isresistancecoefficient,ReisReynoldsnumber,andListheviscosityofliquid.,Thevolumeofthecellsissosmallthatitssettlingvelocityisveryslow.Foracceleratingsettlingprocessagglomerationofindividualcellsintolargeflocsisdonebytheadditionofflocculatingagentssuchaspolycations,orinorganicsalts.,2.1.2Centrifugation,Centrifugationvelocity,Whereriscentrifugalradius,isrotaryangularspeed,Nisrevolutionofcentrifuge,andSissedimentationcoefficient.,CentrifugationDifferentialcentrifugationItisanunitoperationcommonlyusedinthebiochemicalindustry.Accordingtothecharacteristicsofthebroth,theaimofisolation,andtheextentofseparationrequested,differentcomponentscanbeseparatedfromthebrothseparatelybyselectingproperoperationalparametersinpractice.ZonalcentrifugationRate-zonaldensitygradientsedimentationIsopycnicdensitygradientsedimentationBesidessucrose,CsClandNaBrcanbeusedforachievingthedensitygradient,andappliedtotheseparationofnucleicacidandlipoprotein,respectively.,CentrifugesThetubularbowlrotorcentrifugeiscommonlyappliedonalaboratoryscale,andthetypesoftubularbowlanddiscstackarecommonlyusedonanindustrialscale.,Theprocessingcapacityofthetubularbowlcentrifugeisdescribedby,WhereListhelengthofthetube,r2istheinsideradiusofthetube,andisusuallycalledtheareaofcentrifugalsedimentation,afunctionofthestructureofthecentrifugeandtheoperatingconditions.,2.1.3Filtration,Definition：

atechnology,applyfiltermediatoretaintheparticlewhileallowingthepassageoftheliquidthroughthefilter,isusedtoachievesolid-liquidseparation.,Theflowthroughthefilter,WhereQisthevolumeofthefiltrate,Aistheareaofthefilter,pisthepressuredifference,Listheviscosityofthefiltrate,RmandRcaretheresistanceofthefiltermediumandthecake,istheaveragespecificresistanceofthecake,andWistheweightofthedriedcake.,Beforefiltrationpretreatmentofthebrothbyadditionofflocculatingagents,theirfunctionhavebeendescribedinSection2.1.1,andprecoatingthefiltermediumwithfilteraids（diatomite,perlite,etc.）areusuallyrequiredtoimprovethefiltrationvelocity.FiltrationequipmentFilterpressandrotarydrumvacuumfilterarefrequentlyusedforclarificationofthebroths.,2.2Celldisruption,Manybiotechnologicalproductscantbeexcretedoutsideofthecellsduringmicroorganismgrow.Forcollectingthoseproductsthefirststepmustberupturingofthemicrobialcellstoreleasetheintracellularcompoundsintotheliquidphase.,2.2.1Cellstructures,Thecellstructuresarequitedifferentamongaconsiderablevarietyofcells.Thesequenceofdifferentcellsbeingbrokenfromdifficulttoeasycanbelistedasfollows:

plantcells,yeastcell,G+cells,G-cells,andanimalcells.Thegoalofcelldisruptionismakingthecellwalland/orcytoplasmicmembranedamagedmoreorlesstoliberatetheintracellularproducts.,2.2.2Theprinciplesofcelldisruption,MechanicaldisruptionTheCellsstructureisbrokenduetothecellsbeingshearedandpressedbymechanicalforces.Asageneralrule,themoresmallthesizeofthecellsis,themorehardtoberuptureditis.Chemical/enzymaticmeansTreatmentwithchemicals/enzymescandamagethecellmembranes/wallsandrendercellsmorepermeable,thatisavailableforreleaseofintracellularproducts.,2.2.3Themeansofcelldisruption,MechanicaldisruptionHigh-pressurehomogenisationPrinciple:

thecellsuspensionisforcedathighpressurethroughanorificeofnarrowinternaldiametertoemergeatatmosphericpressure.Thesuddenreleaseofpressurecreatesaliquidshearcapableofdisruptingthecells.,WhereSisthedisruptionscale,pisoperationalpressure,Niscyclictimes,kisthedisruptionvelocityconstant,correlationwiththekindofthecellsandoperationaltemperature.,Characteristic：

Itisfeasiblefordisruptionofyeastcellsandthemajorityofbacteriacells,butnotsuitablefordisruptionoffilamentousfungus.,Theinfluencingfactors：

pressure,cyclictimes,temperature,etc.,BeadmillingPrinciple：

agitationwithglassinbeadmillsrupturesthecellsbyacombinationofhighshearandimpactwiththecells.,Theinfluencingfactors：

agitationspeed,theconcentrationofcells,theoperatingtime,thebeadsdiameter,density,andloadingdensity.,WhereSisdisruptionratio,kisdisruptionvelocityconstant,correlationwiththebeadsdiameter,density,loadingdensity,theconcentrationofcells,agitationspeed,andtheshapeofthepuddler,tistheoperatingtimeofbatchoperation,orcanbewrittenast=V/Q（Vistheeffectivevolumeofthechamberofthebeadmill,andQisthefeedflux）atcontinueoperation.,Characteristic:

Themethodcanbewidelyappliedtoavarietyofcells,butitisverypoorontheavailableenergy,theabilityoftheheatchangemustbeconsideredinthecoolingsystemdesign.Andbecausemanyoperatingparameterscaninfluencethedisruptionratio,optimizingdesignoftheprocessingisverycomplex.,UltrasonicationPrinciple：

cavitation.Theinfluencingfactors：

thekindandconcentrationofthecells,andtheenergyoftheultrasonication.Characteristic:

itiscommonlyusedatlaboratoryscale;removaloftheheatgeneratedisdifficultonalargerscale.,ChemicalmethodsTreatmentwithchemicalsPrinciple：

see2.2.2Availablechemicals:

acid,alkali,organicsolvents,detergent,chelates,chaotropicagents,etc.EnzymaticlysisPrinciple：

see2.2.2Availableenzymes：

Becausetherearedifferentchemicalcomponentsofcellwallamongavarietyoforganisms,properenzymemustbeselected,e.g.lysozymeissuitablefortreatmentofbacteria;Zymolyase,-1,6-dextranase,ormannanaseisusedforyeast;anddamagingplantcellsneedtoapplycellulase.,Acombinationofenzymatic/chemicallysiswithmechanicaldisintegrationhasbeensuggestedinenhancingtheefficienciesoftherespectivemethods,withsavingsintimeandenergyandthefacilitationofsubsequentprocessing.,PhysicalmeansOsmoticshockPrinciple：

putcellsintoasolutionoflowerosmoticpressuresuddenlyfromthatofhigherosmoticpressure,thatresultinalotofwaterswarmingintocellsandburstingtheperiplasmicmembrane.Characteristic：

itisthemostmildmethodofcelldisruption,butonlyeffectiveforanimalcellsthatlackacellwall.,FreezethawPrinciple：

becauseofwatercrystallizingquantitiesofcrystalnucleusareformedinthecellsduringthecellsarefrozenrapidly,thatcandamagethestructureofthecells.Generallyfreezeandthawmustbecarriedoutagainandagainuntiltheexpectationfortheratioofcelldisruptionismet.Characteristic：

itisonlysuitableforthosecellswhosewallisthinner,anddifficulttobeusedonalargerscale.,Summary:

Sincethestructureamongmanyspeciesofcellandthepropertyofproductsaremuchdifferent,choiceofthedisruptionmethodshastobemadeempirically,atthesametimetakingintoconsiderationthesubsequentprocessingsteps.,Chapter3Precipitation,Definition：

aphenomenaofsolidaggregatesfo