防污膜表面改性.ppt

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1、SurfaceModificationsforAntifoulingMembranesBackgroundfouling=depositiontypesparticles,colloids,macromolecules,salts,etc.Temporary:theinitialfluxcanberestoredbywashingthemembraneorbyapplyingback-pressuresPermanent:cannotberestoredcause:theinteractionbe

2、tweenthemembranesurfaceandthefoulants.(inorganic,organic,andbiologicalsubstancesinmanydifferentforms)reasons:Thefoulantswillchemicallydegradethemembranematerial,destroyofmembranestructure.Fouling,atthemembranesurfaceorinsidetheporeattheporewall,reduce

3、sthemembraneflux.periodicalwashingwithchemicals,suchassodiumhypochloritesolution,willresultinthesimultaneousdegradationofthemembranematerial’slifetime.theskinlayerortopsurfacelayerplaysthevitalroleintheseparationprocessbymembrane,whichisessentiallyasu

4、rfacephenomenonModificationmethodTosomeextent,selectionofanappropriatemembrane,pretreatmentoftheprocessfluid,adjustmentofoperatingdesignandconditionsareallknowntocontrolfoulingincreasehydrophilicity.becauseproteinandmanyotherfoulantsarehydrophobicinna

5、tureelectricallychargedwhichsignificantlyreducesthescale-formationsurfaceroughnessItisbelievedthatthemembranefoulingwithparticulatesubstanceisenhancedbyanincreaseinthesurfaceroughnessproblemThesimultaneouschangesintheotherparameters,whenoneoftheparame

6、tersischanged,makethestudyofmembranefoulingevenmoredifficult.howmuchthesurfacemodificationcancontributetothefoulingreduction,Oncethedepositionoffoulantshastakenplace,thesurfacemodificationisnolongereffectivetopreventfoulingTHANKYOU