A new method for the prediction of pore size distribution and MWCO of ultrafiltration membranes

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1、JournalofMembraneScience279(2006)558569AnewmethodforthepredictionofporesizedistributionandMWCOofultrafiltrationmembranesJizhongRen∗,ZhanshengLi,Fook-SinWongInstituteofEnvironmentalScienceandEngineering,NanyangTechnologicalUniversity,18NanyangDrive,Singapore637723,SingaporeReceived25June

2、2005;receivedinrevisedform3December2005;accepted24December2005Availableonline3February2006AbstractThispaperdescribesthetransportprocess,rejectioncurveandmolecularweightcut-off(MWCO)ofultrafiltrationmembranesbyusingalog-normaldistribution,Poiseuilleflowandstericinteractionbetweensolutemol

3、eculesandpores.TherejectioncoefficientofmembraneswasexpressedwithananalyticalfunctionofD*/a(theratioofgeometricmeandiametertosolutediameter)andσ(geometricstandarddeviation).ForultrafiltrationmembraneswithdifferentMWCO,theporesizedistributioncanbedividedintothreezonesbyσ:ZoneI,longtail-ef

4、fectofbigpores(σ>1.55);ZoneII,linearizationofporesizedistributionparameters(D*,σ)(1.15≤σ≤1.55);ZoneIII,sievingeffect(1≤σ<1.15).TherelationshipbetweenD*/D(DisthediameterofsolutemoleculeatR=0.9)andσwasdescribedbytheExtrememodel:MWCOMWCOD∗σ−1=Ae(−e(−z)−z+1),z=(σ∈[1,∞]),A=1.296,w=0.299DMWC

5、OwForanyrejectioncoefficient,therelationshipbetweenD*/aandσcanalsobedescribedusingtheExtrememodel.AmethodtopredicttheporesizedistributionandMWCOofultrafiltrationmembranesbytwopointswasfirstpresentedandverifiedbyhollowfibermembranesspunatdifferentshearrates.Theshearrateinthespinningofhollowfi

6、bermembranesdominatedtheporesizedistributionparameters(D*,σ),whichplayedanimportantroleinmembraneperformance.Withanincreaseinshearrate,thegeometricstandarddeviation(σ)wasstronglysuppressed,whichresultedinhollowfibermembraneswithlowMWCO.©2006ElsevierB.V.Allrightsreserved.Keywords:Log-nor

7、maldistribution;Rejectioncoefficient;Ultrafiltration;Theory1.Introductiondistributionisveryimportantinadvancingcommercialultrafil-trationmembranes.TheporesizedistributionofultrafiltrationMembraneprocesseshavebeenappliedinvarioustypesofmembranescanbedeterminedbydifferenttechniquessuchasin