Study of Reverse Osmosis Separation and Permeation Rate for Sulfonated Poly(2,6-dimethyl-l,4=phenyle

StudyofReverseOsmosisSeparationandPermeationRateforSulfonatedPoly(2,6-dimethyl-l,4=phenyleneoxide)MembranesofDifferentIonExchangeCapacitiesAllHAMZA,GEETACHOWDHURY,1.MATSUURA,*andS.SOURIRAJANIndustrialMembraneResearchInstitute,DepartmentofChemicalEngineering,UniversityofOttawa,Ottawa,Ontario,Canada,K1N6N5SYNOPSISThereverseosmosisperformanceofthin-filmcompositemembranespreparedfromsul-fonatedpolyphenyleneoxidepolymerwithdifferention-exchangecapacitieswasstudiedusingvariouselectrolytesolutes.Theeffectofthesolventusedforthepreparationofthepolymersolutionforsurfacecoatingwasalsostudied.Itwasfoundthatthepreparationofthin-filmcompositemembraneswithhighselectivitiesandhighfluxeswaspossiblebyadjustingproperlytheion-exchangecapacityandthesolvent.Itwasalsofoundthatthemembraneperformancewasgovernedprimarilybytheion-exchangereactionbetweenthesolutecationandtheprotoninSO,HandtheDonnanequilibrium.01995JohnWiley&Sons,Inc.INTRODUCTIONIntherecentyearsanumberofchargedthin-filmcompositemembraneshavebeendeveloped.Thesemembranesexhibithighwaterfluxandareresistanttochlorine,highandlowpH,andhightempera-ture.','Theselectivityofthesemembranesispri-marilycontrolledbytheelectricchargeofthethinselectivelayeratthemembranesurface.Becauseofthethinnessoftheselectivesurfacelayer,thechargedcompositemembraneisalsofeaturedbyahigherfluxoraloweroperatingpressurethanthoseofneutralmembrane^.^,^Thisprinciplehasbeenappliedindustriallyforthedevelopmentofnano-filtrationmembraneswhoseperformancecharac-teristicsarebetweenthoseofreverseosmosisandultrafiltrationmembranes.Studiesontheperformanceofchargedcompositemembraneshavebeenreportedbyanumberofau-thor~.~-~Normally,themembranesarenegativelycharged,andelectrolytesoluteswithhigheranionicchargedensitiesand/orwithlowercationicchargedensitiesarerejectedmoreeffectively.Ontheother*Towhomcorrespondenceshouldbeaddressed.JournalofAppliedPolymerScience,Vol.58,613-620(1995)01995JohnWiley&Sons,Inc.CCC0021-8995/95/030613-08hand,therejectionofsoluteswithoutelectricchargeisless