Fig. 4(a) showsthatthesaltrejectionofthedry-castCATFC
membraneissignificantly improvedaftera60minwaterswelling
time. Fig. 4(b) clearlyshowsthatswellinginwaterimprovesthe
stability ofthedry-castCATFCmembrane.Thedry-castCATFC
washighlyunstableunderappliedpressureasshownbythe
reducing flux upto28barandincreasing flux thereafter.Thiscan
be attributedtotheopennon-equilibratedporosityoftheinitial
dry-castselectivelayerthatissubjectedtore-arrangementunder
applied pressure.
Fig. 5 summarizes thepermeabilityandselectivityofthewater-
swollenmembranesasafunctionofthewaterswellingtime.Upto
30 minswellingtime,thepermeabilityandsaltrejectionare
highly fluctuating andresembletheperformanceofthedry-cast
CA TFCmembrane.A60minswellingtimeimprovesthesalt
rejectionto90.6%withadramaticreductioninthepermeabilityto
0.26 lm2 h1 bar1. The flux-selectivity tradeoffisclearly
visible atthispoint.TheseresultssuggestthatthemajorreconfigurationintheCAselectivelayeroccurswithinthe
first 60minin
the waterbath.
Theincreaseinthewaterswellingtimeto120minresultsina
gradualimprovementinthepermeabilitywithaslightincreaseinthe
selectivityto93.5%. Fig. 5 alsoshowsthatprolongedswellingtime
furtherimprovedthewater fluxtoreturntovaluesclosetothedry-
cast CATFCmembranewhilekeepingthesaltrejectionatahighvalue.