PREFERENTIAL SORPTION OF MODIFIED PVA MEMBRANE IN PERVAPORATION

The swelling processes of an annealed poly (vinyl alcohol) membrane, a NaOH-crosslinked poly (vinyl alcohol) membrane, a poly (vinyl alcohol )-N,N'-methylene bisacrylamide irradiation-crosslinked membrane and a poly (vinyl alcohol)/poly(AMcoAANa) blend membrane were investigated. Water was preferentially sorbed by all four membranes. The selective s orption factor alpha(s) and the selective diffusion factor alpha(d) we re defined, and were used to characterize the effects of sorption and diffusion on selectivity. The results have shown that preferential sor ption has a marked effect on selectivity. The mean diffusion coefficie nts and pervaporation properties of the four membranes are also discus sed.