Pervaporation of ethanol-water mixtures through poly(vinyl alcohol-g-acrylic acid) membranes prepared by use of Fenton's reagent in grafting

Ionic crosslinking of the ferric ions and the carboxylic groups in the poly(vinyl alcohol-g-acrylic acid) (poly(VA-g-AA)) membranes improves the size screening effect in the pervaporation of ethanol-water separation. In the grafting polymerization of acrylic acid monomer onto poly(vinyl alcohol) (PVA), ferric ions are remained in the polymer membranes as the Fenton's reagent(Fe²⁺-H₂O₂) is used to initiate the reaction. Completely reversed trends in terms of the degree of swelling, the pervaporation selectivity, and the flux of permeates are obtained depending on that the ferric ions are present or absent in the membranes. The degree of swelling decreases, the pervaporation selectivity increases, and the flux decreases as the grafting percentage increases for the membranes containing ferric ions. The degree of swelling and the flux of permeates increase but the pervaporation selectivity is reduced as the grafting percentage increases for the membranes which were washed with acid to remove ferric ions.