Pervaporation separation of an azeotropic mixture of a tetrahydrofuran-water system with nanostructured polyhedral oligomeric silsesquioxane embedded poly(vinyl alcohol)

Cage - structured polyhedral oligomeric silsesquioxane (POSS) molecules were used as modifiers in the fabrication of poly(vinyl alcohol) (PVA) membrane for the separation of an azeotropic mixture of tetrahydrofuran (THF) and water system. Poly(ethylene glycol) and anionic octa(tetramethyl ammonium)-functionalized POSS were used for this study. The membranes exhibited excellent water selectivity and permeance because of their preferential interactions toward water molecules in the azeotropic THF-water mixture. In the presence of poly(ethylene glycol)-POSS and anionic octa(tetramethyl ammonium)-POSS, the PVA membrane exhibited a significant increase in selectivity. A modified Maxwell-Stefan equation was used for the computation of the theoretical flux, which was compared with the experimental values. (c) 2018 Wiley Periodicals, Inc.