Pervaporation separation of water-ethanol mixtures using metal-ion-exchanged poly(vinyl alcohol) (PVA)/sulfosuccinic acid (SSA) membranes

Poly(vinyl alcohol)/sulfosuccinic acid (PVA/SSA) membranes in the hydrogen form were converted to monovalent metal ion forms Li+, Na+, and K+. The effect of exchange with metal ions was investigated by measuring the swelling of water-ethanol (10/90) mixtures at 30 degreesC and by the pervaporative dehydration performance test for aqueous ethanol solutions with various ethanol concentrations at 30, 40, and 50 degreesC. In addition, electron spectroscopy for chemical analysis (ESCA) analysis was carried out to study the quantity of metal ions in membranes. From the ESCA analysis, the lithium ion quantity in the resulting membranes is greater than that of any other metal ions in question because of the easy diffusion of a smaller metal ion into the membrane matrix. The swelling ratio was in the following order: PVA/SSA-Li+ > PVA/SSA-Na+ > PVA/SSA-K+ membranes. For pervaporation, the PVA/SSA-Na+ membrane showed the lowest flux and highest separation factor for all aqueous ethanol solutions. (C) 2002 Wiley Periodicals, Inc.