(144f) Surface Energies of Poly(Vinyl Alcohol) Membranes for Pervaporation

Surface energies of hydrophilic poly(vinyl alcohol) PVA membranes for pervaporation were determined using contact angle measurements. PVA membranes were synthesized and then crosslinked by heat treatment at 125 deg C and by chemical reaction with glutaraldehyde at room temperature. The advancing contact angles were measured on the membrane surface over a period of time using sessile drop technique. The crosslinking reactions of the hydrophilic membranes were characterized by IR spectroscopy. Results from the contact angle experiments show that the contact angle increases with increasing glutaraldehyde concentration in crosslinking reactions. Surface energies were calculated by assuming adsorption of the permeate molecules on the feed side of the membrane. The pervaporation separation of ethanol water-mixtures was performed over a range of 10-70 wt% ethanol in the feed at temperatures varying from 25-60 deg C. Dehydration experiments using the PVA membranes show that the flux decreases but selectivity increases for the crosslinked membranes. The synthesized membranes were ranked depending on their total fluxes and surface energies.