Plasma‐modified poly(vinyl alcohol) membranes for the dehydrationof ethanol

Non‐porous poly(vinyl alcohol) (PVA) membranes prepared by a cast‐evaporating technique were covered with an allyl alcohol or acrylic acid plasma‐polymerized layer. The wettability and the surface energy, as well as the chemical nature of the deposit, were assigned by X‐ray photoelectron spectroscopy (XPS) and Fourier‐transform infrared spectroscopy (FTIR). The ability of the modified membranes for dehydrating the water/ethanol azeotropic mixture by pervaporation was studied at 25, 40 and 60 °C. The best selectivity (α = 250 at 25 °C) was obtained in the case of the allyl alcohol plasma treatment. The results obtained are discussed on the basis of the hydrophilicity as well as in terms of the weakly crosslinked superficial layer that favoured the membrane swelling. Copyright © 2003 Society of Chemical Industry