SORPTION AND PERVAPORATION SEPARATION OF ETHYL TERT-BUTYL ETHER AND ETHANOL MIXTURES THROUGH A BLENDED MEMBRANE

A new kind of membrane was prepared by blending poly( acrylic acid) wi th cellulose acetate propionate for the separation of ethyl tert-butyl ether and ethanol mixtures. The properties of the membranes were eval uated by the pervaporation separation of mixtures of ethyl tert-butyl ether/ethanol and the sorption experiments. The experimental results s howed that the selectivity and the fluxes of this membrane depend on t he blend composition and on that of processed feed mixtures. With resp ect to temperature, the ethanol fluxes obey the Arrhenius equation. Th e fluxes increase with the increase of the poly(acrylic acid) content in the blended membrane, the ethanol concentration in the feed, and th e experimental temperature. But the selectivity decreases as the poly( acrylic acid) content and the experimental temperature are raised up. When the feed composition is varied, this membrane shows the special c haracteristics at the azeotropic composition. In tile vicinity of th a zeotropic point, the minimum values of ethanol concentration in the pe rmeate and in sorption solution are obtained. The swelling ratios incr ease with an increase in tile temperature and the ethanol concentratio n. The ethanol concentration in the sorption solution is also influenc ed by the temperature and composition of the mixtures. When the temper ature increases, the sorption selectivity of the membrane decreases. ( C) 1997 John Wiley & Sons, Inc.