Studies on syntheses and permeabilities of special polymer membranes, 70. Permeation and separation characteristics for aqueous alcoholic solutions by evapomeation and pervaporation through polystyrene membranes

Abstract

AbstractPermeation and separation characteristics of methanol/water and ethanol/water mixtures by evapomeation and pervaporation through unelongated and biaxially elongated polystyrene membranes were investigated under various conditions. All polystyrene membranes predominantly permeated water molecules in both methods. Permeation rates in the case of evapomeation were smaller than those of pervaporation, but the separation factors in the former case were greater than those in the latter. The separation factors through the biaxially elongated polystyrene membrane were larger than those of the unelongated polystyrene membrane, this value being ca. 1500 for an azeotropic mixture of ethanol/water. Permeation and separation mechanisms through these polystyrene membranes involved in both membrane separation techniques are discussed from the viewpoints of solution‐diffusion of permeating molecules and of the membrane structure.