Characteristics of permeation and separation of aqueous alcohol solutions through hydrophobic polymer membranes

Abstract

Characteristics of the permeation and separation of aqueous alcohol solutions through hydrophobic polymer membranes, such as polystyrene and poly(vinyl chloride), were studied under various conditions by pervaporation and 'evapomeation' techniques. These hydrophobic membranes predominantly permeated water molecules from aqueous alcohol solutions in both pervaporation and evapomeation methods. Permeation rates in evapomeation were approximately equal to those in pervaporation, but the separation factors in the former were greater than those in the latter method. The permeation rate decreased and the separation factor increased as the alcohol molecule in aqueous solution increased in size. When the temperature of the feed vapour in evapomeation was raised, both permeation rate and separation factor were increased. Mechanisms for permeation and separation of aqueous alcohol solutions through hydrophobic polymer membranes by pervaporation and evapomeation techniques are discussed from physicochemical viewpoints.