SEPARATION PROPERTIES OF WATER-ETHANOL MI XTURES BY ACRYLAMIDE-GEL POLYMERIZED IN PORES OF A THIN, POROUS CERAMIC MEMBRANE - EFFECTS OF PORE-SIZE OF CERAMIC MEMBRANE SUPPORTING GEL

Effects of the pore size of a thin, porous ceramic (silica-alumina) me mbrane supporting acrylamide gel on the separation properties of water /ethanol mixtures were investigated. The usefulness of repeating polym erization of gel reported in a previous paper(6)) were also examined. The pore size of the thin ceramic membrane, which was prepared by the sol-gel technique on a cylindrical substrate, was controlled by changi ng the particle size of alumina sol and the coating times of sol. The pore size distribution was evaluated from the permeation properties of humid air. Separation experiments were carried out by the pervaporati on method. Permeation properties of water/ethanol mixtures through acr ylamide gel are largely dependent on the pore size of the ceramic memb rane supporting the gel. This fact suggests that the pore size affects the thickness and shrinking properties of the gel polymerized in the pores. By repeating the polymerization of gel, the flux of ethanol dec reased dramatically. The gel polymerized in the small pores, however, cannot block the permeation of ethanol sufficiently. On the other hand , the flux of water increased or decreased depending on the pore size of the ceramic membrane. There exists an appropriate pore size for whi ch the promotion of water permeation occurs, as shown in the previous paper(6)). From these results, it can be said that appropriate selecti on of the pore size is important for the improvement of selective perm eation through this kind of composite membrane.