Study of fluorosilicone rubber membrane for pervaporation.

Abstract

Homogeneous fluorosilicone rubber membranes were prepared to study the dehydration of isopropyl alcohol by pervaporation. The membranes were either water-selective or isopropyl alcohol-selective, depending on the feed composition. The azeotropic composition of isopropyl alcohol-water system predicted using Margules Equation occurred at 41 mole% of water. However, the feed and permeate compositions were found to be equal in pervaporation experiments when the water content in the feed was approximately 70 mole%. Generally, water-selectivity was enhanced by pervaporation as compared to liquid-vapor equilibrium. Composite membranes were also prepared with a thin layer of fluorosilicone rubber coated on top of a porous substrate polyethersulfone membrane. It was found that the performance of the composite membrane was affected by the molecular weight of polyethersulfone used to prepare the porous substrate. The performance of composite membrane became more consistent as the molecular weight of polyethersulfone became more uniform. The membrane selectivity increased with a decrease in the mean pore size.