Pervaporation and Dialysis of Water-Ethanol Solutions Using Silicone Rubber Membranes

Abstract

Ethanol-water solutions may be concentrated by pervaporation through silicone rubber and regenerated cellulose film. Using silicone, separation factors (SF) decrease as the ethanol concentration in the feed solution increases (SF = 6.5 using 12.9 w/w% ethanol and 1.4 using 83.2% ethanol at 30°C). The temperature effect on separation factors is negligible, but is appreciable on permeation rates.

Ethanol permeation rates in the dialysis mode are not linear with ethanol chemical potentials in solution; silicone swelling coefficients also increase noticeably with alcohol concentration in aqueous solutions, indicating that preferential ethanol sorption occurs and is responsible for the separation.