Preparation of Poly(dimethylsiloxane)-Polysulfone Composite Membrane by Sequential Absorption-Reaction-Evaporation Process and its Application in Treatment of Aqueous Solution Containing Volatile Organics

Preparation of composite poly(dimethylsiloxane)-polysulfone membrane by controlled cross-linking via sequential absorption-reaction-evaporation, is reported here. The top membrane layer of 0.5 mu m thickness exhibited the flux of 197 g center dot m(-2)center dot h(-1) with a separation factor of benzene over water (alpha(benzene/water)) and dichloromethane over water (alpha(dichloromethane/water)) as about 63 and 70, respectively, in a pervaporation separation from an aqueous feed of 150 ppm benzene and 250 ppm dichloromethane. The alpha values increased sharply by about seven- to ten-folds with increase in the membrane thickness from 0.5 to 10 mu m. Only a slight increase in the alpha values was observed with further increase in the membrane thickness from 10 to 82 mu m. The decrease in the flux with the increase in the membrane thickness was found to be exponentially related. Thus, the membranes of about 2 to 10 mu m thickness were optimal for the efficient removal of the organics from the aqueous feed. Comparison of the membranes prepared on different supports and other preparation technique are presented. SEM, AFM, and XRD were used for characterization of the membranes while viscosity and SANS measurements were performed for probing the initial solutions.