Pervaporation of Ethanol From Dilute Aqueous Solutions Through Silicalite-1/Polydimethylsiloxane Nanocomposite Membranes

The production and distribution of energy is a foundation of modern society and is integral to the global economy for transportation, industrial processes, and residential and commercial uses. Among the wide range of potential renewable energy sources (wind, wave, solar), biologically derived fuels are a promising alternative to liquid fossil fuel. Pervaporation is a process with great potential for continuous extraction of alcohols from biological fermentation broths.

Here, we report on the synthesis and pervaporation performance of silicalite-1/polydimethylsiloxane (PDMS) nanocomposite membranes.  We fabricated 20-50 micron thick PDMS films on porous alumina supports via dip-coating.  Then, we created nanocomposite membranes by incorporating 100 nm diameter silicalite-1nanoparticles into the casting solutions (at loadings of 10, 20, and 30 weight percent).  Using a batch pervaporation system, we measured flux and selectivity of the membranes for solutions of 4 wt% ethanol in water at 24 °C, 50 °C, and 65 °C. With increased zeolite loadings in the nanocomposite membranes, we obtained both increased flux and increased alcohol selectivity.  We also report on a variety of characterizations of the nanocomposite membrane chemical structure and morphology.