Separation properties of alcohol-water mixture through silicalite-I-filled silicone rubber membranes by pervaporation

The structure and the adsorption-desorption properties of zeolite silicalite-I by different treatments after synthesis were studied. The pervaporation properties of the alcohol-water mixture through silicone rubber filled with zeolite silicalite-I by different treatments were also investigated. Treating silicalite-I by acid or/and under steam was found to eliminate the metallic impurities in the zeolite and to perfect the crystalline :structure of the zeolite. After treatment, silicalite-I is more selective to alcohol and the desorption of the alcohol from the zeolite is also easier. The silicone rubber membrane filled with treated silicalite-I shows a high performance for alcohol extraction from the dilute aqueous solution by pervaporation. The separation factor of the poly(dimethyl siloxane) (PDMS) membrane filled with silicalite-I treated successively by acid and steam is about 30 when the ethanol content in the feed is 5 wt % at 50 degrees C. (C) 1998 John Wiley & Sons, Inc.