In this study, polyphenylmethylsiloxane (PPMS)-CA and polydimethylsiloxane (PI)MS)-CA membranes were prepared and used for the concentration of volatile organic compounds such as methanol, ethanol and acetone front aqueous solutions by pervaporation. The measurement of contact angles and swelling degree has indicated that the hydrophobicity of PPMS membranes is stronger than that of PDMS. Total fluxes for all three mixtures increase separately with increasing temperature while separation factors change little. Total fluxes also keep increasing with organic concentration. Separation factors of ethanol and methanol are nearly independent of feed concentration, but that of acetone/water mixture ascends sharply. PPMS membranes have better pervaporation performance than PDMS for acetone/water mixture. Total flux of acetone/water mixture by PPMS at 5 wt.% feed concentration and 40 degrees C is 2799 g m(-2) h(-1), and separation factor reaches 49.6. It can be attributed to the introduction of more hydrophobic and rigid phenyl groups. (C) 2007 Elsevier B.V. All rights reserved.