A silcone-silicalite-1 composite membrane was synthesized to recover acetone, butanol, and ethanol (ABE) from model solutions and the Clostridium acetobutylicum (ABE) fermentation broth. The adsorption capacity of the silicalite-l in the presence of a mixture of acetone, butanol and ethanol were 8-12, 85-90 and <5 mg/g, respectively. There was no apparent difference of absorption rate of butanol at 36 degrees C and 79 degrees C and desorption of butanol occurred efficiently at 78 degrees C and 1-3 Torr. The silicalite-l was characterized by chemical analysis, NMR, electron micrographs, surface area and pore size determination and found to have identical properties to other silicalite-l reported in the literature. The silicalite-l was incorporated into a silicone membrane in an effort to enhance butanol flux and selectivity. A membrane with a silicalite-l to polymer ratio of 1.5:1 (g:g) (306 mu m thick) had butanol selectivities of 100-108 and a flux of 89 g/m(2) h at feed butanol concentrations ranging from 5 to 9 g/l and a retentate temperature of 78 degrees C. A 170 mu m silicone membrane under identical conditions had selectivity and flux of 30 and 84 g/m(2) h, respectively. A thin silicalite membrane offered low selectivity and high flux, while a thick membrane offered high selectivity and low flux. The effect of butanol concentration (0.37-78 g/l) on flux and selectivity was also studied.