Silicalite-1 membranes supported on porous alpha-Al2O3 supports were developed and used for pervaporation separation of acetic acid/water mixtures. The effects of the amount of deposited seed crystals on the alpha-Al2O3 support and the H2O/SiO2 ratio in the synthesis solution on the pervaporation separation performance of the membranes were investigated. Seed layers on the alpha-Al2O3 support suppressed Al atom leaching from the a alpha-Al2O3 support during the hydrothermal treatment, resulting in improved membrane performance. The membrane prepared using a seed amount of ca. 5 g/m(2) and a H2O/SiO2 ratio of 75, with the thickness of zeolite layer equal to ca. 9 mu m, exhibited relatively high selectivities for ethanol/water and acetic acid/water mixtures. The total fluxes of the membrane were 0.47 and 0.04 kg/(m(2) h) toward 10 wt.% ethanol/water and 5 wt.% acetic acid/water mixtures, respectively and the corresponding separation factors were 88 and 33, respectively. For acetic acid/water mixtures, the silicalite-1 membranes prepared in this study exhibited a separation factor greater than those of any membranes previously reported, and a close correlation between the separation selectivity of ethanol for ethanol/water mixtures and that of acetic acid for acetic acid/water mixtures was revealed; i.e., the separation factor of acetic acid was equal to one-fourth of that of ethanol in organic/water mixtures of the same concentration. (C) 2016 Elsevier B.V. All rights reserved.