A ZSM-5 filled polydimethylsiloxane membrane with 44.4 wt.% zeolite loading was used in the pervaporative removal of 1-butanol from its mixtures with 1-butanol. A small quantity of ethanol was added to the feed as a by-product to test the response of the membrane. It was found that the permeation behaviour of other feed components was changed and membrane selectivity decreased. This change was attributed to the frequently-observed inter-component coupled transport in multi-component feed systems. The impact of ethanol on recovery of 2,3-butanediol was evaluated using a simulated continuous operation, which enriched 2,3-butanediol to 99.5 wt.% from a feed containing 5 wt.% 2,3-butanediol and less than 1.0 wt.% ethanol. It was observed that membrane selectivity improves as ethanol concentration decreases in the stream due to its preferential removal. The final recovery of 2,3-butanediol was not significantly reduced as the concentration of ethanol was below 1.0 wt.%. (c) 2011 Canadian Society for Chemical Engineering