Pervaporation separation of methanol/methyl tert‐butyl ether with poly(lactic acid) membranes

Poly(lactic acid), as a natural source polymer, was used to prepare pervaporation dense membranes. The performance of these membranes for the separation of the methanol (MeOH)/methyl tert‐butyl ether (MTBE) mixtures was investigated. The effects of different operating conditions, including the feed concentration of MeOH, temperature, and flow rate, were examined. Several characterization tests were performed as well. The swelling results, scanning electron microscopy images, contact angles, and mechanical strength measurements are presented. These membranes were found to be selective to MeOH, particularly for traces of MeOH in MTBE with a separation factor of more than 30. There was a small decrease in the separation factor when the feed temperature was increased; meanwhile, the total flux increased to some extent. This could be explained with respect to the thermal motions of the polymer chains and the permeating molecules. With an increase in the feed flow rate, both the selectivity and total flux increased because the concentration and temperature polarizations decreased. At higher flow rates, the feed components were homogeneously distributed over the membrane surface, whereas there may have been a concentration or temperature gradient at lower flow rates. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010