CONCENTRATION OF DILUTE ACETONE WATER SOLUTIONS USING PERVAPORATION

The separation of acetone-water mixtures by pervaporation has been studied. Four membranes were evaluated: a silicone composite (SC) membrane, a polydimethylsiloxane (PDMS) membrane, a polymethoxysiloxane (PMS), and a poly ether-block-polyamide copolymer (PEBA) membrane. The silicone composite membrane exhibited a higher flux and selectivity than any of the other membranes studied. At a feed temperature of 50-degrees-C, a permeate-side pressure of 1 torr, and a feed concentration of 5.0%, the silicone composite membrane had a flux of 1.1 kg/m2.h and a selectivity of 50. The effects of temperature and permeate-side pressure on membrane transport were studied using the SC membrane. An increase in temperature increased the flux exponentially, but had little effect on selectivity. An analysis of the data shows that the trend agrees quite well with an Arrhenius-type relationship. As the permeate-side pressure increased, the flux decreased in a sigmoidal fashion over the range evaluated. Selectivity did not change significantly over the lower portion of the pressure range studied. The effect of feed concentration on flux and selectivity was also investigated.