Performances of poly (vinylpyrrolidone-co-vinyl acetate)-cellulose acetate blend membranes in the pervaporation of ethanol-ehyl tert-butyl ether mixtures - Simplified model for flux prediction

High performance pervaporation membranes for the selective removal of ethanol from ethyl t-butyl ether (ETBE) were prepared by blending cellulose acetate with poly (vinylpyrrolidone-co-vinyl acetate) in different proportions and studied in sorption and pervaporation of ethanol-ETBE mixtures of compositions ranging from 5 to 25 wt% ethanol. The membrane performances are improved when the copolymer content is higher due to strong flux enhancement. Both the ethanol and ETBE amounts sorbed by the membranes increase with the ethanol content in the mixture with which the membranes are in equilibrium, but that of ethanol is one order of magnitude higher than that of ETBE; this indicates an enhancement of ETBE sorption due to the interactions with ethanol sorbed by the membrane. We observed a similar behavior for the ethanol and ETBE fluxes. A simplified model with an ethanol flux increasing exponentially, and an ETBE flux increasing linearly with the ethanol content at the membrane upstream face, was developed and validated with the experimental data. (C) 1998 Elsevier Science B.V.