PERVAPORATION OF ALCOHOL TOLUENE MIXTURES THROUGH POLYMER BLEND MEMBRANES OF POLY(ACRYLIC ACID) AND POLY(VINYL ALCOHOL)

Homogeneous membranes were prepared by blending poly (acrylic acid) wi th poly (vinyl alcohol). These blend membranes were evaluated for the selective separation of alcohols from toluene by pervaporation. The fl ux and selectivity of the membranes were determined both as a function of the blend composition and of the feed mixture composition. The res ults showed that a polymer blending method could be very useful to dev elop new membranes with improved permselectivity. The pervaporation pr operties could be optimized by adjusting the blend composition. All th e blend membranes tested showed a decrease in flux with increasing pol y(vinyl alcohol) content for both methanol-toluene and ethanol-toluene liquid mixtures. The alcohols permeated preferentially through all te sted blend membranes, and the selectivity values increased with increa sing poly(vinyl alcohol) content. The pervaporation characteristics of the blend membranes were also strongly influenced by the feed mixture composition. The fluxes increased exponentially with increasing alcoh ol concentration in the feed mixtures, whereas the selectivities decre ased for both liquid mixtures.