SEPARATION OF A TOLUENE ETHANOL MIXTURE BY PERVAPORATION USING ACTIVECARBON-FILLED POLYMERIC MEMBRANES

In order to improve the separation properties of dense polymeric membr anes toward a toluene/ethanol mixture, various active carbons and two types of zeolites were introduced into a thin polymeric film in order to form a heterogeneous membrane composed of solid particles surrounde d by a polymer phase. Active carbons show a high adsorption selectivit y for an aromatic compound over ethanol in the low concentration range of the aromatic component. Sorption and pervaporation experiments wer e carried out with a toluene/ethanol mixture, and they showed no impro vement in selectivity and a decrease in flux for membranes filled with active carbons. For zeolite-filled membranes, both selectivity and fl ux decreased. A permeability model derived for heterogeneous systems w as used. It confirmed that the carbon particles have a closed porous s tructure, allowing no transport from one side to the other, and that t he zeolites have an ethanol selective permeation behavior.