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The copolymer of acrylic acid and acrylonitrile has been synthesized and pervaporation properties of the copolymeric membranes have been investigated. In order to elucidate the influence of membrane-permeate interaction on the pervaporation of water-ethanol mixtures and to prepare much improved membranes

the membranes have been treated with alkali metal

alkali earth metal and transition metal salt aqueous solutions. The treated membranes （ionized membranes） exhibited higher separation factors than the untreated membranes. The separation factors of various alkali metal cation membranes decreased in the following order : Li

+

>

Na

+

>

K

+

and the permeation rates showed an opposite tendency. The dependence of pervaporation behavior on the copolymer composition

feed concentration and operating temperature have been studied with both ionized and non-ionized membranes. The apparent activation energies of water and ethanol permeation were calculated.