SELECTIVE SEPARATION OF WATER FROM AQUEOUS ALCOHOL SOLUTION THROUGH FLUORINE-CONTAINING AROMATIC POLYAMIDE MEMBRANES BY PERVAPORATION

For dehydrating aqueous alcohol solution by pervaporation, a fluorine- containing aromatic polyamide membrane was synthesized. The fluorine-c ontaining polyamides were prepared by direct polycondensation of ,2-bi s[4-(4-aminophenoxy)phenyl]hexafluoropropane, BAPPH, with various arom atic diacids by triphenyl phosphite and pyridine in N-methyl-2-pyrroli dinone. The novel aromatic polyamides were examined by elemental analy sis, FTIR, and X-ray diffraction. The aromatic polyamides were crystal line except (A-B-2). The effects of feed composition, degree of swelli ng, and the molecular size of alcohols on pervaporation performances w ere investigated. Water molecules preferentially permeate through the aromatic polyamide membranes. A separation for water of 36 and a 383 g /m(2)h permeation rate with a 90 wt% feed ethanol concentration was ob tained.