Pervaporation of benzene/cyclohexane mixtures through aromatic polyamide membranes

A series of novel aromatic polyamides based on the 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (BAPPH) and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPPP) with various aromatic diacids were investigated for pervaporation separation of benzene/cyclohexane binary system. The aromatic polyamide membranes exhibited a benzene-permselectivity for all the feed compositions and the permeation rate increased with increasing benzene in the feed solution. The fluorine-containing polyamide membranes were swollen in benzene but only slightly in cyclohexane. A separation factor toward benzene, a permeation rate, and a pervaporation separation index (PSI) value through the fluorine-containing polyamide membrane (F-3) for a 50 wt.% feed benzene concentration were 4.0, 1470 and 5903 g m−2 h−1, respectively. The permeation rate and the PSI value of fluorine-containing polyamide membranes based on the BAPPH were higher than that of the aromatic polyamide membranes based on the BAPPP.