Pervaporation of benzene/cyclohexane mixtures through aromatic polyamide membranes

A series of novel aromatic polyamides based on the 2,2-bis[4-(4-aminophenox y)phenyl]hexafluoropropane (BAPPH) and 2,2-bis[4-(4-aminophenoxy)phenyl]pro pane (BAPPP) with various aromatic diacids were investigated for pervaporat ion separation of benzene/cyclohexane binary system. The aromatic polyamide membranes exhibited a benzene-permselectivity for all the feed composition s and the permeation rate increased with increasing benzene in the feed sol ution. The fluorine-containing polyamide membranes were swollen in benzene but only slightly in cyclohexane. A separation factor toward benzene, a per meation rate, and a pervaporation separation index (PSI) value through the fluorine-containing polyamide membrane (F-3) for a 50 wt.% feed benzene con centration were 4.0, 1470 and 5903 g m(-2) h(-1), respectively. The permeat ion rate and the PSI value of fluorine-containing polyamide membranes based on the BAPPH were higher than that of the aromatic polyamide membranes bas ed on the BAPPP. (C) 2001 Elsevier Science B.V. All rights reserved.