Pervaporative dehydration of dimethyl formamide (DMF) by crosslinked copolymer membranes

Three different copolymers of acrylamide (AM) with increasing amounts of 2-hydroxyethyl methacrylate (HEMA), i.e., PAMHEMA-1, PAMHEMA-2, and PAMHEMA-3, were synthesized and the crosslinked (gelled) copolymer membranes that were made from these sol copolymer solutions (uncrosslinked) were used for pervaporative dehydration of dimethyl formamide (DMF) over the concentration range of 0-13.07 wt % water in feed. These hydrophilic gel copolymer membranes were found to be highly water-selective in both sorption and diffusion through the membranes. The water flux was found to decrease with an increasing degree of crosslinking from PAMHEMA-1 to PAMHEMA-3 membranes. Among the three membranes, the PAMHEMA-3 membrane showed the highest separation factor (464.3) and reasonable flux (23.91 g/(m² h) for 0.5 wt % of water in the feed) for water, whereas the maximum water flux with high separation factor was exhibited by the PAMHEMA-1 membrane (47.45 g/(m² h) and 263.8 for 0.5 wt % of water in the feed) at 30 °C. When the pervaporation (PV) experiment was performed at 50 °C, the flux was observed to increase manifold with little change in the separation factor (51.03 g/(m² h) and 369.6 for 0.5 wt % of water in the feed for the PAMHEMA-3 membrane).