Synthesis of highly selective copolymer membranes and their application for the dehydration of tetrahydrofuran by pervaporation

Acrylonitrile was copolymerized with 2-hydroxyethyl methacrylate (HEMA) at three different copolymer compositions by emulsion polymerization to produce polyacrylonitrile-2-hydroxyethyl methacrylate (PANHEMA) copolymer membranes containing increasing amounts of HEMA from PANHEMA-1 to PANHEMA-3. The dehydration of tetrahydrofuran (THF) over a concentration range of 0-14 wt % water in the feed was studied by pervaporation with these three copolymer membranes. The permeate water flux and separation factor for water was measured over the same concentration range at 30, 40, and 50°C. Among the copolymer membranes, PANHEMA-1 exhibited a reasonable water flux (34.9 g m ^-2 h^-1) with a very high water selectivity (264), whereas PANHEMA-3 showed a higher water flux (52 g m^-2 h^-1) but a lower water selectivity (176.5) for highly concentrated THF (0.56 wt % water in the feed) at 30°C. The permeation factors of water for all of the membranes were much greater than unity, which signified a strong positive coupling effect of THF on water permeation.