Pervaporation separation of benzene/cyclohexane through AAOM-ionic liquids/polyurethane membranes

Supported ionic liquids/polyurethane (PU) membranes were prepared by immobilizing ionic liquids on a porous anodic aluminum oxide membrane (AAOM) support that was coated on one side with polyurethane (PU). The microstructure of all membranes was characterized using scanning electron microscopy (SEM). The pervaporation separation performance of the supported ionic liquids/polyurethane membranes was investigated for benzene/cyclohexane (Bz/Cy) mixtures. The SEM results demonstrated that the porous surface of the AAOM support was sealed by the dense polyurethane membrane and the pores of the AAOM support were impregnate with ionic liquids. The ionic liquids filling in the AAOM support enhanced the separation selectivity of Bz/Cy. The separation factor of Bz to Cy increased from 5 to 34.4 and the largest PSI of AAOM-[C4mim]PF6/PU membrane reached 452.54 g m−2 h−1 at 55 °C for a 50 wt.% Bz/Cy mixture. Because the polyurethane prevented the leakage of ionic liquids filled in the AAOM support, the supported ionic liquids/polyurethane membranes exhibited excellent stability.