Separation of benzene/cyclohexane mixture through supported liquid membranes with an ionic liquid

We separated a benzene/cyclohexane mixture through supported liquid membranes using ionic liquids, based on 1-alkyl-3-methylimidazorium and quaternary ammonium salts. It was found that benzene selectively permeated through the membranes against cyclohexane. We then studied the effects of the ionic liquids and the support polymer membranes on permeability and selectivity. The hydrophilic liquid membrane that used diethyl (2-methoxyethyl) ammonium tetrafloroborate as an ionic liquid and polyethersulfone as a support gave the highest selectivity, 47.1, which is comparable to the maximum value previously obtained by pervaporation. Three repetitive experiments for a 24 hour period show that the performance of the supported liquid membranes were retained. The results indicated that the application of a supported ionic liquid membrane to the benzene and cyclohexane separation process is promising.