Concentration of ionic liquids from aqueous ionic liquids solution using electrodialyzer

Ionic liquids (ILs) have great potential for industrial use as green alternative solvents. However, the high price of ILs restricts their applications. Since ILs are easily lost in its application process, it is necessary to seek for an effective approach to recover and concentrate ILs from ILs/water mixtures. In this paper, an electrodialysis (ED) process was proposed to concentrate the model ionic liquids of 1-butyl-3-methylimidazolium chloride ([BMIM]Cl). It was demonstrated that ILs could be successfully concentrated from aqueous ILs solution using the permselectivity of ion exchanges membranes under DC electric field. The structure of the products was identified with H-1 NMR. The effects of applied voltage and flow rate were intensively investigated. The experimental results showed that the increase in applied voltage and the decrease in flow rate would lead to the better performance of ED cell.