Liquid–liquid extraction of toluene from heptane by {[4bmpy][Tf2N] + [emim][CHF2CF2SO3]} ionic liquid mixed solvents

Extraction of toluene from heptane at T = 313.2 K and atmospheric pressure using a mixed solvent composed of the ionic liquids 1-butyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide ([4bmpy][Tf2N]) and 1-ethyl-3-methylimidazolium 1,1,2,2-tetrafluoroethanesulfonate ([emim][CHF2CF2SO3]) has been considered in this study. The results show that for a mole fraction of 0.3 for [4bmpy][Tf2N] the values of the capacity of extraction of toluene and the selectivity of the mixed solvent are higher than those of sulfolane for the whole range of compositions, taken this organic solvent as a benchmark. Therefore, this mixture of ILs could be an alternative to sulfolane in the liquid–liquid extraction of toluene from heptane.

► Binary mixtures of ionic liquids as extraction solvents of aromatics.
► Combination of ionic liquids with complementary extraction properties.
► [4bmpy][Tf2N] shows higher capacity but lower selectivity than sulfolane.
► [emim][CHF2CF2SO3] shows lower capacity but higher selectivity than sulfolane.
► Mixed {[4bmpy][Tf2N] + [emim][CHF2CF2SO3]} improves both extractive properties.