Liquid Extraction of Toluene from Heptane, Octane, or Nonane Using Mixed Ionic Solvents of 1-Ethyl-3-methylimidazolium Methylsulfate and 1-Hexyl-3-methylimidazolium Hexafluorophosphate

Liquid liquid extractions of toluene from paraffin compounds, using binary ionic solvent mixtures of 1-hexyl-3methylimidazolium hexafluorophosphate [hmim][PF6] and 1-ethyl-3-methylimidazolium methylsulfate [emim] [CH3SO4], have been examined at 313.15 K and an atmospheric pressure of 101 kPa. Based on the experimental liquid liquid equilibrium data for the pseudoternary systems consisting of heptane, octane, or nonane + toluene + [hmim] [PF6] + [emim] [CH3SO4], the distribution ratios and selectivity values were calculated and compared to systems using pure ionic liquids or sulfolane. The results showed that the use of a binary mixture of [hmim] [PF6] + [emim] [CH3SO4] at a solvent mole fraction of 0.9 for [hmim] [PF6] improves both the toluene distribution ratio and the selectivity, with respect to those of sulfolane and other pure ionic solvents. Consequently, these mixed ionic liquids could be considered an environmentally benign alternative solvent for the aromatic extraction process. The experimental data were correlated by the nonrandom two-liquid (NRTL) model.