(Liquid + liquid) equilibrium of ternary and quaternary systems containing heptane, cyclohexane, toluene and the ionic liquid [EMim][N(CN)2]. Experimental data and correlation

• The ionic liquids [EMim][ N(CN)2] was proposed as solvent for the extraction of toluene from alkanes.
• The quaternary system {heptane + cyclohexane + toluene + [EMim][N(CN)2]} was determined.
• A purer toluene could be obtained in the presence of heptane than in the presence of both alkanes.
• Experimental LLE data were successfully correlated with the NRTL model.

In this work, the applicability of the ionic liquid [EMim][N(CN)2] as solvent for the (liquid + liquid) extraction of toluene from heptane and cyclohexane was ascertained. For that purpose, the (liquid + liquid) equilibrium (LLE) for the ternary systems {Heptane or Cyclohexane (1) + Toluene (2) + [EMim][N(CN)2] (3)} and the quaternary system {Heptane (1) + Cyclohexane (2) + Toluene (3) + [EMim][N(CN)2] (4)} was experimentally determined at T = 298.15 K and atmospheric pressure. Solute distribution ratios and the selectivities, derived from the experimental tie-lines, were used to determine if this ionic liquid can be used as potential solvent for the extraction of toluene from aliphatic hydrocarbons. Moreover, the LLE data obtained for the ternary systems were compared with those obtained for the quaternary system in order to study the influence of one or two aliphatic hydrocarbons on the extraction process. Comparisons with other ILs taken from literature were also carried out. Finally, the experimental LLE data for the investigated ternary and quaternary systems were correlated with the Non-Random Two Liquid thermodynamic model.