Liquid–liquid extraction of toluene from alkane with pyridinium based ionic liquid ([BPy][NO3] and [HPy][NO3]) at 298.15 K and atmospheric pressure

• Extraction of toluene from alkane with pyridinium based ionic liquid was studied.
• The ionic liquids [BPy][NO3] and [HPy][NO3] were used.
• The effect of alkane chain length on selectivity of toluene was evaluated.
• The effect of alkyl chain length of ionic liquids on toluene selectivity was investigated.
• The experimental data were correlated with the NRTL model.

The focus of this paper is to study the liquid−liquid extraction process for the separation of toluene from alkane employing the ionic liquids N-butylpyridinium nitrate, [BPy][NO3], and N-hexylpyridinium nitrate, [HPy][NO3], as a new solvents. New experimental data for the ternary systems of {[BPy][NO3] (1) + heptane, or octane, or decane (2) + toluene (3)} and {[HPy][NO3] (1) + heptane, or octane, or decane (2) + toluene (3)} at T = 298.15 K and atmospheric pressure are reported. The Othmer-Tobias and Hand correlation are examined to check the reliability of the experimental LLE data. The toluene distribution ratios and selectivity were calculated form the experimental data. The selectivity values are higher than unity which indicates the ILs, [BPy][NO3] and [HPy][NO3], used in this work are potential solvents to separate toluene from alkane. Besides, the effect of the alkane chain length in the selectivity values was evaluated. In addition, the result of the NRTL thermodynamic modeling shows, the experimental data were satisfactorily correlated.