Liquid-Liquid Extraction of Toluene from Heptane Using [EMIM][NTF2] Ionic Liquid: Experimental and Extensive Thermodynamics Study

The performance of the ionic liquid (1-ethyl-3methylimidazolium bis (trifluoromethylsulfonyl)imide, [EMIM][NTF2]) as a green, non-aqueous and hydrophobic solvent and sulfolane as a conventional solvent for liquid-liquid extraction of toluene from its mixture with heptane was investigated. The LLE phase behavior was predicted with the help of the UNIFAC as a predictive thermodynamic model. The interfacial tension of the studied systems was measured to investigate the effect of the dissolved toluene concentration on interfacial tension. It was revealed that the average selectivity of the systems with IL (316.752) is much higher than the systems containing sulfolane (18.661) under similar experimental conditions. For low mass fractions of toluene less than 0.4, the performance of the IL is better, whereas, for high toluene mass fractions more than 0.4, sulfolane exhibits superior performance.