Liquid-Liquid Equilibrium Studies on the Removal of Thiophene and Pyridine from Pentane Using Imidazolium-Based Ionic Liquids

1-Ethyl-3-methylimidazolium-based ionic liquid with acetate [OAc], ethylsulfate [EtSO4], and methyl sulfonate [MeSO3] anions was used to generate the liquid liquid equilibrium (LLE) data for the quaternary mixture of IL (1)-thiophene (2)-pyridine (3)-pentane (4). The selectivity and distribution coefficient values were calculated to evaluate the effectiveness of the simultaneous extraction of thiophene and pyridine from pentane at ambient conditions. The experimental tie-line data were successfully validated by the nonrandom two liquid (NRTL) and universal quasi-chemical (UNIQUAC) models, giving root mean square deviation (RMSD) values less than 1 % for all the systems. The novelty of the work was that a conductor like screening model for real solvents (COSMO-RS) model was used to predict compositions of quaternary systems. However, it failed to reproduce the slope of the tie-lines at high solute concentration, especially for the ionic liquid rich phase. The COSMO-RS predictions gave a RMSD of 4.62 % ([EMIM][OAc]), 5.3 % ([EMIM][EtSO4]), and 6.07 % ([EMIM][MeSO3]).