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The experimental liquid – liquid equilibrium (LLE) data for three ternary mixtures containing an ionic liquid (IL) (1-butyl-3-methyl imidazolium thiocyanate [Bmim][SCN]), alkanes ( n -hexane, n -octane and n -decane) and sulfur compound (thiophene) have been measured experimentally. Distribution and selectivity coefficients have been calculated using experimental data. The LLE data have been obtained at 25 °C and ambient pressure. The experimental LLE data of ternary mixtures have been compared with our previous works. It has been shown that the IL with higher molecular weight of cation has higher solute distribution and lower selectivity coefficients. It has been found that the solubility decreases as the cation length decreases, meanwhile ILs cation chain length has a remarkable effect on solubility of alkanes. Moreover, the experimental data have been demonstrated that the selectivity decreases as alkane chain length of alkane decreases while the solubility of alkanes in the ILs increases, hence the removal costs of aromatic sulfur components will be increased. The results show that [Bmim][SCN] has the lowest alkane solubility and highest selectivity coefficient, in the system containing n -decane and thiophene. A comparative study reveals that compared to other ILs, [Bmim][SCN] is a more suitable solvent. Finally, the experimental data have been correlated utilizing non-randomness two liquid (NRTL) model. The binary energy parameters were obtained, it can be seen that the model can correlate the experimental data efficiently. [ABSTRACT FROM AUTHOR]

Ionic Liquids (IL's) are now considered as useful alternative solvent for the desulfurization of gasoline and diesel oils by liquid–liquid extraction. In this work, 1-hexyl-3-methylimidazolium thiocyanate([Hmim][SCN]) and 1-octyl-3-methylimidazolium thiocyanate([Omim][SCN]) as ionic liquids were investigated as model solvents for removal of thiophene from some aliphatic hydrocarbons ( n -hexane, n -octane and n -decane) as fuel model. Liquid–liquid phase equilibrium data were measured for ternary systems containing one ionic liquid as solvent, thiophene as sulfur component and one aliphatic hydrocarbon as fuel model at 298.15 K under ambient pressure. It was found that the IL with lower molecular weight of cation has higher selectivity but lower solute distribution coefficients. Besides, the experimental data demonstrates that the selectivity increases as alkane chain length of fuel model increases while the solubility of ionic liquids decreases, hence the costs of desulfurization process will be decreased. Our results show that for the case of [Hmim][SCN](1) + n -decane(2) + thiophene(3) the highest selectivity and lowest alkane solubility were obtained. In other words [Hmim][SCN] is a more suitable solvent than [Omim][SCN] for desulfurization of higher alkane. Finally in order to find the model parameters, the nonrandom two liquid (NRTL) was used to correlate the experimental data. The results show the model can successfully correlate the experimental data. [ABSTRACT FROM AUTHOR]

[Display omitted] • Extraction of dibenzothiophene was investigated from model fuel (n-octane). • Two different Deep Eutectic Solvents were synthesized and used as extractive agents. • The structures of Deep Eutectic Solvents were confirmed by FTIR and H-NMR analyses. • Liquid-liquid equilibrium was modeled by the NRTL model. Among the most important causes of air pollution we may refer to hydrocarbon fuels with a large content of organosulfur compounds. These compounds must be removed to the level of standard concentration for which different techniques are commonly in use. Since, desulfurization of aromatic sulfur compounds, such as thiophenes, is not possible by common methods such as hydrodesulfurization, other methods should be considered. In recent years, scientists have focused on extractive desulfurization using Deep Eutectic Solvents (DES) as a new method for removing organosulfurs from hydrocarbon fuels. In this research, two new DESs are synthesized. As the model fuel, we used n-octane, and dibenzothiophene (DBT) was chosen as the organosulfur content with a 1000 ppm concentration. DESs were synthesized by mixing quaternary ammonium salts and trifluoroacetic acid in a heating method. The structures of DESs were confirmed by FTIR and H-NMR analyses. The extraction process was first carried out at temperatures ranging from 25 to 40 °C. The results showed that the best temperature was 35 °C. Then, the effect of fuel to DES mass ratio (i.e. different compositions of feed), on extraction efficiency was examined. For thermodynamic modeling of liquid–liquid equilibrium the Non Random Two Liquid (NRTL) activity coefficient model was implemented. The parameters of the NRTL model were correlated using the binary data obtained from solubility experiments. Finally, the adjusted parameters were used for predicting ternary phase equilibrium data obtained in this work. The root mean square deviation from experimental data was less than 0.11% for each solvent. [ABSTRACT FROM AUTHOR]