Abstract
In this work, we have studied the liquid–liquid extraction of toluene from toluene/n–heptane mixtures with 10 % of toluene in mass basis at 313.2 K and atmospheric pressure using 1-ethyl-3-methylimidazolium thiocyanate ([emim][SCN]) ionic liquid (IL) as extraction solvent. Also, we have employed as extraction solvents binary mixtures of [emim][SCN] with AgBF4, AgNO3, Co(SCN)2, CuSCN, and AgSCN in a transition metal salt concentration of 0.5 M, to evaluate the influence of adding metal salts to the IL on the extraction efficiency. To perform a comparative analysis of extractive properties of the IL-based solvents and those of sulfolane, toluene distribution ratios and toluene/n-heptane selectivities were calculated from the liquid-liquid equilibrium (LLE) data. Dynamic viscosities of the solvents were also measured at the temperature range from 293.2 to 353.2 K. Pure [emim][SCN] IL could be considered as an alternative to organic solvents, since this IL has shown adequate physical and extractive properties. By contrast, salt addition caused an important increase in the dynamic viscosity of the IL, and the extractive properties of these mixtures were quite similar to the results obtained with pure [emim][SCN].
