Yan Wang,Yucui Hou,Weize Wu,Dongdong Liu,Youan Ji,Shuhang Ren
As analogues of ionic liquids, deep eutectic solvents (DESs) have attracted considerable attention in the field of separating aromatics from aromatics/aliphatics mixtures. In this work, the performance of a series of DESs was evaluated for their selective extraction of toluene from toluene/n-heptane mixtures. The results showed that the extraction ability for toluene using DESs was greatly influenced by hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs) which formed the DESs. The selectivity of toluene was distinctly enhanced by short side chains, a small central atom of the cation and a large anion of the HBA, together with a suitable position for an alkyl chain and appropriate functional group of the HBD. It was also found that an increase of extraction temperature at the studied range could enhance the selectivity for toluene. This work makes the roles of HBAs and HBDs clear in the extraction of aromatics, providing information for designing more effective DESs for aromatics extraction.
In this work, the ability of ionic liquids (ILs) 1,3-dimethylimidazolium dimethylphosphate ([MMIM][DMP]), 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]), and 1-butyl-3-methylimidazolium dibutylphosphate ([BMIM][DBP]) as alternative solvents used in liquid removal of toluene from its combination with heptane was studied. The liquid–liquid equilibrium (LLE) data in relation to ternary systems {toluene + heptane + [MMIM][DMP], [EMIM][DEP], or [BMIM][DBP]} calibrated at T = 298.2 K and atmospheric pressure. The LLE results studied in relation to ternary systems were fitted by the thermodynamic nonrandom two-liquid (NRTL) model. The toluene solute distribution ratios and toluene/heptane selectivities, derived from the experimental LLE data, were compiled and analyzed to determine the extraction capacity of the studied ILs.