Application of 1-hexyl-3-methylimidazolium trifluoromethanesulfonate to the removal of alcohol from mixtures with heptane

An ionic liquid (IL) of 1-Hexyl-3-methylimidazolium trifluoromethanesulfonate [Hmim][OTf] was investigated as a possible extraction solvent in petrochemical processes for the removal of alcohol from an azeotropic mixture with heptane. Liquid-liquid equilibrium (LLE) experiments of three ternary systems, hexane + ethanol, 1-propanol, or 2-propanol + [Hmim][OTf], were conducted at 298.15 K and atmospheric pressure. The efficiency of [Hmim][OTf] as an extraction solvent was determined by calculating the solute distribution ratio, β, and selectivity, S, and this efficiency was compared to other ionic liquids from the literature. The structural volume (r) and surface area (q) of [Hmim][OTf] were determined using a quantum chemistry approach. The LLE data of the three ternary systems were correlated using NRTL and UNIQUAC models, and the UNIFAC model was used to predict the phase behavior compared to the experimental data.