Isobaric Vapor-Liquid Equilibria for the Extractive Distillation of Ethanol plus Water Mixtures Using 1-Ethyl-3-methylimidazolium Dicyanamide

Isobaric vapor liquid equilibria (VLE) for the binary systems ethanol + 1-ethyl-3-methylimidazolium dicyanamide ([emim] [DCA]) and water + [emim] [DCA] as well as the VLE for the ternary system ethanol + water + [emim] [DCA] have been obtained at 100 kPa using a recirculating still. The effect of [emim] [DCA] on the ethanol + water system has been compared with that produced by another ionic liquid reported in the literature on the basis of the variation of solvent activity coefficients in ionic liquid (IL) + molecular solvent binary systems. From the results, [emim][DCA] appears as one of the best entrainers for the extractive distillation of the ethanol + water mixtures, causing the azeotrope to disappear at 100 kPa for ionic liquid mole fractions as low as 0.019. The experimental data were fitted with the Mock's electrolyte nonrandom two-liquid (NRTL) model, with a good agreement.