The ionic liquid(IL)1-ethyl-3-methylimidazolium dicyanamide([EMIM][DCA])was selected as an appropriate entrainer for the extractive distillation of the methanol-ethanol-water mixture.The COSMO-RS model was applied to screen out the appropriate solvents considering selectivity and solvent capacity together.Isobaric vapor-liquid equilibrium(VLE)experiments for the two systems of methanol-water and ethanol-water with different amounts of[EMIM][DCA]added were conducted at 101.3 kPa.The experimental data showed that[EMIM][DCA]exhibits an obvious salting effect for the methanol(or ethanol)-water mixture and eliminates the azeotropic point of ethanol-water.Moreover,the predicted values by UNIFAC-Lei model coincide well with experimental data.The separation mechanism was further explained in combination with surface charge density distribution(σ-profiles),excess enthalpy(HE),and binding energy.In addition,the flow charts were designed to evaluate the improvement of energy consumption with[EMIM][DCA]as the entrainer when compared to ethylene glycol(EG).The simulation results demonstrated that[EMIM][DCA]is more energy efficient than EG.
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