Liquid-liquid measurement and correlation for separation of azeotrope (dimethyl carbonate and ethanol) with different imidazolium-based ionic liquids

For separating the azeotrope of dimethyl carbonate (DMC) and ethanol, four imidazolium-based ionic liquids were selected as extractants. The liquid-liquid equilibrium data for the ternary systems DMC + ethanol + ILs were determined at 298.15 K under pressure of 101.3 kPa. The effect of ILs anions and the alkyl chain length of the cations on the liquid-liquid phase behavior was investigated and discussed. Moreover, the distribution coefficient and selectivity were calculated and analyzed to evaluate the most suitable IL to separate the azeotrope of DMC and ethanol. Meanwhile, the interaction energies of ILs with DMC and ethanol were explored. The calculated results indicate that the adopted ILs have strong interactions with ethanol than with DMC. In addition, the NRTL activity coefficient model was adopted to correlate the measured experimental data and the optimum binary interaction parameters were obtained.