Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

The mixture of acetonitrile (1) + n-propanol (2) forms a binary azeotropic mixture at atmospheric pressure which cannot be separated by common distillation. In this paper, the ionic liquids (ILs) 1,3-dimethylimidazolium dimethylphosphate ([MMIM][DMP]) and 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]) were used as solvents for separating the binary azeotropic mixture. The ternary isobaric vapor-liquid equilibrium data of acetonitrile (1) + n-propanol (2) + ILs (3) at atmospheric pressure in three ILs mole fractions of 0.048, 0.091 and 0.131 were obtained. The results showed that the addition of [MMIM][DMP] or [EMIM][DEP] could enhance the relative volatility of acetonitrile to n-propanol, and the azeotropic point of the binary azeotropic system could disappear at the mole fractions of ILs above mentioned. The effect of separation of ILs was in the order of [EMIM][DEP] greater than [MMIM][DMP]. The interaction parameters were obtained by fitting the nonrandom two-liquid (NRTL) model to the binary vapor-liquid equilibrium experimental data. The predicted results obtained using NRTL model were in good agreement with experimental data. In addition, a quantum chemical calculation based on Gaussian 09 at the B3LYP/6-311++G** level were also conducted. The calculated results indicated that the molecules of ILs had stronger interaction to n-propanol molecule than acetonitrile one.