Measurement and Prediction of Excess Enthalpies for Ternary Solutions 1‑Ethyl-3-methylimidazolium Dimethylphosphate + Methanol or Ethanol + Water at 298.15 K and at Normal Atmospheric Pressure

Abstract

The excess enthalpies of binary and ternary solutions composed of ionic liquid, 1-ethyl-3-methylimidazolium dimethylphosphate [Emim]­[DMP], water, and methanol (or ethanol) were measured with an adiabatic calorimeter at 298.15 K and under normal atmospheric pressure. The experimental data for three sets of binary solution [Emim] [DMP] (1) + H₂O­(2)/CH₃OH­(2)/C₂H₅OH­(2) were correlated with the Gibbs–Helmholtz, the nonrandom two liquid (NRTL), and the universal quasi-chemical (UNIQUAC) equations. The binary interaction parameters in the NRTL and UNIQUAC models were obtained and used to predict excess enthalpies of ternary solutions [Emim] [DMP](1) + CH₃OH­(2) or C₂H₅OH­(2) + H₂O­(3). The results show that the excess enthalpies of ternary solutions are negative across the whole range of concentrations, which indicates that the [Emim] [DMP] mixed with H₂O, CH₃OH, or C₂H₅OH is exothermic. Meanwhile, the average relative deviations (ARD) between the experimental and correlated excess enthalpies for the three sets of binary solutions are 2.49 %, 1.64 %, 2.44 % (NRTL) or 2.98 %, 3.00 %, and 3.43 % (UNIQUAC). The ARD between the experimental and predicted excess enthalpies for two set of ternary solution are 7.89 %, 5.17 % (NRTL) and 1.86 %, and 1.86 % (UNIQUAC), respectively