Phase Equilibrium of Aqueous Glycine + Choline Chloride Ionic Liquid Solutions

Vapor–liquid equilibrium data (water activities and vapor pressures) for aqueous glycine + choline chloride ionic liquid (IL) mixtures and the corresponding binary aqueous IL solutions have been measured by the isopiestic method at 298.15 K and atmospheric pressure. The water activity data were accurately correlated with the segment-based local composition models of Wilson, NRTL and the modified NRTL. The solid–liquid equilibrium studies were also made on the above system, to determine the solubility of glycine in the presence of aqueous choline chloride, using refractive index measurements at various IL concentrations at 298.15 K. To describe the thermodynamic behavior of glycine in aqueous choline chloride solutions, transfer Gibbs energies (∆transferG) of the amino acid from water to aqueous IL solutions have been calculated from the above local composition models.