Thermodynamic and Transport Properties of Lithium Bromide in Aqueous Solutions of Protic Ionic Liquids Based on 2-Hydroxyethylammonium Propionate at Different Temperatures

The protic ionic liquids (PILs) could be suggested as new, promising class of sorbents for absorption cooling purposes. This work is a continuation of our systematic investigation of an aqueous solution of lithium bromide in novel protic ionic liquids as a potential working fluid in absorption refrigeration technology. The thermodynamic and transport properties of lithium bromide in the aqueous solutions of three ethanolamine based protic ionic liquids based on 2-hydroxyethylammonium, bis(2-hydroxyethyl)ammonium, and tris(2-hydroxyethyl)ammonium with anion propionate were investigated through density, speed of sound, and viscosity measurements as a function of temperature and composition, and then some thermophysical parameters were obtained. The key parameters, such as apparent molar volume, apparent molar isentropic compressibility, and viscosity B-coefficients were calculated from the experimental data. The influence of temperature, concentration, and cation on the thermophysical properties was studied. The cospherical overlap model indicates the positive transfer values observed in the experimental data. The findings showed that interactions between lithium bromide and the PILs predominated in the systems under study and that these interactions increased as the PIL concentrations increased. The results were discussed in terms of various solute–solvent interactions present in the studied systems.