Study of Molecular Interactions between Potassium Chloride and Ionic Liquid 1-Methyl-3-propylimidazolium Iodide in Aqueous Solutions at Different Temperatures: A Thermodynamic Approach

In the present communication, we report the experimental measurements of density and speed of sound for potassium chloride (KCl) in aqueous 0.05 and 0.10 mol·kg^–1 1-methyl-3-propylimidazolium iodide ([MPIm][I]) ionic liquid solutions at 288.15–318.15 K. Further, the experimental density and speed of sound data were utilized to calculate apparent molar volume of solute, apparent molar volume of solute at infinite dilution, apparent molar expansivity of solute at infinite dilution, isentropic compressibility of solution, apparent molar isentropic compressibility of solute, and apparent molar isentropic compressibility of solute at infinite dilution at studied temperatures. From Hepler’s constant outcomes, the structure-making or structure-breaking behavior of the solute has been evaluated in the studied aqueous ternary solutions. The results shed light on the potential of ionic liquids in optimizing industrial processes, such as tribology, extraction methods, and energy-related applications, by revealing significant solute–solute and solute–solvent interactions. This work contributes to a deeper understanding of the influence of ionic liquids on electrolyte behavior in aqueous media, highlighting its broader industrial and scientific relevance.