Explorations on Solute–Solvent Interactions of Tripotassium Citrate and Sodium Benzoate in Aqueous 1‑Ethyl-3-methylimidazolium Ethyl Sulfate Solutions: Physicochemical, Spectroscopic, and Computational Approaches

The present research work is concerned with the thermophysical properties of tripotassium citrate and sodium benzoate in aqueous (0.10, 0.15, and 0.20) mol·kg–1 1-ethyl-3-methylimidazolium ethyl sulfate solutions at temperatures ranging (293.15–313.15) K and 101.3 kPa pressure. The experimentally acquired density, sound speed, and viscosity data have been employed to determine numerous densimetric, acoustic, and viscometric parameters including the apparent molar volumes (Vϕ), partial molar volumes at infinite dilution (Vϕ0), limiting apparent molar expansibilities (Eϕ0), apparent molar isentropic compressibilities (Kϕ,s), transfer properties, hydration number (nH), viscosity B-coefficients, and thermodynamic parameters of viscous flow (Δμ10, Δμ20, ΔH20, and TΔS20). The above-mentioned parameters have been evaluated for the examination of interactions that are prevailing among tripotassium citrate/sodium benzoate and 1-ethyl-3-methylimidazolium ethyl sulfate in an aqueous medium. In addition, UV spectral analysis was used for the examination of interactions existing among the considered systems. Furthermore, the band gaps between the highest occupied molecular orbital and the lowest unoccupied molecular orbital for the studied systems and the interaction characteristics have been calculated using density functional theory. The obtained results inferred the predominance of the hydrophilic–hydrophilic interactions in the systems under investigation