Temperature-dependent physicochemical interactions and spectroscopic characterization of sodium nitrate/sodium citrate in aqueous sodium salicylate solutions

Abstract

This study investigates the thermodynamic properties of ternary solutions comprising sodium nitrate/sodium citrate in sodium salicylate solutions at 0.010, 0.020 and 0.030 mol·kg^-1 concentrations. Measurements of density and speed of sound were carried out across four temperatures (288.15 to 318.15) K with a gap of 10K at 0.1 MPa. pressure. Key factors like apparent volume per mole $V_{\varphi }$, partial volume per mole $V_{\varphi }^0$, and the change in partial molar volume of transfer $\Delta V_{\varphi }^0$, were derived from experimental density measurements, while apparent isentropic compression per mole $K_{\varphi ,s}$ and partial isentropic compression per mole $K_{\varphi ,s}^0$; were computed using speed of sound measurements. Pair and triplet coefficients were analyzed to unveil solute and solvent and solute-solute interactions. In addition, Relative association (R_a) and relaxation strength ($r_s$) were calculated, showing a decrease in solute-solvent interactions with adding of salts and rising temperature. Further, an FTIR spectroscopic study of the mixtures (sodium salicylate + water) as well as (sodium Nitrate/sodium Citrate+ water) was conducted to provide further insight into the interactions of solutes and solvents. Spectroscopic results offer insights into solutions with implications for chemical engineering and materials science.