Evaluating thermodynamic characteristics of ternary (NaCl+ monosodium L-aspartate +H₂O) system by potentiometry and vapour pressure osmometry at different temperatures: modelling by Pitzer ion-interaction model

Thermodynamic investigation of ternary (NaCl+NaAsp+H₂O) electrolyte system was conducted based on potentiometric and vapour pressure osmometry methods at <i>T</i> = (298.2 ± 1.1 and 310.2 ± 1.1) K and ambient pressure. The potentiometric measurements for this system were performed on the galvanic cell of the type of Ag| AgCl| NaCl (m₁), NaAsp (m₂) | Na-ISE over total ionic strengths of 0.001–3.000 mol. kg⁻¹. The vapour-liquid equilibrium data for the aqueous solution of NaAsp were determined through the VPO method at <i>T</i> = 298.2 ± 1.1 K. Pitzer ion-interaction model was applied for the modelling of the NaCl+NaAsp+H₂O. Unknown Pitzer mixing interaction parameters (θClAsp &amp; ψAspNaCl) were calculated. For the NaCl+NaAsp+H₂O, at <i>T</i> = 298.2 ± 1.1 K, a θClAsp of −0.240 and ψAspNaCl of 504.0, was estimated. At <i>T</i> = 310.2 ± 1.1 K, θClAsp &amp; ψAspNaCl were calculated as −0.377 and 475.0, in order. The mean activity coefficients of NaAsp, osmotic coefficients and the excess Gibbs free energies for the studied mixed electrolyte system were calculated by the provided data from the Pitzer model.