Thermophysical properties of amino acids L-serine and L-leucine in aqueous diammonium hydrogen phosphate solutions: Volumetric and acoustic studies

Abstract

Densities and speeds of sound measurements have been done for the amino acids (AAs) L-serine and L-leucine in aqueous diammonium hydrogen phosphate (DAP) solution at different temperatures with a specific interval of temperature. Thermophysical parameters including apparent molar volume (Vϕ), partial molar volume (Vϕ0), apparent molar isentropic compression (Kϕ,s), partial molar isentropic compression (Kϕ,s0) and transfer volumes like partial molar volumes of transfer (ΔVϕ0) and partial molar isentropic compression of transfer (ΔKϕ,so) were determined using the measured experimental data. The co-sphere overlap model was used to interpret the sort of interactions dominating in the system. The obtained transfer quantities are positive which indicates the dominance of ion-hydrophilic and hydrophilic–hydrophilic interactions existing among the amino acids and diammonium hydrogen phosphate salt solution in aqueous medium. Pair and triple interaction coefficients calculated for the system of amino acids and phosphate salt in aqueous medium. Overall results have been elaborated in terms of the solute-solvent or solute-solute interactions prevailing in the system.