Volumetric and ultrasonic properties of α-amino acids (glycine, l-alanine and l-valine) in aqueous diammonium hydrogen phosphate at different temperatures and concentrations

Abstract

The density and speed of sound measurements have been carried out for some α-amino acids i.e. glycine, l-alanine and l-valine in aqueous diammonium hydrogen phosphate (DAP) at 10K intervals, from 288.15K to 318.15K and experimental pressure p=0.1MPa. We have utilized the density and speed of sound data for determining the apparent molar and partial molar parameters concerning volumetric and compressibility properties. The group contribution of amino acids to partial molar volumes has also been perceived. The pair and triplet interaction coefficients obtained from partial molar volumes of transfer and partial molar isentropic compression of transfer illustrate the dominance of pairwise interactions. The possible molecular associations such as solute-solvent and solute-solute etc. are revealed by the present work and in due course, it has also been observed that all the amino acids in our present study, act as structure makers in aqueous solution of diammonium hydrogen phosphate (DAP). Apparent molar properties and partial molar properties anticipate the dominance of strong solute–solvent interactions over weak solute-solute in the studied ternary system.