ABSTRACT
Aspartic acid (Asp) and potassium sorbate (PS) were taken for this research. Solutions of Asp in water and aqueous PS media with different compositions were studied at 298.15 K for acoustic investigation. Compressibility data like isentropic compressibility 1, apparent molar isentropic compressibility (2), and isothermal compressibility 3were analyzed and are found to establish strong solute-solvent interactions. Attractive forces between polar groups and ions from Asp and PS affect the electrostriction of water molecules in the solvation shells as suggested by the limiting values of compressibility parameters. Derived parameters like acoustic impedance (Z), internal pressure 4, and relative ion association 5 support the presence of ion-hydrophilic interactions between zwitterionic centers of amino acid and ions of dissociated PS and hydrophobic interactions between the hydrocarbon backbones of Asp and PS and hydrophobic solvation of these nonpolar parts of the molecules. Shrinkage of hard core solvation spheres due to electrostatic attractions between the ions of Asp and PS is reflected in the variation of free length and free volume with concentrations of solutions.
