Interactions of L-Aspartic Acid with Aqueous Solution of 1,2-Propanediol at Different Temperatures: A Volumetric, Compressibility and Viscometric Approach.

The volumetric, acoustic and viscometric methods are used for investigating the interactions of L-aspartic acid (Asp) in aqueous solution of 1,2-propanediol (PD) over a temperature of (298.15, 303.15 and 308.15) K at atmospheric pressure. Using the experimental results, the apparent molar volume, Vφ, limiting apparent molar volume, V0φ, the slope, Sv, and partial molar volume of transfer, V0φ,tr, have been calculated from density data. The apparent molar isentropic compressibility, K φ,s, limiting apparent molar isentropic compressibility, K0φ,s, its slope, Sk, and partial molar compressibility of transfer, K0φ,s, tr, have been calculated from speed of sound data. These values are also used for calculating the number of water molecules hydrated, nH, to the Asp. The viscosity data has also been used to determine relative viscosity ηr, viscosity B-coefficients, temperature derivative of B-coefficients, dB/dT and viscosity B-coefficients of transfer, Btr. The calculated parameters have been discussed in terms of various solute-solute and solute-solvent interactions prevailing in these solutions. Further, a detailed insight into the physicochemical interactions between Asp and aqueous PD, e.g., ion-hydrophilic and hydrophilic-hydrophilic interactions along with the structure-making tendency have been retrieved through the perusal of these calculated parameters.