Volumetric, viscometric and spectroscopic studies of molecular interactions of glutamic acid with potassium sorbate and sodium benzoate in aqueous medium at T = 293.15–313.15 K

Abstract

The empirically procured data of physical properties like density and viscosity for the solutions of glutamic acid (Glu) with various concentrations in H2O and H2O + (1.5, 2.0 and 2.5 mol.kg-1) potassium sorbate (PS)/sodium benzoate (SB) at five different temperature (T = 293.15–313.15 K) and atmospheric pressure (101.1 kPa) has been used in order to calculate volumetric and viscometric parameters such as apparent molar volume (Vϕ), partial apparent molar volume (V∅0), limiting apparent molar expansibility (E∅0), viscosity B-coefficients (BJ), pair and triplet interaction co-efficients etc. Structure making properties of glu being present with PS/SB in the solutions are explained by the positive Hepler’s constant (∂2V∅0/∂T2)P values. This structure building tendency of Glu is further supported by the positive (BJ) and negative (∂BJ/∂T) values. For both solute and solvent Gibbs free energy of activation (Δμ10,#andΔμ20,# respectively) has been evaluated and including these parameters the thermodynamic parameters like ΔS0,#andΔH0,# profound the stability of the transition state. For a refined understanding of distinct intermolecular interactions prevailing in the designed systems the co-sphere overlap model has been employed. The procured results acknowledge that solute-solvent interactions reduce with a rise in temperature. Additionally, FTIR spectral analysis was carried out on the studied systems and relying on the shifting oh O-H stretching band the presence of hydrogen bond as well as different kinds of interactions are confirmed for the investigated system.