Volumetric and transport properties of ternary solutions of l-serine and l-valine in aqueous NaCl solutions in the temperature range (293.15–323.15) K

Abstract

In this paper we report new density and viscosity data of l-serine and l-valine in aqueous NaCl solutions as a function of amino acids molality at fixed salt concentration (0.1, 0.2, 0.5, 0.7 and 1.0 mol·kg−1) and temperature T = (293.15, 298.15, 303.15, 308.15, 313.15, 318.15 and 323.15) K at atmospheric pressure of p = 0.1 MPa. From density, some derived properties such as the apparent molar volume, Vϕ, limiting partial molar volume, Vϕ0, and expansibility, Eϕ0, standard molar volume of transfer, ΔVϕ0, and hydration number, nH, were calculated and discussed in terms of solute–solvent interactions and structural effects. The Jones–Dole equation and transition state treatment were used to obtain the viscosity B coefficient, free energy of activation of viscous flow per mole of solvent, Δμ10#, and per mole of solute, Δμ20#, entropies, ΔS20#, and enthalpies, ΔH20#, of activation of viscous flow for amino acids. All the activation parameters were discussed in terms of transition state theory. The co-sphere overlap model was used to interpret the results. The structure making/breaking ability of the amino acids in solutions was also discussed.