Effect of temperature on viscometric properties of aliphatic amino acids glycine/l-alanine/l-valine in aqueous solutions of tetraethylammonium iodide

Viscosities, η, for solutions of glycine, l-alanine and l-valine in (0.03, 0.05, 0.1, 0.15 and 0.2) mol·kg− 1 aqueous tetraethylammonium iodide (TEAI) at temperature T = (288.15, 293.15, 298.15, 303.15 and 308.15) K have been measured as a function of molality of amino acids. The viscosity B-coefficients for the amino acids in aqueous TEAI solutions have been calculated at different temperatures employing the Jones-Dole equation. The trends of variation in viscosity values of amino acids with an increase in molal concentration of TEAI solutions and also with an increase in temperature have been ascribed to the solute-solvent interactions operative in the solutions. The contribution of the solute to the activation parameters (Δμ20⁎, ΔH0⁎ and ΔS0⁎) for viscous flow of the solution has been obtained to throw light on the mechanism of viscous flow. The contributions of the charged end group (NH3+, COO−) and (CH2) groups of the amino acids to B-coefficient and Δμ20⁎ have also been estimated using the linear correlations between B-coefficient or Δμ20⁎ and the number of carbon atoms in the alkyl chains of the amino acids. All these parameters have been discussed in terms of the solute-solvent interactions in the ground and transition states.