Solute–solute and solute–solvent interactions of l-histidine and l-arginine in aqueous-streptomycin sulphate solutions at different temperatures: A physicochemical study

Abstract

The densities, ρ of l-histidine and l-arginine in water and in aqueous-streptomycin sulphate [1% (0.0069mol·kg−1) and 2% (0.0137mol·kg−1) streptomycin sulphate in water] mixed solvents were measured at temperatures 293.15, 298.15, 303.15, 308.15, 313.15 and 318.15K; and ultrasonic speed, u and viscosities, η of these solutions were measured at temperatures 298.15, 303.15, 308.15, 313.15 and 318.15K and at atmospheric pressure. The ρ, u and η data have been used to calculate apparent molar volume, Vφ, limiting apparent molar volume, Vϕ°, apparent molar compressibility, Ks,ϕ, limiting apparent molar compressibility, Ks,ϕ°, transfer volume, Vϕ,tr°, transfer compressibility, Ks,ϕ,tr°, and partial molar expansibility, Eϕ°. The viscosity data have been used to determine Falkenhagen coefficient, A, Jones–Dole coefficient, B, free energy of activation of viscous flow per mole of solvent, Δμ1°# and per mole of solute, Δμ2°#. The calculated parameters have been discussed in terms of various solute–solute and solute–solvent interactions prevailing in these solutions. The structure making/breaking ability of the amino acids in the aqueous-streptomycin sulphate solution is also discussed.