Analysing the molecular interactions of ternary (lactose + water + tributylmethylammonium chloride) solutions at different temperatures via physicochemical methods

Abstract

The interactions of lactose with tributylmethylammonium chloride (Bu3MeNCl) as the function of temperature have been studied by amalgamation of volumetric, acoustic and viscometric methods. Density, ultrasonic speed, and viscosity for varying concentrations of lactose in water and in (0.020, 0.039, 0.059, 0.079) mol.kg−1 aqueous solutions of Bu3MeNCl have been determined at five distinct temperatures (T = 293.15–313.15) K. These experimental values have been used to calculate apparent molar volume, Vϕ, limiting apparent molar volume, V0ϕ, apparent molar isentropic compression, Kϕ,s, limiting apparent molar isentropic compression, K0ϕ,s, viscosity B-coefficient, their transfer values, pair and triplet interaction coefficients, and hydration number nH. The Gibbs free energy of activation for solvent (Δµ01#) and Gibbs free energy of activation for lactose (Δµ02#) in water and in aqueous solutions of Bu3MeNCl have also been assessed and the obtained results support the outcome of volumetric, acoustic and viscometric parameters. These parameters provide better understanding of molecular interactions like solute-solute, solute-solvent interactions present in the systems. Further, it helps in determining structural and functional properties of studied systems and acquired results revealed that the solutions are characterized predominantly by solute-solvent interactions. Also, the values of second derivative of limiting apparent molar volume with respect to temperature indicated that the lactose monohydrate behaves as a structure maker in aqueous tributylmethylammonium chloride solutions.