Effect of tetrabutylammonium hydrogen sulphate on the Solution thermodynamics of thiamine hydrochloride in aqueous solutions

The densities and viscosities of thiamine hydrochloride (vitamin-B-1) in aqueous tetrabutylammonium hydrogen sulphate (Bu4NHSO4) solutions with several molal concentrations (m(Bu4NHSO4) = 0.000, 0.005, 0.010, 0.015 and 0.020mol center dot kg(-1)) of Bu4NHSO4 were determined at T = (298.15, 308.15 and 318.15) K under atmospheric pressure. Using experimental data apparent molar volume (phi v), standard partial molar volume ((0)(phi v)), the slope (S-v), standard isobaric partial molar expansibility (phi(0)(E)) and its temperature dependence (partial derivative phi(0)(E)/partial derivative T)(P), the viscosity B-coefficient and solvation number (S-n), etc., were determined. Viscosity B-coefficients were further utilized to obtain the free energies of activation of viscous flow per mole of the solvents (Delta mu(0 not equal)(1)) and of"the solute (Delta mu(0 not equal)(2)). Effects of molality, solute structure and temperature on all these parameters were analyzed in term of ion-ion and ion-solvent interactions; results revealed that the solutions are characterized predominantly by ion-solvent interactions and thiamine hydrochloride behaves as a long-range structure maker. (C) 2016 Elsevier B.V. All rights reserved.