Effect of ionic liquids, 1-butyl-3-methyl imidazolium bromide and 1-hexyl-3-methyl imidazolium bromide on the vapour - Liquid equilibria of the aqueous D-fructose solutions at 298.15 K and atmospheric pressure using isopiestic method

In this study, water activity measurements have been carried out by the isopiestic method for the systems (D-fructose + 1-butyl-3-methyl imidazolium bromide + H2O) and (D-fructose + 1-hexyl-3-methyl imidazolium bromide + H2O) at 298.15 K and atmospheric pressure. Vapour pressures and osmotic coefficients of the solutions have been determined from the experimental measured water activity results. The experimental water activity values were satisfactorily correlated with segment-based local composition models of the Wilson, NRTL, modified NRTL, NRF-NRTL and UNIQUAC. Then, using the parameters obtained from these models, the unsymmetrical molal activity coefficients of the D-fructose and ionic liquids in the binary and D-fructose in ternary aqueous solutions have been calculated. Furthermore, the activity coefficients of D-fructose in binary and ternary solutions were used to calculate the Gibbs energy of transfer for D-fructose from water to aqueous ionic liquid solutions. An application of McMillan-Mayer theory of solutions through virial expansion of transfer Gibbs energy was made to get pair and triplet interaction parameters and salting constant values. From the sign and magnitude of these parameters and salting constants and also from the magnitude of activity coefficients some information about solute-solute and solute-solvent interactions are obtained. (C) 2016 Elsevier Ltd.