Isopiestic determination of water activity and vapour pressure for ternary (ionic liquid, 1-hexyl-4-methyl pyridinium bromide + d-fructose or sucrose + water) systems and corresponding binary ionic liquid solutions at 298.15 K

Abstract

In this study, water activity and vapour pressure for ternary (ionic liquid, 1-hexyl-4-methyl pyridinium bromide+d-fructose or sucrose+water) systems have been determined by the isopiestic method at 298.15K. The experimental results for the activity of water were accurately correlated with NRTL model. Using the parameters obtained from this model, the unsymmetrical molal activity coefficients of the ionic liquid in the binary solution and saccharides in binary and ternary aqueous solutions were computed. Furthermore, the activity coefficients of saccharides in the binary and ternary solutions were used to calculate the Gibbs energy of transfer for saccharides from water to aqueous ionic liquid solutions. Pair and triplet interaction parameters and salting constant values were determined using McMillan-Mayer theory of solutions. From the behaviour of the molal activity coefficients of saccharides in the binary and ternary solutions, Gibbs energy of transfer and salting constant some information in regard to solute–solute and solute-solvent interactions in these (saccharide+ionic liquid+water) systems are obtained.