Thermodynamic studies on the phase equilibria of ternary {ionic liquid, 1-hexyl-3-methyl imidazolium chloride + D-fructose or sucrose + water} systems at 298.15 K

• VLE data for aqueous saccharide + [HMIm]Cl systems were measured.
• Performances of local composition models were tested in fitting VLE data.
• Molal activity coefficients were calculated.
• Gibbs energy of transfer for saccharides in ternary solution were calculated.

In this work, to study vapor-liquid equilibria of ternary {ionic liquid, 1-hexyl-3-methyl imidazolium chloride + D-fructose or sucrose + water} systems, water activity measurements have been made using an improved isopiestic method at 298.15 K. Segment-based local composition models of the Wilson, NRTL, modified NRTL, NRF-NRTL and UNIQUAC were accurately used to correlate the measured water activity data and parameters obtained from these models were utilized to calculate the unsymmetrical molal activity coefficients of the ionic liquid in the binary and saccharides in binary and ternary aqueous solutions. Furthermore, the Gibbs energy of transfer for D-fructose and sucrose from water to aqueous ionic liquid solutions has been determined from the activity coefficients of D-fructose and sucrose in binary and ternary solutions. Using McMillan-Mayer theory of solutions, pair and triplet interaction parameters and salting constant values were computed. Finally, from the magnitude of activity coefficients and the sign and magnitude of salting constant some information about solute-solute and solute-solvent interactions are obtained in these (saccharide + ionic liquid + water) systems.