Thermodynamic properties of D-glucose in aqueous 1-hexyl-3-methylimidazolium bromide solutions at 298.15 K

Various thermodynamic and thermophysical properties, such as density, molar conductivity, and refractive index for {D-glucose + ionic liquid, 1-hexyl-3-methylimidazolium bromide ([HMIm]Br), + H2O} solutions have been measured at 298.15 K. The calculated volumetric properties containing standard partial molar volumes (V-phi(0)) and corresponding transfer volumes (Delta V-tr(phi)0) were used to interpret solute-solvent interactions. An increase was observed in the V-phi(0) and Delta V-tr(phi)0 values with increasing the ionic liquid concentration. This observation indicates that there are interactions between [HMIm]Br and the hydrophilic-OH and-O-groups of D-glucose, providing that the ionic liquid has a dehydration effect on the D-glucose solutions. To confirm this result, limiting molar conductivities (Lambda(0)) and ion association constants (K-a) for [HMIm]Br in aqueous D-glucose solutions have been estimated by low concentration Chemical Model (IcCM). These quantities decrease with increasing the concentration of D-glucose, suggesting strong interactions between the ionic liquid and D-glucose. The values of molar refractions (R-D) obtained from refractive index measurements show an increase upon increasing both D-glucose and the ionic liquid concentrations. It was also attempted to make a comparison between the results obtained here and those of our previous works to investigate the effect of the cation size of ionic liquid on the solute-solvent interactions. (c) 2012 Elsevier B.V. All rights reserved.