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 ϕ 0 ) and corresponding transfer volumes ( Δ tr V ϕ 0 ) were used to interpret solute–solvent interactions. An increase was observed in the V ϕ 0 and Δ tr V ϕ 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 (Λ0) and ion association constants (Ka) for [HMIm]Br in aqueous d-glucose solutions have been estimated by low concentration Chemical Model (lcCM). 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 (RD) 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.