Conductance behavior of ionic liquids, 1-alkyl-3-methylimidazolium bromide, in aqueous d-xylose solutions

The electrical conductivity of a number of ionic liquids, 1-propyl-3-methylimidazolium bromide ([PrMIm]Br), 1-hexyl-3-methylimidazolium bromide ([HMIm]Br), 1-octyl-3-methylimidazolium bromide ([OMIm]Br) and 1-decyl-3-methylimidazolium bromide ([DMIm]Br), in the aqueous d-xylose solutions at several concentrations, (0.2, 0.5 and 0.8) mol kg−1 have been measured at 298.15 K. The obtained data have been analyzed using low concentration Chemical Model (lcCM) of conductance equation in terms of ion association constant (Ka), limiting molar conductivity (Λ0), Walden product (Λ0η) and distance parameter (R). It was observed that the Ka values decrease with increase in both alkyl chain of ionic liquid and d-xylose concentration. Gibbs free energy of ion pair formation (ΔGa0) was estimated using the Ka values. It was found that the ΔGa0 values are negative and became more negative with shorter alkyl chain length of ionic liquids and low concentration of d-xylose.