Volumetric and conductometric studies of some amino acids in aqueous ionic liquid, 1-hexyl-3-methylimidazolium chloride solutions at 298.15 K

Abstract

Densities and molar conductivities of some amino acids (glycine, L-alanine and L-valine) in aqueous ionic liquid, 1-hexyl-3-methylimidazolium chloride, [HMIm]Cl solutions have been measured at 298.15 K. The measured densities have been used to calculate apparent molar volumes (), standard partial molar volumes (), transfer partial molar volumes () and hydration number (n H). The trend of has been interpreted in terms of solute–solvent interactions on the basis of a cosphere model. Also, a decrease in hydration number of the glycine with increasing [HMIm]Cl concentrations due to stronger dehydration effect of [HMIm]Cl with the charged centre of the zwitterions of the glycine has been explained. Additionally, the limiting molar conductivity (Λ 0) and ion association constants (K a), for the mixtures studied, decrease with the molality of amino acid which are attributed to the interaction of [HMIm]Cl with the amino acids and increasing viscosity of the mixture.