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

摘要

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 (V_φ), standard partial molar volumes (V_φ~0), transfer partial molar volumes (Δ_(tr)V_φ~0) and hydration number (n_H). The trend of ΔtrV0φ 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.