Densities, Viscosities, Electrical Conductances, and Refractive Indices of Amino Acid + Ionic Liquid ([BMIm]Br) + Water Mixtures at 298.15 K

Abstract

Densities, viscosities, electrical conductances, and refractive indices of the amino acids glycine, l-alanine, and l-valine in aqueous ionic liquid, 1-butyl-3-methylimidazolium bromide ([BMIm]Br), solutions have been measured at 298.15 K. These data have been used to calculate apparent molar volumes, Vϕ, viscosity B-coefficients and ion association constants, Ka, for the mixtures studied. The limiting partial molar volumes, Vϕ0, and transfer partial molar volumes, ΔtrVϕ0, have been determined. It has been observed that both Vϕ0 and ΔtrVϕ0 values for amino acids increase with increasing ionic liquid concentrations. The linear correlation of Vϕ0 and B-coefficient values with the number of carbon atoms in alkyl chain of the amino acids have been used to estimate the contribution of charged end groups (NH3+, COO−). All these parameters was used to interpretate solute−solvent interactions occurring between the various components in these ternary mixtures. Limiting molar conductivities, Λ0 and ion association constants, Ka of ionic liquid were obtained from the low concentration chemical model (lcCM) of the conductance equation.