Solute–solvent interactions of glycine, L–alanine, and L–valine in aqueous 1–butyl–3–methylimidazolium methylsulfate ionic liquid solutions at different temperatures

The intermolecular interactions of amino acids (glycine, L–alanine, and L–valine) in aqueous solutions of an ionic liquid, 1–butyl–3–methylimidazolium methylsulfate [Bmim][MeSO₄] as a function of temperature have been investigated by combination of volumetric and acoustic methods. The density, $\rho$, and speed of sound, $u$, of glycine, L–alanine and L–valine in aqueous 1–buytl–3–methylimidazolium methylsulfate solutions have been measured in the temperature interval T = (288.15, 298.15, and 308.15) K and atmospheric pressure. These data have been used to calculate apparent molar volume $\left(V_{\varnothing }\right)$, and apparent molar adiabatic compressibility $\left(K_{\varnothing ,s}\right)$ of these mixtures at different temperatures. Later, the standard partial molar volume $\left(V_{\varnothing }^0\right)$, standard partial molar volumes of transfer $\left(\Delta V_{\varnothing }^0\right)$, standard partial molar adiabatic compressibility $\left(K_{\varnothing ,s}^0\right)$, and standard partial molar adiabatic compressibility $\left(\Delta K_{\varnothing ,s}^0\right)$ of transfer have been determined for these amino acid solutions from density and speed of sound data. Also, hydration number $\left(n_H\right)$ and various group contribution have been calculated. Finally the results have been interpreted in terms of solute - solvent interactions that exist among the currently investigated systems.