Solvation of Basic and Neutral Amino Acids in Aqueous Electrolytic Solutions: Measurements and Modeling

Abstract

The molal solubilities, density, and refractive index of the basic amino acid (l-lysine) and the neutral amino acid (l-cysteine) in aqueous solutions of potassium iodide (KI), sodium bromide (NaBr), sodium chloride (NaCl), sodium sulfate (Na2SO4), and calcium chloride (CaCl2) at 298.15 K were determined experimentally. From the values of the measured refractive indices, molal solubilities, and the densities, the excess refractive indices, the molar refractions, the polarizabilities, and the apparent molar volumes of the systems under study were calculated and discussed. The solvation of the amino acids under study was discussed in terms of their molal solubilities, apparent molar volume, and refractive index data. The phase diagrams of the studied tricomponent systems (water–salt–amino acid) were also determined and discussed. The solubility of l-cysteine and l-lysine were discussed in terms of the nature of the electrolytic salts under study. The effect of the electrolytic solutions under study on the so...