Measurement and Modeling Solubility of Aqueous Multisolute Amino-Acid Solutions

The solubilities of the ternary mixtures l -alanine/ l -leucine, l -alanine/ l -valine, and l -leucine/ l -valine in water were measured at 303 and 323 K. The solubilities of seven binary, eight ternary, and one quaternary amino-acid systems were modeled using the PC-SAFT equation of state. For this purpose, new parameters for l -aspartic acid, l -glutamic acid, l -leucine, and l -tyrosine are presented. The model excellently reproduces binary solubility data with a linear temperature-dependent binary interaction parameter for the solute−solvent interaction. PC-SAFT allows for a very good prediction of the solubility behavior of ternary mixtures over a wide range of temperature and concentration. The aqueous mixture with three amino acids is then predicted without any further adjustment with an average relative deviation of 3.34%.