Abstract
The solubilities of DL-amino acid mixtures, glycine, alanine, and serine dissolved in water measured at 298.15 K are presented. An extended form of the UNIFAC model taking into account the dipole-dipole interaction between the amino acids in aqueous mixture was developed to predict the experimental results. The dipole moment of amino acids was estimated by the method of the quantum mechanical approach using a Hyperchem molecular modeling software. The magnitude of dipole-dipole interaction term in the activity coefficient of dipolar amino acids was examined using the present model. The binary UNIFAC interaction parameters of anionic and cationic groups in the amino acids were evaluated from the experimental binary activity coefficient data. The present model can accurately represent the experimental solubilities of the two amino acids in water using only pure and binary information constituting the ternary mixture.
