Mutual diffusion coefficients at infinitesimal concentration and atmospheric pressure were measured for binary aqueous solutions of four α-amino acids (2-amino-3-phenylpropanoic acid (phenylalanine), 2-amino-3-(4-hydroxyphenyl)propanoic acid (p-tyrosine), 2-amino-3-(3-hydroxyphenyl)-propanoic acid (m-tyrosine), and 2-amino-3-(2-hydroxyphenyl)propanoic acid (o-tyrosine)) at temperatures from (298.3 to 313.2) K and five aminobutyric acid isomers (2-aminobutanoic acid (α-aminobutyric acid), 2-amino-2-methylpropanoic acid (α-aminoisobutyric acid), 3-aminobutanoic acid (β-aminobutyric acid), 3-amino-2-methylpropanoic acid (β-aminoisobutyric acid), and 4-aminobutanoic acid (γ-aminobutyric acid)) at temperatures from (293.2 to 333.2) K. The diffusion coefficients for each of the amino acids were well-represented by a simple correlation as a function of temperature and solvent viscosity with two adjustable parameters determined for each solute. The two parameters determined for each amino acid in our present and previous studies were closely related to the molar volume of the amino acids at its normal boiling point. We proposed predictive correlations for the diffusion coefficients of aqueous amino acid solutions at infinitesimal concentrations and tested the accuracy of the predictions with the reference data for aqueous amino acids at 298.2 K.

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