Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

Mutual diffusion coefficients for aqueous solutions of 3-aminopropanoic acid (ss-alanine), 4-aminobutanoic acid (?-aminobutyric acid), 5-aminopentanoic acid, 6-aminohexanoic acid, and 7-aminoheptanoic acid at infinitesimal concentration were measured at atmospheric pressure and temperatures from (298.2 to 333.2) K using the Taylor dispersion method. The results were compared with those of the structural isomers measured in our previous studies to examine the effect of position of amino and carboxylic acid groups on the values of diffusion coefficients. The diffusion coefficients of all amino acid isomers were almost the same, indicating that the diffusion coefficients of amino acids measured in our studies were mostly determined by the molar mass and the increase in the distance between amino and carboxylic acid groups was not an important factor. The temperature dependences of the diffusion coefficients were well-correlated with viscosity of water, ?, as D12/T = a?ss where D12 is the diffusion coefficient at infinitesimal concentration of solute, T is the absolute temperature, and a and ss are the fitting parameters.