Zusammenfassung
In the present work, osmotic coefficients of aqueous mixtures of guanidinium chloride (GndmCl) and sodium l-aspartate (Na-l-Asp = (S)-aminobutanedioic acid sodium salt), previously determined at T = 298.15 K and 310.15 K, were described by ePC-SAFT (equation of state) and molecular interactions in ternary systems were deduced from activity coefficients. The electrolyte Perturbed-Chain Statistical ...
Zusammenfassung
In the present work, osmotic coefficients of aqueous mixtures of guanidinium chloride (GndmCl) and sodium l-aspartate (Na-l-Asp = (S)-aminobutanedioic acid sodium salt), previously determined at T = 298.15 K and 310.15 K, were described by ePC-SAFT (equation of state) and molecular interactions in ternary systems were deduced from activity coefficients. The electrolyte Perturbed-Chain Statistical Associating Fluid Theory ePC-SAFT, based on Wertheim's TPT1 perturbation theory is proved to be an excellent tool to model ternary amino acid salt + salt + water systems. ePC-SAFT modeling required the following steps. First, all the pure-component parameters were inherited from literature. Second, the binary interaction parameters to water were used as determined from the literature as well. Finally, a binary interaction parameter was required between the salt ion and the amino acid salt. We found that a satisfying modeling was obtained by setting the binary parameters between anion and cation to zero and using a binary interaction parameter k(ij) = -0.1 for Gndm(+) and the amino acid salt. Without fitting any additional parameters, osmotic coefficients, activity coefficients of water and of the solutes have been calculated, in good agreement with the experimental data.
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