Hydration and sorption of amino acids by an iminophosphonic ion exchanger

Abstract

The interaction of glycine ions and a-alanine with an iminophosphonic Purolite S950 ion exchanger in the protonated form has been studied, and the equilibrium characteristics of ion-exchangeable and nonexchangeable sorption of amino acids have been determined. A quantitative evaluation of the degree of hydration, including the ratios of water with different energies in the phase of the exchanger in the protonated and amino acid forms, has been conducted; the changes in the Gibbs free energy and enthalpies of hydration and dehydration of PuroliteS950 have been determined. It has been found that polyampholyte in the protonated form manifests the greatest sorption capacity during sorption of bipolar amino acid ions. The amount of water of near hydration is the same for hydrogen and alanine forms of the ion exchanger; the greatest changes in the Gibbs energy are observed upon hydration of the alanine form, and those in the enthalpy are found for the hydrogen form of the polyampholyte.