Chronopotentiometric studies on dialytic properties of glycine across ion-exchange membranes

Chronopotentiometric responses of cation exchange membranes (CEMs) and anion exchange membranes (AEMs) were investigated in dilute solutions of NaCl, HCl and NaOH and its 1: 10, 10: 1 or 10: 10 mixture with glycine. The behavior of both of these membranes was nearly ideal in strong electrolyte solutions. From experimental data, the values of permselectivity, counter-ion transport number and membrane resistance corresponding to each type of membrane at different concentrations of strong electrolyte have been studied. Glycine solution alone at iso-electric pH (5.90) did not exhibit any good inflection for ion-exchange membrane due to the absence of ionic transportation. The presence of glycine along with NaCl (pH = 5.80) reduces ionic migration due to masking of ionic sites on the membrane matrix. The extent of masking was found to be proportional to the glycine concentration in the bulk of solution. Furthermore, the electro-transport of gly(+) and gly(-) is possible across the CEM and AEM, respectively. Data are useful in order to ensure efficient desalting of amino acids or for its electro-driven separation. (C) 2002 Elsevier Science B.V. All rights reserved.