Stability of metal uncharged ligand complexes in ion exchangers. Part 1.—Quantitative characterization and thermodynamic basis

Abstract

The thermodynamics of the formation of metal uncharged ligand complexes in ion exchangers is analysed in terms of an extension of the Bjerrum complex formation function. A new method is presented for obtaining the stability of adsorbed complexes which is based upon the measurement of the ion exchange adsorption of the metal complex vis-à-vis the aqueous metal ion. Quantitative relations between excess adsorption affinity and stability enhancement are presented; it is shown that absolute values of stability constants, determined by either one of the two complementary methods, are dependent upon the assumption of a unit partition coefficient for the uncharged ligand between the bulk solution and the ion exchanger.