Determination of the stability constants of uranyl/polymer complexes by differential pulse polarography

Differential pulse polarography (DPP) allows for the determination of the stability constants (K) and the stoichiometry (n) for the complexation of the UO22+ ion by various monomers and the parent polymers. The experimental observation is the shift of the totally reversible reduction wave UO22++e−⇌UO2+ toward more cathodic potentials when the complexing monomer or polymer is added to an uranyl nitrate aqueous solution. This shift is, however, much greater when the polymer is used rather than the monomer, in line with a higher stability of the complexes (Kpolymer≫Kmonomer). A theoretical stability scale of the polymers/UO22+ complexes was compared to an experimental one based on dynamic leaching tests.