Formal oxidation potentials of actinide couples in K10P2W17O61 solutions

Abstract

The formal oxidation potentials of the M(VI)/M(V), M(V)/M(IV), and M(IV)/M(III) couples for actinides from U to No and of the M(IV)/M(III) couples for some actinides in 1 M H+ or 1 M Na+ (pH ∼5–5.5) solutions containing K10P2W17O61 were calculated from the data on stability of complexes of f element ions with the unsaturated heteropolytungstate anion P2W17O 61 10− . In some cases, the previously accepted values were subjected to major revision, especially the potentials of the An(V)/An(IV) couples. Problems arising in measuring the potentials of the couples involving Np(III) and Pu(III) which react with the heteropolyanion to form a heteropoly blue are discussed. The potentials of some M(III)/M(II) couples are estimated.