ELECTROCHEMICAL PROPERTIES AND THERMODYNAMIC STABILITY OF PU AND NEIGHBORING ACTINIDES IN THE (IV) AND (V) OXIDATION-STATES IN AQUEOUS ALKALINE MEDIA AND RADWASTES
Vf. Peretrukhin et al., ELECTROCHEMICAL PROPERTIES AND THERMODYNAMIC STABILITY OF PU AND NEIGHBORING ACTINIDES IN THE (IV) AND (V) OXIDATION-STATES IN AQUEOUS ALKALINE MEDIA AND RADWASTES, Radiochimica Acta, 65(3), 1994, pp. 161-166
In alkaline media Pu(V) is reduced to Pu(IV) and Pu(III) at a mercury
electrode at -0.72 and -1.1V/S.H.E. respectively, while Am(V) is reduc
ed to hydrolysed Am(IV) at a Pt cathode at +0.2V. The apparent redox p
otential Am(V)/Am(IV) is consistent with earlier published data, while
that of Pu(V)/ Pu(IV) = -0.72 V differs significantly from the publis
hed data between +0.4 and +0.9 V. Our data are consistent with the rep
orted high stability of Pu(V) in alkaline media. It is concluded that
Pu(V) cannot disproportionate in these conditions. Electrochemical red
uction of U(V) and Np(V) is not observed in 1 to 10M NaOH solutions at
significantly negative potentials. Hence the estimations of (V)/(IV)
potentials for U and Np in 1 M NaOH should also be corrected. A simila
r study has been undertaken at a pH closer to neutrality and the stabi
lity of pentavalent actinides at this pH is also discussed.