Electrochemical Behavior of Cerium (IV) Species in n-TriButylPhosphate

This work investigates the electrochemical behavior of Ce(IV) complexes extracted in n-tributylphosphate (TBP) from nitric aqueous solutions as an entry to the direct electrochemical characterization of plutonium in organic extractants related to nuclear fuel reprocessing. Ce(IV) complexes displayed a reversible electrochemical reduction wave in TBP, which could be observed only at glassy carbon electrodes. At slow scan rates, that reduction wave showed a Nernstian dependence on the logarithm of both nitric acid and TBP concentrations in the organic phase, featuring the exchange of nitrates and TBP upon reduction to Ce(III). The presence of increasing amounts of a common degradation product of TBP, such as hydrodibutyl phosphate (HDBP) resulted in a shift of the Ce(IV) reduction wave towards more negative potential values, a behavior consistent with the formation of HDBP-Ce (IV) complexes.