Electrochemical Behavior of Ce(IV)/Ce(III) Couple in N, N-di(2-ethylhexyl)-n-butanamide (DEHBA), N, N-Di(2-ethylhexyl)-iso-butanamide (DEHiBA), and N, N-Di(2-ethylhexyl)-3, 3-dimethyl Butanamide (DEHDMBA)

In this work we report on the electrochemical behavior of Ce(IV)/Ce(III) redox couple in pure N, N-dialkyl amides (N, N-DA), namely N, N-di(2-ethylhexyl)-n-butanamide (DEHBA), N, N-di(2-ethylhexyl)-iso-butanamide (DEHiBA), and N, N-di(2-ethylhexyl)-3, 3-dimethyl butanamide (DEHDMBA) equilibrated with nitric aqueous solutions as an entry to the direct electrochemical characterization of plutonium in these extractants. Ce(IV)/Ce(III) redox process was used as a model. Its potential (E_1/2 ≅ to 1.02 V/SCE) is not affected by the temperature and the nature of the N, N-DA and this clearly indicates that the functionalities of these extractants produce the same relative effect on both +IV and +III oxidation states of the cerium cation. Linear variations of the current intensity of the reduction peak of Ce(IV) with the concentration of Ce(IV)/N, N-DAs/HNO₃(5 M) solutions were obtained from cyclic voltammograms recorded at 25 degrees C and 40 degrees C. Due to the poor definition of the voltammograms in DEHiBA and DEHDMBA, such characterization allows only the evaluation of the performances of the chemical extraction of Ce(IV) from aqueous nitric acid solution by the undiluted DEHBA. To our knowledge, the electrochemical behavior of Ce(IV)/Ce(III) in N, N-DAs was not previously studied and our findings will for sure open the door for further investigations in this field. (authors)