Kinetic and Mass-Transfer Parameters for Ce(III) Electro-oxidation in Nitric Acid with∕without Anion Impurities

Abstract

In this study, Koutecky–Levich (K-L) and cyclic voltammetry (CV) techniques were used to measure the kinetic and diffusion parameters for Ce(III) electro-oxidation on glassy carbon in with∕without , , or impurities. It was found that the apparent diffusion coefficients of Ce(III) determined using the K-L and CV approaches were and , respectively, while the values varied by to and to , respectively, for the single-impurity cases. For the three-impurity case, the value ) from K-L estimation was approximately three times that from the CV approach. The standard rate constants for Ce(III) oxidation estimated from the K-L and CV approaches were 2.63 and , respectively, whereas the values were lowered by 35–91% and 38–80%, respectively, for the case and by 46–49 and 33–58%, respectively, for the case. The multi-impurity case had the lowest rate constant around limiting current for Ce(III) oxidation. The obtained kinetic and diffusion data are useful for the design of Ce(III) to Ce(IV) electro-regenerating systems and the evaluation of using spent Cr-etching solutions as candidate electrolytes in zinc–cerium redox flow batteries.