Mechanism of Water Oxidation by Ferrate(VI) at pH 7–9

Abstract

Abstract The kinetics of water oxidation by K 2 FeO 4 has been reinvestigated by UV/Vis spectrophotometry from pH 7–9 in 0.2 m phosphate buffer. The rate of reaction was found to be second‐order in both [FeO 4 2− ] and [H + ]. These results are consistent with a proposed mechanism in which the first step involves the initial equilibrium protonation of FeO 4 2− to give FeO 3 (OH) − , which then undergoes rate‐limiting O−O bond formation. Analysis of the O 2 isotopic composition for the reaction in H 2 18 O suggests that the predominant pathway for water oxidation by ferrate is intramolecular O−O coupling. DFT calculations have also been performed, which support the proposed mechanism.