Insights into the oxidative capacity of ferrate(IV,V)

This article summarizes the preparation methods and properties of FeO 4 3− (V), FeO 4 4− (IV), and FeO 3 2− (IV). The oxidative capacities of FeO 4 3− (V) and FeO 3 2− (IV) in water treatment applications are discussed, and the factors influencing these reactivities are explored. Thorough analysis reveals that ferrate(VI) generates intermediate species FeO 4 3− (V) and FeO 3 2− (IV) during self-decay and activation processes. Notably, the formation of FeO 4 3− (V) significantly enhances the efficiency of organic pollutant degradation; under both acidic and alkaline conditions, the oxidative capacity of FeO 4 3− (V) exceeds that of FeO 4 2− (VI). Under alkaline conditions, the oxidative capacity of FeO 4 3− (V) even surpasses that of SO 4 •- and • OH. The oxidative capacity of FeO 3 2− (IV) is not as strong as previously reported; under alkaline conditions, it has a higher oxidative capacity than FeO 4 2− (VI), whereas under acidic conditions, it has a lower oxidative capacity than FeO 4 2− (VI).