Generation of iron(VII) oxide in aqueous solution, a new oxidant in water treatment

Current oxidation methods for water treatment are limited due to the presence of recalcitrant contaminants such as pharmaceuticals and per- and polyfluoroalkyl substances, requiring new stronger and safe oxidants. Here we synthesized a novel iron oxide in oxidation state + 7, Fe VII O 4 − , in water by one-electron oxidation of ferrate(VI) by an hydroxyl radical. The kinetics and spectral measurements were collected using a pulse radiolysis technique under mild alkaline condition. Fe VII O 4 − can be produced in microseconds with a visible spectrum maximizing at 680 nm. The formation of Fe VII O 4 − in water is supported by density-functional theory calculations. The calculated standard redox potential of ~ 1.7 V suggests its potential in treating water efficiently.