Electrosynthesis of ferrate in a batch reactor at neutral conditions for drinking water applications

We report on the electrochemical generation of ferrate species in a batch reactor at neutral conditions (pH ∼7) using boron‐doped diamond (BDD) electrodes and Fe (III) salts for applications in drinking water treatment. The impact of several relevant variables, including current density (5–55 mA cm−2), pH (5–8), and type and concentration of the dissolved iron salts on the production of ferrates were examined. In addition, linear sweep voltammetry (LSV) studies were conducted using buffered electrolytes with and without the presence of iron (III) to decouple the parasitic oxygen evolution reaction. The LSV measurements in the presence of iron (III) and with a neutral electrolyte exhibit oxidation peaks centered ∼2.0 V (versus SHE), indicating the production of ferrates at this pH. The rate of ferrate generation is not strongly affected by the pH condition (≤ 20 %); however, current density and the source of iron were found to have a higher impact on the production rate of ferrates. The efficacy of the process was higher using FeCl3 instead of other sources of iron such as Fe2O3 and FeO(OH). The batch reactor results were successfully interpreted by a simple model that considered the kinetics of the ferrate generation and degradation reactions.