Electrochemical formation of ferrate(VI) in a molten NaOH–KOH system

Ferrate(VI) (FeO42-) has been produced electrochemically for the first time in a molten NaOH–KOH mixture at 200 °C. Cyclic voltammetry was used to characterize the synthesis process. Formation of FeO42- ion in a molten mixture system was observed both at an inert electrode in contact with Fe(III) ions and at iron electrode. An anodic wave corresponding to the FeO42- ion production occurred in the potential region where evolution of oxygen commences. The counter current peak during the cathodic potential scan indicates insignificant passivation of the iron electrode surface at FeO42- ion formation potential. Molten salt electrochemical ferrate(VI) synthesis method offers advantages over synthesis in aqueous solution such as no decomposition of FeO42- ion by water, lack of passive layer formation on the iron electrode, and increased anode process efficiency.