The cyclic voltammetric study of ferrate(VI) formation in a molten Na/K hydroxide mixture

The electrochemical synthesis of ferrate(VI) was studied in a molten salt environment as a function of temperature (170–200 °C). A eutectic NaOH–KOH melt was selected as the most appropriate system for this purpose. Cyclic voltammetry was used to characterize the processes taking place on the stationary iron electrode. The anodic current peaks corresponding to the ferrate(VI) production as well as cathodic current peaks corresponding to the ferrate(VI) reduction appeared to be strongly dependent on the temperature at which the experiment was performed. Ferrate(VI) formation by anodic oxidation of the iron electrode in the molten electrolyte during the batch electrolysis was confirmed for the first time by visible and Mössbauer spectroscopy. The maximum current efficiency of Fe(VI) formation reached during galvanostatic batch electrolysis has attained 72%. It was reached at the temperature of 170 °C.