Patent ID: 8449756

Claim:
A method for making ferrate(V) and/or ferrate(VI) comprising: providing an electrochemical cell comprising an iron-containing anode, a cathode, and an electrolyte solution, wherein the electrolyte solution comprises an alkaline solution of at least one hydroxide; and applying a continuously and automatically varied variable direct current voltage between the anode and the cathode to form the ferrate(V) and/or ferrate(VI), the variable direct current voltage varying between a maximum voltage (Vmax) and a minimum voltage, the minimum voltage (Vmin) is greater than 0 and is a voltage to ensure that formation of an oxide film on a surface of the anode is depressed so that passivation of the anode is substantially avoided, wherein Vmin is high enough to maintain oxidizing conditions favorable for making the ferrate(V) and/or ferrate(VI) at the anode surface.