Ductile Iron: A Low-Cost Optimal Anode Material for Electrochemical Generation of Ferrate(VI)

Abstract

The effects of anode composition and temperature on anode electrochemical properties, the passivation layer’s structure, and ferrate (VI) generation in 14 M NaOH were investigated. Cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic polarization were used to analyze the electrochemical processes involving the electrosynthesis of ferrate using some low-cost anode materials: ductile iron, grey cast iron, and mild steel. The results proved that the presence of silicon and graphite with sphere form in the ductile iron anode significantly increased ferrate electro-generation. The optimal temperature for the electro-generation of ferrate was 30-40°C. The current efficiency using the ductile iron anode was constantly at least about 30% superior to that of the grey cast iron and mild steel electrodes. The ductile iron anode material was the most feasible option because it provides the highest ferrate concentration (1.58 g/L) with the highest current efficiency of 74% and the lowest specific energy consumption of 1.2 kWh/kg ferrate.