Enhanced electro-generated ferrate using Fe(0)-plated carbon sheet as an anode and its online utilization for removal of cyanide.

Efficient electrochemical generation of ferrate (Fe(VI)) is still challenged by the passivation of iron materials. Herein, we employed Fe(0)-plated carbon sheet as an anode to enable an efficient production of Fe(VI) with its concentration reached up to 55 mM, which was 8 times higher than that with iron sheet of the same size as an anode. The SEM results showed that the close and uniform dispersion of tapered Fe(0) particles on the surface of carbon sheet helped prevent the formation of passivated layer. The preparative process of electro-deposited Fe(0) affected the generation of Fe(VI). The increase of electroplating time to 40 min and electroplating temperature to 30 °C promoted the production of Fe(VI), and the change in the concentration of Fe2+ in electroplated solution showed little impact on Fe(VI) generation. However, the addition of additives inhibited Fe(VI) generation. As well, an effective removal of cyanide was achieved using on-line production of Fe(VI), comparable to that by NaClO and higher than that by other traditional oxidants containing H2O2, O3, and KMnO4. This study would provide an simple and promising iron anode for efficient production of Fe(VI) by electrochemical method.