Study on electrochemical properties and synthesis process of ferrate(VI) solution on gray cast iron anode in concentrated alkaline solution

Abstract

The aim of the study was to compare and evaluate electrochemical properties and capability of synthesising ferrate on gray cast iron anode in 14 M NaOH and 14 M KOH solutions. Tafel polarisation showed that gray cast iron was more corroded in 14 M NaOH solution. Cyclic voltammetry spectra showed that ferrate synthesis in NaOH and KOH solutions would produce intermediate products such as iron(II), iron(III), ferromagnetic oxide, and hydroxide. The efficiency of ferrate synthesis in 14 M NaOH solution was significantly higher than that in 14 M KOH solution. The study also found that the current density of 40 mA/cm2 and electrolysis time of 9 hours were optimal condition for ferrate synthesis using gray cast iron anode in 14 M NaOH solution. In addition, the study also showed the change in the morphological structure of the anode surface after electrolysis by scanning electron microscopy (SEM) analysis method and X-ray diffraction (XRD) patterns. The results showed that there was a passive layer formed on the anode surface after a period of electrolysis.