Electrosynthesis of ferrate (VI) ion using high purity iron electrodes: Optimization of influencing parameters on the process and investigating its stability

This study is focused on the determination of optimum conditions for ferrate (VI) production and its stability. The effect of various operating parameters, such as NaOH concentration, current density, temperature and electrolysis duration on the yield of electrochemical ferrate (VI) ion production was investigated for high purity iron electrodes. Cyclic Voltammetry (CV) studies were carried out to characterize a process that takes place on the working iron electrode. The surface of high purity iron electrode was analyzed by Scanning Electron Microscopy (SEM). Electrosynthesized ferrate (VI) ion stability at different conditions was also investigated. Factors influencing the stability were initial ferrate (VI) ion concentration, alkalinity, temperature, and pH of the solution. Ferrate (VI) ion showed high stability at higher alkalinity, lower temperatures, increasing ferrate (VI) ion concentration and pH in the range between 9.2 and 10. Current efficiency and energy consumption were used for the optimum parameters determination for the ferrate (VI) production. According to the experiments, the optimum conditions were NaOH (as anolyte) concentration of 20 M, current density of 1.47 mA/cm², and temperature of 30 ± 1 °C with electrolysis duration of 1.5 hours. Ferrate (VI) ion solutions with contents up to 2.0 mM were produced in the electrochemical cell.