Investigating electrode arrangement and anode role on dye removal efficiency of electro-peroxone as an environmental friendly technology

Electro-peroxone system is a novel environmental friendly technology which attracts so much attention. This process is based on reaction of hydrogen peroxide generated through electrochemical process with ozone to produce hydroxyl radicals. In this study effects of electrode arrangement, anode surface area and position compare to cathode electrodes were investigated for the first time on dye removal efficiency of electro-peroxone in a baffled reactor. Oxidation state was also used to investigate degradation of Acid Orange 7 by-products. According to the results, electrodes arrangement and increasing the ratio of the anode to cathode surface area improved the performance of the electro-peroxone process. However placing anode electrode before or after cathode electrodes had no effect on dye removal efficiency. This process, using 8 KWh per kg of removed dye, was able to remove 99% of Acid Orange 7 after 10 min with high initial concentration of 500 mg/L, anode to cathode ratio of 6:6, current of 0.5 A, ozone flow rate of 0.8 L/min, electrolyte concentration of 0.1 M, pH of 7.7 and circulation flow of 8.5 L/min. COD and TOC removal efficiency were 58% and 46% at the mentioned time that was reached to 98% and 92% after 60 min, respectively. Based on COD and TOC variations, the oxidation state altered from -8 to 3 after 60 min, indicating dye decomposition and degradation with high initial concentration of 500 mg/L into the simpler and less toxic compounds such as fumaric and oxalic acids.