Oxidation/mineralization of AO7 by electro-Fenton process using chalcopyrite as the heterogeneous source of iron and copper catalysts with enhanced degradation activity and reusability

In the current study, the mineralization of AO7 has been studied by a novel electrochemical advanced oxidation process (EAOP) consisting of the electro-Fenton (EF) oxidation using chalcopyrite as the heterogeneous catalyst. In this process, chalcopyrite (CP) powder was employed as the source of Fe2+ and Cu2+ co-catalysts, instead of a soluble iron salt which is used in classic EF. This new process, called here as CP-EF, was able to remove 95% TOC of AO7 under an optimum experimental condition, while the removal of only 80% TOC was observed at the optimal classic EF treatments. On the other hand, a comparative study was carried out between the CP-EF and CP-PEF processes showed the superiority of heterogeneous PEF for decolorization AO7. To test the stability and reusability of our chalcopyrite based heterogeneous catalyst, leaching and cyclic experiments were carried out, based on which the catalyst was found to be reusable with a reduction of 95% in TOC removal after 6 h of electrolysis. Although both processes were effective for the treatment of AO7, the possibility of reusing the catalyst in the heterogeneous EF process justifies its economic viability in comparison with the classic electro-Fenton process. Ion chromatography analysis confirmed the release of NO3- and NH3+ ions during the AO7 mineralization.