Electrochemical treatment of aqueous solutions of catechol by various electrochemical advanced oxidation processes: Effect of the process and of operating parameters

- The mineralization of catechol was performed by various electrochemical processes.
- Direct anodic oxidation, electro-Fenton, oxidation by electro-generated active chlorine and coupled processes were evaluated.
- For electro-Fenton process, higher abatements were achieved with heterogeneous pyrite or chalcopyrite catalysts.
- Very high mineralizations were achieved by electro-Fenton and direct anodic oxidation.

Catechol, one of the most abundant compounds in olive mills wastewaters, which is generated in the Fenton degradation of various aromatic compounds, is a toxic, possible carcinogen, persistent pollutant and it is not readily biodegradable. Hence, its degradation requires the utilization of advanced oxidation processes (AOPs). Here, the electrochemical treatment of aqueous solutions of catechol was investigated. The utilization of various electrochemical processes, such as electro-Fenton (EF), direct anodic oxidation (AO), indirect oxidation by electro-generated active chlorine and coupled processes was investigated. Furthermore, the effect of various operating conditions (including the nature of anode for AO, the initial pH and the current density) was widely studied in order to optimize the selected electrochemical processes. For EF process, the effect of the nature of the catalyst (homogeneous FeSO4 and heterogeneous pyrite and chalcopyrite) was also analysed. It was shown that both EF and AO, under proper operating conditions, allow a very high removal of the TOC, while the indirect oxidation by electro-generated active chlorine is poorly effective. The utilization of a coupled EF-AO process allowed enhancing the abatement of both catechol ad TOC with respect to single processes.