Coupling cathodic Electro-Fenton reaction to membrane filtration for AO7 dye degradation: A successful feasibility study

This work evidences the interest of coupling advanced oxidation process (Electro-Fenton reaction) to dynamic filtration technology, using a tubular electrochemically reactive carbon graphite membrane, acting as cathode. This original coupling would be ideally adapted to confine organic pollution while achieving the complete degradation of refractory molecules from wastewater (domestic or industrial). The investigation was carried out using Acid Orange 7 (AO7) as a model pollutant. The electrochemical behavior of the membrane was firstly characterized in batch reactor in term of cathodic reactivity, for H2O2 selective production (in situ production from air supply followed by catalyzed ●OH generation). The influence of various parameters was studied to mark out the experimental domain to be investigated in a dynamic cross-flow reactor for AO7 degradation. In the latter case, a 23 full factorial design of experiments was used to screen the effect of operating conditions on two target responses: AO7 degradation efficiency (%) and kinetic constant value. Results showed that interactions effects between pH, current density and catalyst concentration influenced the AO7 degradation efficiency significantly. Moreover, better kinetic performances were obtained under dynamic filtration conditions, compared to a batch reactor. HPLC–MS analyses enabled elucidating at least six by-products formed throughout the process.