A Highly Synergistic Dual-Cathode Electro-Fenton Process with Self-Regulation of pH and Coating Stability for the Effective Degradation of Refractory Pollutants

As a result of issues related to pH control and the competition between H2O2 production and activation at the same sites, the applications of electro-Fenton (EF) pollutant remediation systems are limited. This work designed a synergistic dual-cathode EF system that exhibits self-adjustment of pH and stable electrode coatings. This system is based on using biomass as the active cathode material for H2O2 generation and the interaction between a stainless-steel mesh and FeOCl to reduce Fe3+ ions. The synergistic factor for this dual-cathode system was calculated to be 85.2%. Significantly, the production and activation of H2O2 in this composite system are unaffected by pH and the pH value can be adjusted between 9.67 and 3.7 without adding any acidic reagents. This process allows for the degradation of recalcitrant organic pollutants over the pH range of 3 to 9 without pre-acidification or challenges related to iron sludge and effluent chromaticity. Various organic pollutants, including antibiotics and organic dyes, can be effectively decomposed using this technology, which also exhibits good stability throughout 22 continuous trials over 1400 min. This work demonstrates a novel yet viable approach to highly efficient, inexpensive pollutant treatment with good reusability, a wide pH range and no iron leaching.