New architecture of a variable anode for full-time efficient electrochemical oxidation of organic wastewater with variable Cl⁻ concentration

The variable composition in wastewater makes the electrochemical oxidation (EO) treatment method difficult to maintain its full-time high efficiency. In this study, the Cl⁻ concentration was investigated as the first key variable factor. A magnetically assembled electrode (MAE) architecture with flexibility and variability was utilized to treat such variable organic wastewater. The main electrode of MAE, i.e., Ti/Pb₃O₄ anode offered the MAE with the high chlorine evolution ability and stability at high NaCl concentration, while the auxiliary electrodes of MAE, i.e., Sb-SnO₂ coated magnetic particles (Fe₃O₄/Sb-SnO₂), provided the MAE with sufficient EO ability at low NaCl concentration. The degradation experiments on azo dye and phenol using MAE with different loading amount of Fe₃O₄/Sb-SnO₂ were carried out. The results provided a design rule in adjusting the optimized modular components for achieving higher EO efficiency under different Cl⁻ concentrations. The relationships between MAE's surface composition/structure, electrochemical properties, degradation efficiency and Cl⁻ concentration were further revealed. Finally, the operating mechanism of the MAE was discussed and verified.