Silica‑assisted Fe-Mn bimetallic oxide/conductive carbon black composite in 3D electro‑Fenton system for degradation of tetracycline.

Antibiotic contamination demands efficient remediation technologies. Although three-dimensional Electro-Fenton (3D-EF) systems show promise, conventional granular electrodes suffer from rapid deactivation and poor conductivity. Herein, we report a ternary Fe-Mn composite granular electrode for tetracycline (TC) degradation. The electrode integrates three synergistic functionalities: (i) iron-manganese oxides as the primary active phase, where Fe-Mn redox synergy accelerates Fe(II) regeneration; (ii) silica incorporation to fortify the oxide layer and enhance structural stability; and (iii) conductive carbon black doping to improve electrical conductivity and electron transfer. The system achieved 95% TC removal within 120 min. Characterization confirmed the structural and electrochemical advantages, while mechanistic studies identified singlet oxygen (1O₂) as the dominant reactive species. This work provides a durable, high-performance granular electrode for practical 3D-EF treatment of antibiotic pollutants.