Accelerated Fe(II) regeneration and enhanced 1O2 production for antibiotic degradation on three-dimensional electro-Fenton filter

Abstract

The removal of emerging contaminants, particularly antibiotics, has garnered increasing attention. Heterogeneous Fenton processes are highly efficient in degrading such contaminants but are limited by the slow regeneration of Fe(II) species and the short lifespan of hydroxyl radicals (•OH). In this study, a three-dimensional electro-Fenton filter (3D-EFenF) reactor was developed to accelerate Fe(II) regeneration and the corresponding contaminant degradation. Granular activated carbon uniformly impregnated with nano-Fe₃O₄ catalysts served as the packing material, enabling synergistic pollutant adsorption and enhanced electron transfer. The system achieved complete removal of sulfadiazine (10 mg L⁻¹) within 2 min, exhibiting a reaction rate constant of 2.51 min⁻¹, 5.6-fold higher than that of the Fenton filter without an electric field (3D-FenF, 0.45 min⁻¹). Metal valence state analyses revealed that the external electric field significantly accelerated electron transfer, facilitating the regeneration of surface Fe(II) species and enhancing the Fenton-like reaction. Furthermore, singlet oxygen (¹O₂) production was markedly increased under the electric field. The 3D-EFenF reactor exhibited broad applicability in degrading various emerging pollutants, including sulfamethoxazole, ofloxacin, carbamazepine, and acetochlor, while maintaining long-term operational stability. This work provides valuable insights into the design of high-performance water treatment reactors for the effective removal of emerging contaminants.