Construction of a novel dual-cathode flow-through heterogeneous electro-Fenton system for enhanced mass transfer during H2O2 production and activation in cefoperazone degradation

Abstract

To accelerate the feasibility and practical considerations of the in situ generated H₂O₂, a sequential dual-cathode heterogeneous electro-Fenton (HEF) system was implemented for various pollutants degradation, in which an activated carbon fiber (ACF) cathode was used to produce H₂O₂ in situ and an FeOCl nanosheets loaded onto ACF felt (ACF@FeOCl) cathode was employed to accelerate reactive oxygen species (ROS) generation by activating H₂O₂. A novel flow-through dual-cathode HEF system was utilized by using an ACF cathode for H₂O₂ production and an FeOCl nanosheets loaded onto ACF felt (ACF@FeOCl) cathode for simultaneously producing and activating H₂O₂. The sequential dual-cathode system can generate 711.6 μM ^•OH via in situ produce H₂O₂ and completely degrade antibiotic cefoperazone (CFPZ) at neutral pH, achieving a 50 mg L⁻¹ CFPZ removal of 100.0 % within 60 min and TOC removal of 60.0 % within 180 min. The electron spin resonance (ESR) spectrum and radical quenching tests certified that the predominant ROS were ^•OH and ¹O₂ responsible for CFPZ degradation. Notably, over 10 cycles the degradation rate maintained at 100.0 % within 60 min, while the TOC removal efficiency only decreasing from 60.0 % to 51.6 % after 180 min. The UPLC-QQQ-MS results and density functional theory (DFT) was employed to propose reasonable degradation pathways of CFPZ. Ultimately, the toxicological simulation via ECOSAR assessment revealed that the toxicity of the intermediate products during CFPZ degradation appeared a declining trend. These findings collectively demonstrate that the ACF/ACF@FeOCl-HEF system was an efficient and cost-effective technology by in situ electrocatalytic synthesis of H₂O₂ and the activation of H₂O₂ to yield reactive oxygen species for the treatment of recalcitrant organic contaminants.