Flow-through integration of FeOCl/graphite felt-based heterogeneous electro-Fenton and Ti4O7-based anodic oxidation for efficient contaminant degradation

Abstract

Improvement to the synergistic performance of cathodic electro-Fenton (EF) and anodic oxidation (AO) has been severely restricted by the tendency for ineffective decomposition of cathode-produced H2O2 at the non-active anode and poor OH utilization. Herein, a paired heterogeneous EF-AO flow-through system, consisting of an FeOCl-deposited graphite felt (FeOCl/GF) cathode and a Ti4O7 membrane anode, was constructed for rapid degradation of oxytetracycline (OTC). The real-time spatiotemporal distribution of H2O2 was systematically investigated and results revealed that the necessity for H2O2 diffusion was eliminating in the proposed system, thus contributing a 2.66-fold increase with respect to OTC degradation kinetics compared to the conventional homogeneous EF-AO system. Meanwhile, the flow-through configuration demonstrated significantly enhanced OH utilization with a 6.65-fold increase in the OTC degradation rate constant compared to the batch mode system. In addition, the EF-AO flow-through system demonstrated a high OTC degradation rate (>80 %) over a wide pH range from 3 to 7 and with different real water matrices. This work opens new avenues for advanced treatment of refractory wastewater using electrochemical advanced oxidation processes.