Enhanced electro-Fenton oxidation in flow-through system with PES/FeOCl@CNT cathode: Nano-confined and dimensional effects

Nano-confinement has been identified as a powerful approach to boost catalytic performance and refine reaction pathways. In the present study, a flow-through electro-Fenton (E-Fenton) system was constructed with Ti mesh as anode and polyethersulfone (PES) membrane deposited with FeOCl@CNT as cathode for organic compounds degradation. The effects of different CNT dimensions (5 nm and 50 nm) with FeOCl in and out of the tube on degradation efficiency and the generation of reactive oxygen species (ROSs) have been investigated. TEM, EDS, XRD, and BET have been applied for material characterization, and results showed that FeOCl was synthesized successfully and confined in CNTs with dimensions of 5 nm and 50 nm, respectively. Systems with FeOCl@CNTs deposited on PES membrane (PES/FeOCl@CNT) were constructed, and their degradation efficiency for methylene orange (MO) have been compared. Compared with unconfined system, confined system exhibited excellent MO removal efficiency which was higher than 90 % across pH from 3 to 7. Quenching experiments and EPR analyses revealed that 1 O₂ was the dominant ROSs which occupied 70.95 % in FeOCl-in-CNT5 and 49.72 % in FeOCl-in-CNT50, respectively. All these results demonstrated that the E-Fenton flow-through system with PES/FeOCl@CNT cathode system has excellent potential for practical application for wastewater treatment with organic pollutants.