Singlet oxygen-dominated non-radical oxidation pathway for 2,4-Dichlorophenol degradation over CeO2 coated carbon fibers

CeO2 was uniformly coated onto the surface of carbon fibers (CF) and the resulting CeO2@CF was employed for the activation of peroxymonosulfate (PMS) to degrade 2,4-Dichlorophenol (2,4-DCP). Under the initial conditions of a PMS concentration of 10 mmol/L, pH range of 3 to 9 and a CeO2@CF mass concentration of 0.1 g/L, the system achieved complete degradation of 50 mg/L of 2,4-DCP with high mineralization efficiency within 60 min. Additionally, the CeO2@CF/PMS system showed high efficiency in the presence of coexisted anions (HCO3-, CO32-, SO42-, Cl-) and exhibited excellent purification capability for actual coking wastewater. Combined with characterization analyses (SEM-EDS, XRD, Raman, XPS, and EPR), degradation experiments and radical quenching experiments, the physicochemical properties of the prepared catalyst and the 2,4-DCP degradation mechanism were explored. Results revealed that CeO2 was uniformly coated on the CF surface, maintaining a regular framework structure. During this process, Ce4+ in CeO2 was reduced to Ce3+, resulting in numerous electron-rich oxygen vacancies forming inside CeO2@CF. Furthermore, the CeO2 coating increased the amount of oxygen-containing groups (C=O) on the surface of CF and graphite defects. In the CeO2@CF/PMS system, center dot O-2(-) and O-1(2) were generated at the active sites of the oxygen vacancies (Vo) and C=O with O-1(2) dominated non-free radical pathway and played a notable role in the 2,4-DCP degradation process.