Insights into the synergistic effect of Fe and Ce in Fenton-like reactions catalyzed by chitosan/FeOOH/CeO2 microspheres

Abstract

In recent years, significant progress has been made in the development of Fenton-like catalysts suitable for operation under neutral conditions. In this study, chitosan/FeOOH/CeO2 microspheres were developed using a straightforward coprecipitation method. The catalysts are simple to prepare, cost-effective, and suitable for large-scale production. In the presence of 60 mmol/L of H2O2, the catalysts achieved a 98% removal efficiency for 50 mg/L of OTC in simulated wastewater within 30 min at a wide pH range of 3–9. The excellent performance of the catalysts was mainly attributed to the formation of a CeO2–FeOOH heterogeneous structure resulting from the combination of CeO2 and the FeOOH matrix. In addition, the CeO2–FeOOH heterogeneous structure increased the concentration of oxygen vacancies on the surface of CeO2 and allowed the catalyst spheres to maintain a specific surface area of 103.7 m2/g even when the diameter increased to 1.73 ± 0.16 mm. Density functional theory calculation and other supporting results revealed that Ce(III) served as the primary active centers responsible for the adsorption and activation of H2O2, while Fe(II) at the heterojunction facilitated the regeneration of Ce(III). This study provides insight into the development of efficient catalysts and the fundamental mechanisms of water treatment processes.