Magnetic Core–Shell-Structured FeO_x/CN Catalyst Mediated Peroxymonosulfate Activation for Degradation of 2,4-Dichlorophenol via Non-Radical Pathway

In this study, a magnetic nano-FeO_x/CN core–shell-structured catalyst with a high operating stability was successfully prepared by a coordinating polymer pyrolysis strategy. It exhibited high catalytic activity in peroxymonosulfate (PMS)-based advanced oxidation processes. Under neutral and room temperature conditions, the removal efficiency of 2,4-dichlorophenol (2,4-DCP) via FeO_x/CN/PMS system reached more than 90% within 60 min, and the removal of total organic carbon reached 89% within 90 min. The key operating parameters were evaluated and analyzed. Besides, in five consecutive degradation experiments, Fe-3/CN showed high stability, low iron ion loss, and excellent magnetic separation and recovery performance, demonstrating its potential as a practical Fenton-like catalyst. The abundant and orderly N pores in the CN structure provided key conditions for the anchoring and dispersion of nano-FeO_x particles. Electron paramagnetic resonance and free radical scavenging experiments proved that ¹O₂ is the main reactive oxygen species (ROS) that causes 2,4-DCP degradation (about 76.4% of the total contribution). Combined with density functional theory, the degradation pathway of 2,4-DCP was reasonably predicted. This study provides new ideas for the design and synthesis of Fenton-like catalysts with high stability and high activity.