Qiang Li, B Wang, Haiyu Cheng, Zhixuan Fan
ABSTRACT Advanced oxidation processes based on peroxymonosulfate (PMS) activation have attracted considerable attention for the treatment of dye‐containing wastewater. However, conventional Fe‐Co/PMS systems still suffer from limited PMS activation efficiency and poor catalyst recoverability. In this study, a magnetic CoFe 2 O 4 ‐modified hydrochar catalyst derived from wheat straw was developed for PMS activation and methylene blue (MB) degradation. Alkali modification and the introduction of an additional carbon source enriched the hydrochar with active sites and oxygen‐containing functional groups, thereby facilitating MB enrichment near the CoFe 2 O 4 active centers. Meanwhile, the supported CoFe 2 O 4 provided Fe‐Co redox sites for PMS activation and endowed the catalyst with magnetic recoverability, enabling efficient PMS‐mediated MB degradation and catalyst reuse. After optimization of the reaction conditions, the MHTC/PMS system achieved a maximum MB removal efficiency of 99.8%. After five consecutive reuse cycles, the MHTC/PMS system maintained an MB removal efficiency of 68.8% and a chemical oxygen demand (COD) removal efficiency of 60.65%. Radical quenching experiments and electron paramagnetic resonance analysis revealed that MB degradation in the MHTC/PMS system proceeded through both radical and non‐radical pathways, with SO 4 · − playing the dominant role, followed by 1 O 2 and . OH. The intermediate products and possible degradation pathways were further identified by LC–MS analysis.