Abstract: To address the problems of low removal efficiency and high risk of secondary pollution of difficult-to-degrade organic pollutants in water bodies, a Mn_0.5-CN non-homogeneous catalyst was prepared by high-temperature calcination, and the efficient degradation of 4-chlorophenol (4-CP) was achieved by activating peroxymonosulfate (PMS), and the catalyst was structurally analyzed by various characterization means. The results showed that under the optimized conditions (catalyst dosage of 0.5 g/L, PMS concentration of 0.8 mmol/L, room temperature), the catalyst achieved 95.1% removal of 4-CP at 20 mg/L and 78.6% removal of total organic carbon (TOC) within 60 min. Mechanistic studies showed that the redox cycle of Mn(Ⅱ)/Mn(Ⅲ) played a dominant role in the activation process of PMS, in which single-linear oxygen (¹O₂) was the main active species, and hydroxyl radical (·OH) assisted the degradation. The catalyst maintained more than 80% degradation efficiency after five cycles of use. In addition, the system had good pH（3~11） adaptability and good environmental applicability (different water bodies and anions). This system provided an efficient, stable and environmentally friendly solution for 4-CP treatment by mineralizing pollutants through C-Cl bond breaking and aromatic ring opening reactions.

Key words: manganese-based catalysts, carbon nitride, peroxymonosulfate, 4-chlorophenol, valence cycling, degradation efficiency