Synergistic electron transfer in MnOX-embedded hydrochar composite for efficient peroxymonosulfate activation toward degradation of refractory florfenicol in water

Catalytic activation of peroxymonosulfate (PMS) by transition metal oxide is an effective strategy for water pollution remediation. However, the application of manganese oxides (MnO X ) is hampered by particle agglomeration and manganese ions leaching during PMS activation process, which compromise catalytic efficiency and pose environment risks. To address these limitations, MnO X -embedded hydrochar composite (HC P -Mn) was synthesized via hydrothermal-co-calcination method, utilizing hydrochar as support matrix to mitigate MnO X agglomeration and metal leakage. Refractory antibiotic florfenicol and sulfamethoxazole were used as target pollutants to assess HC P -Mn’s removal efficiency in peroxymonosulfate (PMS) activation system. Crucially, this work provided a deep insight into mechanism of PMS catalytic activation by HC P -Mn, particularly synergistic interplay between MnO X and hydrochar. Comprehensive experimental and material characterization revealed that delocalized π-electron and carbonyl groups on hydrochar enhanced electron transfer, which could directly react with PMS and strengthen dual redox circulation of Mn(II)/Mn(III)/Mn(IV) constructed by MnO X , this synergy dramatically boosted production of sulfate radical (SO 4 ‧− ) and hydroxyl radical (‧OH) via PMS activation. Consequently, HC P -Mn exhibited a reaction rate 6.9-fold higher than manganese-free hydrochar, achieving > 90 % removal of both antibiotics in 60 min. Furthermore, HC P -Mn demonstrated exceptional robustness, influence of co-existing anions and pH variations on its removal efficiency were relatively limited, enabling effective removal in real water matrices and mixed- systems. Critically, HC P -Mn exhibited good chemical stability for controllable manganese leaching and over 80 % removal efficiency after five consecutive reaction cycles. This work integrated concept of π-electron, carbonyl groups and manganese’s valence circulation for promoting PMS activation, presented a feasible hydrothermal-co-calcination method to fabricate efficient and stable MnO X -embedded hydrochar composite, synergistic electron-transfer mechanism was verified and significant potential strategy for practical antibiotic treatment in water was proposed.