Iron cobalt and nitrogen co-doped carbonized wood sponge for peroxymonosulfate activation: Performance and internal temperature-dependent mechanism

The directional regulation of oxidation capacity in the carbon-based peroxymonosulfate (PMS) activation system is a promising strategy for wastewater purification. In this work, a novel iron cobalt and nitrogen co-doped carbonized wood sponge (FeCoNCWS) was developed. A superb catalytic performance for sulfamethoxazole (SMX) degradation (∼100.0%) was obtained within 30 min in FeCoNCWS800/PMS system at 60 °C. Besides, the reactive oxygen species (ROS) contribution was verified at different reaction temperatures. Specifically, the primary roles of sulfate and hydroxyl radicals (SO₄^- and OH) in SMX removal weakened, while the secondary role of singlet oxygen (¹O₂) in SMX degradation was enhanced with the rise of reaction temperature in FeCoNCWS800/PMS system. Interestingly, defects, graphitic N and carbonyl (CO) groups were vital active sites for PMS activation to produce ¹O₂, which was facilitated at higher reaction temperature. Besides, the metal sites were identified as PMS activators for SO₄^- and OH generation, which was promoted under lower reaction temperature. The findings revealed a novel internal temperature-dependent PMS activation mechanism, which can help to regulate the oxidation capacity of PMS activation system rationally for pollutant degradation.