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.