Mn doped nitrogen containing carbon activating peroxymonosulfate for enhancing sulfadiazine degradation via single oxygen pathway: Performance and mechanism

In this work, manganese <bold>(</bold>Mn) with different contents doped CNs (CNs-Mn) was prepared via the thermal polymerization of the mixture of melamine, beta-lactose and manganese sulfate and used as peroxymonosulfate (PMS) activator for sulfadiazine (SD) degradation. The optimum CNs-Mn(ii) delivered admirable PMS activation efficiency toward SD degradation and the contents of oxidized N and Mn2+ in catalysts displayed strongly positive correlation with SD degradation constant. Electron paramagnetic resonance (EPR) and quenching experiments revealed that the content of generated O-1(2) species was higher than other radicals and O-1(2) dominated SD degradation in the CNs-Mn(ii)/PMS system. The density functional theory (DFT) calculation analysis revealed a novel direct evolutionary pathway of O-1(2) formation, that is the cleavage of S-O and O-H of PMS lead to two O atoms to form O-1(2). Furthermore, CNs-Mn(ii) displayed good stability, anti-interference ability and performed well in the wide pH range of 4.5 similar to 9.5. This study would give new insights into O-1(2) generation mechanism and essential atomic-scale understanding of the roles of oxidized N and Mn species in O-1(2) generation during Mn doped N containing carbon activating PMS process, as well as develop one new strategy to promote O-1(2) generation efficiency.