Enhanced nitenpyram degradation by metallic carbon nitrogen composites catalyzed peroxymonosulfate: Synergistic effect of radical and nonradical pathways

Abstract

Identifying the key active site for peroxymonosulfate (PMS) activation in metallic carbon nitrogen mixtures (MCN) is essential for the optimization of catalyst preparation strategy. Herein, we utilized a pyrolysis method to fabricate MCN for peroxymonosulfate (PMS) activation. The optimal MCN − 700/PMS system showed outstanding catalytic activity for multiple pollutants, and strong resistance to pH (3–11) and complex water environment. Combined with density functional theory calculations, we confirmed the structure − function relationships between different active sites in MCN and PMS. PMS would be preferentially adsorbed on Mn5C2 and Fe2N of MCN − 700, followed by the stretch and fracture of peroxides O − O of the adsorbed PMS. The superior stability could be attributed to that MCN has a continuous N − doped carbon shell structure that promoted electron transfer and encapsulated metal components like an armor. The MCN − 700/PMS system possessed extraordinary degradation activity in complex aqueous environment and various refractory organic pollutants can be efficiently removed, exhibiting the great merits of the radical and nonradical synergistic oxidation. The findings provided new insights into the reaction mechanisms of MCN/PMS system and the rational design heterogeneous PMS systems involving the synergistic action of radical and nonradical oxidation.