Insights into the multiple mechanisms of chlorophenols oxidation via activating peroxymonosulfate by 3D N-doped porous carbon

Abstract

Concern about nitrogen-doped carbon materials for pollutant removal via nonradical pathway is mounting. In this study, graphite carbon nitride (g-C3N4) was transformed into a high nitrogen-doped three-dimensional carbon material (N-CM) through the “metal template method”. The synthesized N-CM showed high efficiency in removing 2,4-dichlorophenol (2,4-DCP) via the activation of peroxymonosulfate (PMS). Under neutral condition, 2,4-DCP (0.2 g/L) was completely eliminated with 0.3 g/L PMS and 0.1 g/L N-CM900 in 30 min. Initial pH value, inorganic anions, and cycle experiments were selected to explore the availability of N-CM900/PMS. In addition, 1O2 dominated 2,4-DCP oxidation (about 60–70%), while the remaining 30–40% was contributed by the mediated electron transfer and N-CM-PMS*. Mechanism investigation suggested that graphitic nitrogen, the electron-rich ketonic groups and defects play a pivotal role in peroxymonosulfate activation. Combined with byproducts analysis, small-molecule acids, H2O and CO2 were predominant. Overall, this study unveils a novel direction for the design of high nitrogen-doped carbon materials and improves the understanding of the coexistence of multiple mechanisms in the activation of PMS by nitrogen-doped carbon materials.