Enhanced Mediated Electron Transfer Pathway of Peroxymonosulfate Activation Dominated with Graphitic-N for the Efficient Degradation of Various Organic Contaminants in Multiple Solutions

Persulfate activated by carbon catalysts raised tremendous attention as a promising approach for degrading organic contaminants because the nonradical species produced can resist the interference of background substances. However, due to the complex and diverse structures of carbon catalysts, the reported peroxymonosulfate (PMS) activation mechanisms are varied. Herein, we used fabricated N-doped carbon nanotubes with a simple one-dimensional structure as a model catalyst to reveal the nature of PMS activation by carbon catalysts. The graphitic-N was identified as the active center to play a dominant role via structure–activity relationship analysis and density functional theory (DFT). Moreover, electron paramagnetic resonance, radical scavenging tests, and in situ Raman spectra demonstrated that the generated common reactive oxygen species did not contribute to carbamazepine (CBZ) degradation, but the electron transfer process directly oxidized the organic. Fortunately, the direct electron transfer pathway could quickly and simultaneously degrade various organics (including CBZ, sulfamethoxazole, bisphenol A, diclofenac, and tetracycline). In addition, the nature of degradation differences of various organics was revealed through the Fukui function calculated by DFT. This work revealed the mechanism of PMS activation by graphitic-N to produce mediated electron transfer pathways and provided an insight into the decomposition difference of various organic contaminants.