Activation of peroxymonosulfate by nitrogen-doped porous carbon for efficient degradation of organic pollutants in water: Performance and mechanism

Carbon materials are becoming the first choice for activating persulfate due to their environmental friendliness, high chemical stability, and metal-free leaching. However, the preparation of efficient carbon catalyst and the in-depth analysis for persulfate activation is still insufficient. Herein, N-doped porous carbons (NPCs) were prepared by the pyrolysis of polyacrylonitrile and used to trigger peroxymonosulfate (PMS) for degrading organic pollutants in water. The results showed that the optimized NPC-700, with large specific surface area, rich pore structure, high content of pyridinic N and graphitic N, as well as excellent oxygen-containing functional groups, possessed the best performance in activating PMS to degrade methylene blue (MB) with 99.15% degradation rate in 30 min. Furthermore, the NPC-700 delivered high stability under a wide pH from 3.51 to 11.15. The radical quenching experiments and electron paramagnetic resonance (EPR) spectroscopy revealed that •OH, O2•-, SO4•- and 1O2 active species were involved in the catalytic oxidation of MB. Besides, the NPC-700/PMS system exhibited excellent degradation performance for various organic dyes, including rhodamine B, acid orange 7, and methyl orange. This study not only provides a promising metal-free catalyst for the removal of organic pollutant in water, but also promotes the sustainable development of carbon-based materials.