One-pot fabrication of sludge-derived magnetic Fe,N-codoped carbon catalysts for peroxymonosulfate-induced elimination of phenolic contaminants

The use of waste sludge as a precursor of catalysts for environmental applications has been encouraged during the past few years. In this study, a series of magnetic Fe,N-codoped carbon catalysts (UBC- x ) were successfully prepared by a facile one-pot pyrolysis method using Fe-rich sludge and N-rich urea as the raw materials. By carefully controlling the mass ratio of urea/dry sludge ( x  = 0–3), a significant amount of N (1–10 mass%) were incorporated, and the UBC- x catalysts, especially UBC-0.5 and UBC-0.75, could be imparted with high catalytic activity , convenient magnetic separation and high recycle stability. Phenolic contaminants like phenol and bisphenol A (BPA) could be nearly completely removed through peroxymonosulfate (PMS)-induced degradation by using UBC- x as the catalysts under a wide pH range (2–11) and with the co-existence of water constituents (chloride Cl − and sodium humate NaH, 0–50 mM). Among the several reactive oxidative species (ROS), singlet oxygen ( 1 O 2 ) was deemed as the main reactive species responsible for BPA degradation. Both Fe and N active sites contributed to the high catalytic activity of UBC- x , and their coordination made the catalysts rather stable with no significant Fe leaching under a wide pH range. Therefore, after an easy magnetic separation, the UBC- x could be recycled and reused efficiently in another BPA removal cycle. The as-synthesized magnetic Fe,N-codoped carbon catalysts provided a new route for sludge reutilization and showed potential applications in wastewater treatment .