Melamine foam derived nitrogen and boron co-doped metal-free electrode for enhanced electro-Fenton degradation of metronidazole

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2023-01, Vol.455, p.140593, Article 140593
• Main Authors: Zhao, Heng, Ma, Xiaolin, Lu, Mingjie, He, Fengting, Lin, Feifei, Zhang, Yang, Zhang, Jinqiang, Dong, Pei, Zhao, Chaocheng, Sun, Hongqi
• Format: Article
• Language: English
• Subjects: Catalytic mechanism; Heteroatom doping; Heterogeneous electro-Fenton; Melamine foam; Metal-free
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2022.140593

The reaction mechanism of electro-Fenton process with the NB/CF40 cathode. [Display omitted] •NB co-doped melamine foam derivative electrode was fabricated by a simple strategy.•NB/CF40 showed superior activity and excellent stability in heterogeneous EF system.•The B-C3-graphitic N and B-C3-pyridinic N contributed to the improved EF efficiency.•Reaction mechanism and organic pollutants degradation pathways were proposed. In this work, a melamine foam derived nitrogen (N) and boron (B) co-doped metal-free electrode was prepared by accessible method and applied in heterogeneous electro-Fenton (EF) system. Overcoming the metal ion leaching and harsh operating conditions of most transition metal electrodes, the prepared metal-free electrode (NB/CF40) possessed an excellent EF performance for degradation of metronidazole (MTZ) in a wide range of pH (3–11), maintaining great reusability even after ten runs with higher mineralized current efficiency (MCE) and lower energy consumption (EC). Significantly, the NB/CF40 has excellent decontamination performance for actual wastewater containing MTZ analyzed by quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) and three-dimensional excitation-emission matrix fluorescence spectra (3D EEMs). According to experimental results, characterization analysis and density functional theory (DFT) calculations, EF reaction mechanism by NB/CF40 cathode was proposed, in which the active sites of BCCC-graphitic N and BCCC-pyridinic N configurations contributed to the improvement of EF performance by affecting the charge density of nearby carbon framework, adsorption of O2, and desorption of *OOH. This work offers a new idea for the remediation of wastewater by the efficient metal-free EF system in a wide pH range.