Persulfate activation over B, N co-doped carbon nanotubes encapsulated with Fe3C (Fe3C@BN-CNT-x) studied for degradation of Rhodamine B

Herein, B, N co-doped carbon nanotubes encapsulated with Fe3C (Fe3C@BN-CNT-x) were synthesized via a onestep pyrolysis process, which is used to activate peroxymonosulfate (PMS) for the degradation and removal of water-soluble dye pollutants. The morphology and crystalline phase structure, elemental composition, specific surface area, pore structure, and defects of Fe3C@BN-CNT-x were subjected to comprehensive analysis and investigation through the use of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 isothermal adsorption and desorption curves, Raman spectroscopy. Fe3C@BN-CNT-0.3, the best sample, displayed the largest specific surface area, the highest ratio of Fe-Nx and BC3 centers, and most abundant defect sites. As a result, Fe3C@BN-CNT-0.3 shows the fastest and highest efficient removal of Rhodamine B (RhB), achieving 100 % degradation efficiency within 8 min. The degradation rate constant of RhB over Fe3C@BN-CNT-0.3 is as high as 0.531 min-1, which is about 5 times that of Fe3C@N-CNT. Free-radical quenching experiment and electron paramagnetic resonance (ESR) spectroscopy, as well as electrochemical voltammetry, identify the non-radical 1O2 as the dominant reactive species. Other free-radicals, such as SO4 center dot-, center dot OH, and center dot O2-, play a minor role, while electron transfer mechanism was not a significant factor in the process of degradation.