One-step pyrolysis for the preparation of sulfur-doped biochar loaded with iron nanoparticles as an effective peroxymonosulfate activator for RhB degradation

In this study, sulfur-doped biochar loaded with iron nanoparticles (Fe/S-BC) was easily prepared by a one-pot pyrolysis method using anhydrous FeCl3, Na2S2O3·5H2O, and cherry stone powder as raw materials and applied to activate peroxymonosulfate (PMS) for the degradation of Rhodamine B (RhB). Fe/S0.05-BC exhibited strong activation ability with regards to PMS activation, and 0.05 g L−1 of Fe/S0.05-BC along with 0.5 g L−1 of PMS could degrade 20 mg L−1 of RhB completely in 10 min, and the high activity was retained over a wide pH range. Electron paramagnetic resonance and quenching experiments proved that sulfate radicals (SO4•−), hydroxyl radicals (˙OH) and singlet oxygen (1O2) were the main reactive oxidizing species for RhB degradation. The high activity of the catalyst was attributed to the synergistic action among the Fe nanoparticles, carbon matrixes, and doped S elements. The quick and simple synthesis method, excellent activation efficiency, low-cost, and sustainable raw materials make the Fe/S0.05-BC composite a very promising candidate for environmental remediation.