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

Abstract

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/S_0.05-BC exhibited strong activation ability with regards to PMS activation, and 0.05 g L⁻¹ of Fe/S_0.05-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/S_0.05-BC composite a very promising candidate for environmental remediation.