Efficient Degradation of Antibiotics by Activating Peroxymonosulfate (PMS) with Biochar (BC)-Modified FeOx under UVA-LED Irradiation

There are obvious drawbacks for the traditional treatment methods of antibiotics, such as low efficiency and high cost. In this paper, FeOx catalysts, modified with the biochar (BC) of maple leaf (FeOx@BC), were successfully prepared by the hydrothermal method. Then, the FeOx@BC was investigated to activate peroxymonosulfate (PMS) under UVA-LED irradiation for the degradation of tetracycline hydrochloride (TC). Subsequently, the changes in valence states before and after the reaction of ions were investigated by XPS spectra, and the process mechanism was presented. The results demonstrated that the TC degradation efficiency reached 96% in the FeOx@BC + PMS + UVA-LED system within 40 min, which was higher than 57% efficiency for the α-Fe2O3 + PMS + UVA-LED system. The electron transfer was promoted in the FeOx@BC + PMS + UVA-LED system due to the doping of BC. The Fe(III) was transformed into Fe(II) under UVA-LED irradiation, and Fe(II) activated continuously PMS to generate active oxygen species. Furthermore, it had excellent reusable performance and structural stability, and the degradation efficiency was still as high as 80% after five cycles. It was proved that SO4−•, •OH, O2•− and h+ participated in the degradation process of TC to different degrees by quenching experiments and EPR tests. In summary, FeOx@BC is an inexpensive, reusable and efficient catalyst.