Nitrogen and Boron Co-Doped Biochar-Activated Peroxymonosulfate for Degradation of Tetracycline: Performance and Mechanisms

Antibiotic residues pose a serious threat to environmental safety. In this study, nitrogen/boron co-doped biochar (NBLB) was successfully prepared using lignosulfonate, an industrial byproduct, as the precursor via a one-step impregnation–pyrolysis method. NBLB was applied to activate peroxymonosulfate (PMS) to degrade tetracycline (TC) in water. The results showed that NBLB-activated PMS degraded 93.4% of TC within 60 min, which was 42.6%, 20.4%, and 27.8% higher than those of undoped biochar, nitrogen-doped biochar, and boron-doped biochar, respectively. Additionally, the NBLB/PMS system exhibited high tolerance to common aqueous anions such as Cl − , C O 3 2 − , PO 4 3 − , NO 3 − and S O 4 2 − . BET tests indicated that the specific surface areas of undoped, N-doped, B-doped, and NBLB were 133.98, 280.22, 304.13, and 342.35 m 2 g −1 , respectively, exhibiting a significant enhancement in the specific surface area of NBLB. The co-doping of N and B constructed a hierarchical pore structure, providing an efficient dispersion platform for active sites such as C=O, BC 2 O, and pyridinic-N. Quenching experiments and EPR detection demonstrated that the degradation of tetracycline (TC) in the NBLB/PMS system followed a synergistic oxidation mechanism dominated by 1 O 2 and O 2 • − , supplemented by • OH and S O 4 • − . This study prepared high-performance nonmetallic catalysts through a solid waste resource utilization strategy, providing a green and feasible path for the treatment of antibiotic pollution.