Peroxymonosulfate activation by nitrogen-doped herb residue biochar for the degradation of tetracycline

Biochar is an environmentally friendly material with potential applications in water purification. In this study, herb residue nitrogen-doped biochar (N-BC) was fabricated and used to activate peroxymonosulfate (PMS). Characterization and density-functional theory (DFT) studies were conducted to explore the influence of nitrogen doping. Radical scavenging activity and electron paramagnetic resonance (EPR) spectroscopy revealed that nonradical singlet oxygen (1O2) is the main reactive oxidative species. Additionally, pyridinic-N was shown to play a pivotal role in the 1O2-dominated pathway. Three possible degradation pathways were proposed based on the identified degradation intermediates. Batch experiments confirmed that N-BC showed excellent catalytic performance and reusability. The best condition for tetracycline (TC) degradation efficiency (>99%) in 60 min was obtained when the dosage of N-BC was 1 g/L and the concentration of PMS was 5 mM. Furthermore, N-BC showed approximately 65.5% degradation efficiency within 4 cycles. Furthermore, the toxicity of degradation intermediates was examined using ECOSAR and T.E.S.T procedures. This study brings forth a feasible strategy to synthesize biochar. Furthermore, the proposed approach will facilitate the use of biochar in water purification.

Automated summary

In this study, nitrogen-doped biochar from herb residue was fabricated and used for peroxymonosulfate activation. The influence of nitrogen doping was explored through characterization and density-functional theory (DFT) studies. The nonradical singlet oxygen (1O2) was identified as the main reactive oxidative species, with pyridinic-N playing a pivotal role in the 1O2-dominated pathway. Three degradation pathways were proposed based on identified intermediates. Batch experiments confirmed the excellent catalytic performance and reusability of nitrogen-doped biochar. The proposed strategy provides a feasible approach for biochar synthesis and promotes its application in water purification.