Photochemical reactivity of nitrogen-doped biochars under simulated sunlight irradiation: Generation of singlet oxygen

Jingjing Yang; Wen Zhu; Qian Yao; Guining Lu; Chen Yang; Zhi Dang

doi:10.1016/j.jhazmat.2020.124547

Photochemical reactivity of nitrogen-doped biochars under simulated sunlight irradiation: Generation of singlet oxygen

J Hazard Mater. 2021 May 15:410:124547. doi: 10.1016/j.jhazmat.2020.124547. Epub 2020 Nov 11.

Authors

Jingjing Yang¹, Wen Zhu¹, Qian Yao¹, Guining Lu², Chen Yang³, Zhi Dang⁴

Affiliations

¹ School of Environment and Energy, South China University of Technology, Guangzhou 510006, China.
² School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006, China.
³ School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006, China. Electronic address: cyanggz@scut.edu.cn.
⁴ School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006, China. Electronic address: chzdang@hotmail.com.

PMID: 33229271
DOI: 10.1016/j.jhazmat.2020.124547

Abstract

This study explored the photochemical activity of nitrogen-doped biochars (NCMs) by investigating their role in the degradation of sulfamethazine under simulated sunlight irradiation. NCMs with different doping amounts were prepared from corn straw and urea. Results showed that nitrogen doping can notably enhance the photodegradation of SMT rather than raw char. NCMs are of photochemical activity under visible light, which was confirmed by monochromatic light experiments. Quenching experiments, ESR, pH effect, and the influence of O₂ were carried out to explore the involved oxidation mechanism in this system. Results showed that ¹O₂ was the main reactive oxygen species. ¹O₂ was produced from O₂ by both energy transfer and electron transfer. DFT calculations showed that pyridinic N doping can decrease the energy of intersystem crossing and thus benefit the generation of ¹O₂ by triplet-triplet energy transfer. Results underscore the explicit importance of nitrogen element in photochemical reactivity of chars under simulated light irradiation even when the nitrogen content is low. It is a meaningful reminder for us to pay more attention to the assessment of the fate and transport of contaminants in the soil where it is rich in NCMs as well as the potential use of NCMs for pollutants remediation, since visible light is very abundant near the earth's surface.

Keywords: Nitrogen-doped char; Photodegradation; Singlet oxygen; Sulfamethazine; Sunlight.

Publication types

Research Support, Non-U.S. Gov't