Irradiation-dependent properties, photodegradation dynamics, and molecular evolution mechanism of biochar-derived dissolved black carbon

Tingting Li; Fanhao Song; Mingqi Ruan; Yuhan Cao; Yao Zhao; Weiying Feng; Nuo Chen; Jin Hur; Fazhi Xie; Fengchang Wu

doi:10.1016/j.jhazmat.2025.139041

Irradiation-dependent properties, photodegradation dynamics, and molecular evolution mechanism of biochar-derived dissolved black carbon

J Hazard Mater. 2025 Jun 23:495:139041. doi: 10.1016/j.jhazmat.2025.139041. Online ahead of print.

Authors

Tingting Li¹, Fanhao Song², Mingqi Ruan³, Yuhan Cao⁴, Yao Zhao¹, Weiying Feng⁵, Nuo Chen⁶, Jin Hur⁷, Fazhi Xie⁶, Fengchang Wu⁸

Affiliations

¹ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
² State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; School of Materials Science and Chemical Engineering, Anhui Jianzhu University, Hefei 230601, China.
³ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
⁴ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; College of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China.
⁵ School of Materials Science and Engineering, Beihang University, Beijing 100191, China.
⁶ School of Materials Science and Chemical Engineering, Anhui Jianzhu University, Hefei 230601, China.
⁷ Department of Environment and Energy, Sejong University, Seoul 05006, South Korea.
⁸ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China. Electronic address: wufengchang@vip.skleg.cn.

PMID: 40578197
DOI: 10.1016/j.jhazmat.2025.139041

Abstract

Photochemistry controls the fate of dissolved black carbon (DBC) in aquatic environments, often leading to negative environmental impacts. However, the dynamic changes in DBC components during photodegradation reactions remain largely unexplored. Herein, we propose a novel photodegradation mechanism for DBC components by evaluating their irradiation-dependent properties, photodegradation dynamics, and molecular evolution using high resolution mass spectrometry and spectroscopy combined with two-dimensional correlation, inter sample ranking, and molecular networking analyses. Lignin-like and condensed aromatic molecules were predominant groups in DBC. As irradiation time increased, the functional groups in DBC displayed a sequential response of O-H stretching of phenolic > C-O stretching of alcohols/ethers/carbohydrates > C-H stretching of alkenes/(-COO stretching of carboxylic acids > CO of amide in proteins). DBC molecules transformed from unsaturated and oxidized molecules to saturated and reduced molecules during irradiation, as revealed by the chemical transformation networks of unique molecules. Components with fulvic-like fluorescence, along with lignin-like and condensed aromatic molecules, were identified as photo-labile fractions during photodegradation, while saturated molecules could play an important role in the photodegradation reaction (e.g., bond cleavage and photooxidation) of photo-stable fractions. These findings enhance our understanding of the environmental behaviors of DBC in ecosystems.

Keywords: Evolution mechanism; Molecular dynamic; Oribitrap mass spectrometry; Photodegradation reactivity; Pyrogenic organic matter.