Novel insights into the relationship between the functional groups and photoactivity of biochar-derived dissolved organic matter

• Published in: Water research (Oxford) 2024-08, Vol.260, p.121892, Article 121892
• Main Authors: Zuo, Xin, Ouyang, Zhuozhi, Liao, Jinmo, Ding, Rui, Zhang, Weiwei, Zhang, Chi, Guo, Xuetao, Zhu, Lingyan
• Format: Article
• Language: English
• Subjects: Biochar-derived dissolved organic matter; Charcoal - chemistry; Electron donating capacities; Humic Substances; Molecular structure; Photodegradation; Photolysis; Reactive oxygen species; Reactive Oxygen Species - chemistry; Sewage - chemistry; Water Pollutants, Chemical - chemistry
• ISSN: 0043-1354; 1879-2448; 1879-2448
• DOI: 10.1016/j.watres.2024.121892

•Three types of BDOM have different molecular compositions and photoactivity.•Photoactivity of BDOM is highly correlated with functional groups.•Aromatic, thiol, and amino groups in BDOM affect electron and energy transfer.•Higher electron and energy transfer in BDOM contribute to the generation of ROS.•Generation of ROS in BDOM promotes the photodegradation of TC. Due to the production of a large amount of biochar, highly photoactive biochar-derived dissolved organic matter (BDOM) from different sources is released into surface water. This study investigated the molecular composition of BDOM (sludge, bamboo and stalk BDOM) using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and used tetracycline (TC) as model pollutant to investigate the relationship between molecular composition and BDOM photoactivity, specifically focusing on reactive oxygen species (ROS) production. The results indicate that the fluorescence signal intensity of humic acid-like and aromatic proteins in the plant-derived BDOM are significantly higher than that derived from sewage sludge. FT-ICR MS results also showed that plant-derived BDOM contained more CHO molecular formula. Photodegradation experiments of TC mediated by various BDOM analogues demonstrated the photoactivity is highly correlated with the components and functional groups. The electrochemical experiments and density functional theory (DFT) calculations further verified that the aromatic moiety, sulfydryl group and amino group of BDOM affected the electronic supply and energy transfer. Higher electron and energy transfer favor the reaction of BDOM with the ground state oxygen to generate ROS, thus promoting photodegradation of TC. This study provides a new basis for better assessing the ecological risks of BDOM. [Display omitted]