Recently, the Pesticide Application Risk Control Innovation Team at the Institute of Plant Protection, Chinese Academy of Agricultural Sciences (IPPCAAS), published a research paper titled  Visible light photocatalytic degradation of pesticides and antibiotics by H3PO4-activated biochar combined with g-C3N4: Effects, mechanism, degradation pathway, and toxicity assessment  in  Journal of Environmental Management (IF 8.0). The study developed a novel biochar-based g-C3N4 composite material to efficiently remove pesticide and antibiotic contaminants from aquatic environments, offering valuable insights into the modification of g-C3N4 and the treatment of agricultural wastewater. 

The widespread use of pesticides and antibiotics in agriculture and livestock farming has led to growing concerns over water pollution. The team synthesized a biochar-based g-C3N4 composite (PBC-g-C3N4 (0.15)) via an ultrasonic-pyrolysis method, which demonstrated a 4.4-fold increase in photocurrent density compared to pure g-C3N4 and achieved an 89.7% degradation rate of imidacloprid within 120 minutes. Reactive species generated under visible light, including singlet oxygen (¹O₂), superoxide radicals (·O₂⁻), and hydroxyl radicals (·OH), were identified as the primary contributors to imidacloprid degradation, with ¹O₂ playing the dominant role.  

Density functional theory (DFT) and ultra-high-performance liquid chromatography coupled with Q-Exactive mass spectrometry (UHPLC-Q-Exactive MS) analyses revealed three major degradation pathways for imidacloprid: N-dealkylation, oxidation, and hydroxylation. Most intermediate products exhibited significantly lower ecotoxicity to zebrafish (Danio rerio), water fleas (Daphnia magna), and green algae (Raphidocelis subcapitata) compared to the parent compound. This study provides a critical approach for utilizing agricultural waste, such as peanut shells, to prepare modified biochar that enhances the photocatalytic activity of g-C3N4 and removes pesticides effectively, antibiotics, and other contaminants from water systems.  

IPPCAAS is the leading institution of this research. Master’s student Haojie Shi and Ph.D. candidate Wei Wang are the co-first authors, with Researcher Xingang Liu and Associate Researcher Liangang Mao serving as corresponding authors. The work was supported by the National Key Research and Development Program of China for Young Scientists (2021YFD1700300) and the National Natural Science Foundation of China General Programs (32372604 and 32472616).

Source: https://doi.org/10.1016/j.jenvman.2025.124929