Efficient Photocatalytic Elimination of Imidazolinone Herbicides by Bismuth-Based Photocatalyst BiOIO₃

Imidazolinone herbicides such as imazethapyr (IMT) pose potential ecological risks due to their high mobility and ecotoxicity. This study synthesized the bismuth-based photocatalyst BiOIO₃ via a facile hydrothermal method and systematically characterized its physicochemical properties. BiOIO₃ features a 2D lamellar structure, pure phase composition, and a built-in internal polarization electric field that efficiently separates photogenerated electron-hole pairs. Photocatalytic experiments exhibited that BiOIO₃ achieved 84.5% elimination of IMT, with a rate constant 66 times higher than that of TiO₂ (Rutile). Mechanistic studies revealed that photogenerated electrons (e^-), holes (h⁺), and superoxide radicals (·O₂^-) are the primary reactive species. HPLC-MS/MS identified key intermediates, and QSAR-based toxicity prediction showed reduced mutagenicity for most intermediates. Importantly, BiOIO₃ effectively eliminated five imidazolinone herbicides simultaneously. This work highlights BiOIO₃ as a promising photocatalyst for efficient and practical remediation of imidazolinone herbicide-contaminated water.