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.