Photocatalytic Degradation of Triazine Herbicides in Agricultural Water Using a Fe3O4/SiO2/TiO2 Photocatalyst: Phytotoxicity Assessment in Pak Choi

The triazine herbicides simetryn and prometryn may cause damage to nontarget crops due to persistent contamination of agricultural water. Photocatalysis is a promising technology for the degradation of agricultural pollutants. This study provides the first systematic integration of photocatalytic herbicide degradation with live plant bioassay validation using cost-effective Fe₃O₄/SiO₂/TiO₂ magnetic photocatalysts synthesized by a simple coprecipitation method suitable for large-scale production. The phytotoxicity of herbicide-containing water was evaluated using pak choi, a crop sensitive to triazines. Both herbicides were completely decomposed in water within 240 min after UV irradiation, and their phytotoxicity also disappeared. In the plant toxicity evaluation, prometryn exhibited temporary high toxicity exceeding that of the untreated 10 ppm solution during the photodegradation process. In previous photocatalyst studies, evaluations relied on either chemical analysis or biological tests. In this study, we developed a new rapid toxicity screening technique using plant seedlings and established a safety evaluation protocol integrating chemical analysis and plant toxicity tests. This method represents the first approach to comprehensively evaluate the safety of agricultural water.