Preparation of Soybean Dreg-Based Biochar@TiO₂ Composites and the Photocatalytic Degradation of Aflatoxin B₁ Exposed to Simulated Sunlight Irradiation

Aflatoxin B₁ (AFB₁) is a highly toxic carcinogen severely harmful to humans and animals. This study fabricated SDB-6-K-9@TiO₂ composites via the hydrothermal synthesis method to reduce AFB₁. The structural characterization results of the photocatalytic composites showed that TiO₂ was successfully loaded onto SDB-6-K-9. The different photocatalytic degradation conditions, photocatalyst kinetics, recycling performance, and photocatalytic degradation mechanism were investigated. Photocatalysis with 6 mg of 4%SDB-6-K-9@TiO₂ in a 100 μg/mL AFB₁ solution presented a reduction of over 95%, exhibiting excellent performance, high stability, and reusability even after five cycles of photocatalytic experiments. Active species trapping experiments confirmed that holes (h⁺) played the most critical role. After structural analysis and identification of the photocatalytic degradation products, the photodegradation path and photocatalytic oxidation mechanism of 4%SDB-6-K-9@TiO₂ were postulated. The results show a new way to improve TiO₂'s photocatalytic performance, providing a certain theoretical basis for the effective AFB₁ reduction.