Investigation of the photocatalytic activity of magnetically recoverable g-C3N4/CoFe2O4/Bi2MoO6 particles for purifying tetracycline antibiotics: synthesis, characterization, ecotoxicity analysis, and plant toxicity test

Abstract

To purify water polluted by tetracycline antibiotics, a new visible light-driven magnetically recoverable photocatalyst, g-C₃N₄/CoFe₂O₄/Bi₂MoO₆, was prepared in this study, and it effectively removed tetracycline antibiotics. Its rapid recycling was achieved by external magnets, which greatly increased material utilization. After four repeated uses, the degradation rate of tetracycline antibiotics by the g-C₃N₄/CoFe₂O₄/Bi₂MoO₆ composite photocatalyst remained at a high level, and the magnetic separation performance remained stable. Subsequently, it was further discovered that the degradation mechanism of this photocatalytic system was consistent with a double Z-type mechanism, which enabled two transport channels for photogenerated electrons, and was favorable for the separation of the photogenerated electron–hole pairs and prolonged the lifetime of the photogenerated carriers. The active substances playing an important role in the photocatalytic system were ˙O₂⁻ and h⁺. In addition, the possible intermediates in the photocatalytic process were detected by GC-MS analysis, and a degradation mechanism was proposed. The ecotoxicity of the degradation products and intermediates was evaluated using the Toxicity Estimation Software Tool (TEST), and the mung bean seed cultivation test was carried out to visually and efficiently illustrate that the g-C₃N₄/CoFe₂O₄/Bi₂MoO₆ photocatalyst can effectively degrade antibiotics, with low ecotoxicity of the degradation products. This provides a new idea for the removal of organic pollutants using light energy.