Efficient photocatalytic inactivation of Microcystis aeruginosa by a novel Z-scheme heterojunction tubular photocatalyst under visible light irradiation.

The design of a photocatalyst for efficient algal inactivation under visible light is essential for the application of photocatalysis to the control of harmful algal blooms. In this study, a novel Z-scheme heterojunction tubular photocatalyst, AgO@PG, was synthesized by chemically depositing silver oxide compounded with P-doped hollow tubular graphitic carbon nitride for the photocatalytic inactivation of Microcystis aeruginosa (M. aeruginosa). The photocatalytic algal inactivation experiments showed that the photocatalytic activity of AgO@PG was influenced by the ratio of the composition of the obtained materials. The optimal algal inactivation efficiency was observed when using AgO@PG-0.4 at a dosage of 0.2 g/L. It was able to achieve a 99.1 % M. aeruginosa inactivation at an initial concentration of 4.5 × 10 cells/mL following 5 h' visible light irradiation. During the process, the cell membrane permeability and cell morphology changed. Furthermore, under the constant attack of superoxide radicals and holes caused by AgO@PG, the superoxide dismutase, glutathione and malondialdehyde of algae cells increased during the experiments to alleviate oxidative damage. Eventually, the antioxidant system of algae cells was destroyed. To further validate the potential application of AgO@PG-0.4 in real algal bloom environment, an experiment in real water samples was carried out. Overall, the AgO@PG-0.4 as an efficient photocatalyst has a promising potential for emergency treatment measures to alleviate algal blooms.