Inactivation of Microcystis aeruginosa under visible light by Bi5O7I/g-C3N4 photocatalyst: Performance and optimization

The adsorption and oxidation of the photocatalysts are extremely significant for the deactivation of algae, which is the emphasis of this article to solve the issue of HABs in an environmentally friendly approach. BOI/CN-40 can remove 99.13 % of algae in 6 h under visible light, which is mainly attributed to the adsorption (suitable BET and positively charged), the strong oxidation of ROS (construction of Z-scheme heterojunction). And the optimization of KMnO4 can significantly improve the algae removal efficiency (complete removal within 3 h), which might have a weakening effect on low-activity algae. The decreases of superoxide dismutase, malondialdehyde and the rise of catalase during the photocatalysis treatment of algal cells by BOI/CN-40 resulted in the collapse of the antioxidant system. Meanwhile, the rupture of algal cells resulted in the release of large amounts of important ions (K+, Ca2+, and Mg2+), and the photosynthetic system was disrupted by the decrease in chlorophyll a and algal bile protein content. In summary, as a stable and efficient photocatalyst, Bi5O7I/g-C3N4 has a mitigating effect on harmful algal blooms.