The inactivation effects and mechanisms of Karenia mikimotoi by non-metallic elements modified TiO2 (SNP-TiO2) under visible light

As an advanced oxidation technology, photocatalytic treatment of red tide algae pollution was potential of great research prospects. However, the most commonly used photocatalyst TiO2 can only use ultraviolet light with short wavelength because of its wide band gap. In this study, the non-metallic elements S, N and P were added into the TiO2 (SNP-TiO2) lattice by hydrothermal synthesis, and the inactivation effects and mechanisms of Karenia mikimotoi were studied under visible light. The particle size of the obtained photocatalyst was about 10 nm. There were obvious characteristic peaks at the (101) (004) (200) (105) (211) (204) interface and included NO bond, PO bond and SO bond. The incorporation of S, N and P reduced the band gap of TiO2 from 3.2 eV to 3.08 eV, which showed the integrity of the doping process. S0.7N1.4P0.05-TiO2 was full of excellent photocatalytic activity, the continuous inhibition effect was the most obvious. When exposed to 200 mg/L for 96 h, the growth inhibition rate (IR) was 81.8%. Photocatalytic process led to membrane damage of algal cells and collapse of photosynthetic system, caused oxidative stress response and accelerated algal cell inactivation. The study indicated that non-metallic elements modified TiO2 (SNP-TiO2) was full of potential of in treating red tide outbreak pollution under visible light.