Heterogeneous interfacial photocatalysis for the inactivation of Karenia mikimotoi by Bi2O3 loaded onto a copper metal organic framework (Bi2O3@Cu-MOF) under visible light

Numerous studies have shown that Karenia mikimotoi (K. mikimotoi) is the main toxic red tide algae in the ocean and photocatalytic technology has gradually been considered to be an effective way to inactivate harmful algae. In this study, a Bi2O3@copper metal organic framework (Cu-MOF) was successfully prepared by loading Bi2O3 on a Cu-MOF for inactivation of K. mikimotoi under visible light. The band gap of Bi2O3@Cu-MOF decreased from 2.57 eV to 2.33 eV with the loading of Cu-MOF, which increased the absorption of visible light. The specific surface area of Bi2O3@Cu-MOF was 276.604 m2/g, and the mesoporous pore size was reduced to 4 nm. When n (Cu2+): n (Bi3+) was 2: 1, Bi2O3@Cu-MOF-1 (60 mg/L) showed better photocatalytic activity under visible light irradiation for 4 h, and 96.35 % of K. mikimotoi was inactivated. The content of the two chlorophylls decreased by approximately 2 mg/L after 4 h of photocatalysis, the soluble protein decreased from 0.166 mg/L to 0.039 mg/L, and the antioxidant system was also damaged. The main free radicals were shown to be O2− and OH while the survival rate of algae cells increased by 8.273 % and 6.273 %, respectively. MOF-coupled photocatalysts have great potential for the photocatalytic treatment of harmful algae.