Effect of depositing silver nanoparticles on BiVO4 in enhancing visible light photocatalytic inactivation of bacteria in water

Recently, photocatalytic processes have been shown to be a promising low-cost and sustainable alternative for water and wastewater treatment. In this study Ag/BiVO4 composites were fabricated and their photocatalytic disinfection activity was tested against Escherichia coli under visible light (lambda > 420 nm). Deposition of silver nanoparticles on the surface of BiVO4 led to a significant improvement of the photocatalytic activity. Irradiation of the suspension of Escherichia coli (10(7) CFU mL(-1)) in the presence of Ag/BiVO4 resulted in the total disinfection of the cells within 3 h. The photocatalytic activity of the composite was stable in repeated runs. The disinfection study was also conducted under the tropical afternoon sun in Singapore. The significant enhancement in the photocatalytic activity of Ag/BiVO4 can be ascribed to the effect of metallic silver nanoparticles, which act as an electron trap on the surface of BiVO4 and promote the separation of photo-induced electron/hole pairs for the generation of reactive oxygen species.