Efficient destruction of pathogenic bacteria with AgBr/TiO2 under visible light irradiation

The photocatalytic inactivation of pathogenic bacteria in water was investigated systematically with AgBr/TiO2 under visible light (λ > 420 nm) irradiation. The catalyst was found to be highly effective for the killing of Escherichia coli, a Gram-negative bacterium, and Staphylococcus aureus, a Gram-positive bacterium. The decomposition of the cell wall and cell membrane was directly observed by TEM and further confirmed by K+ leakage from the inactivated bacteria. A possible cell damage mechanism by visible light-driven AgBr/TiO2 is proposed. In addition, the effects of pH, inorganic ions on bacterial photocatalytic inactivation were investigated. The electrostatic force interaction of the bacteria–catalyst is crucial for the efficiency of disinfection. Moreover, AgBr/TiO2 supported on porous nickel showed much higher bactericidal activity than fixed P25 TiO2 under visible or near UV light irradiation.