Sustainable photocatalytic disinfection of four representative pathogenic bacteria isolated from real water environment by immobilized TiO2-based composite and its mechanism

In this study, we reported an effective visible light-assisted photocatalytic disinfection toward various representative pathogenic bacteria over a highly reusable glue-immobilized P/Ag/Ag2O/Ag3PO4/TiO2 (PAgT) system. The results showed that the PAgT photocatalyst could rapidly kill all pathogenic bacteria isolated from real water environment, including Gram-positive (+ve) (Enterococcus sp. and Staphylococcus aureus) and Gram-negative (-ve) (Escherichia coli and Salmonella), both in single and mixed bacteria system. Compared to Gram -ve bacterium, the inactivation of Gram +ve bacterium was more resistant to the photocatalytic treatment, which was mainly ascribed to their thicker peptidoglycan layers in cell walls. In addition, using silicone glue as a binder provided a strong adhesion between the solid matrix and catalyst particles thus making the immobilized PAgT highly reusable. More strikingly, it was found that the enhanced antibacterial performance of immobilized PAgT system was due to a synergistic effect of disinfection mechanism combining the improved photocatalysis on the introduction of heterojunction structure, and the mechanical stress driven from the composite sharp edge morphology. Hence, the present results of the photocatalytic disinfection toward a broad range of pathogenic bacteria, with excellent activity, stability and reusability, reveals the possibility of the developed silicone glueimmobilized PAgT in real water sterilization.

Automated summary

The study found that the P/Ag/Ag2O/Ag3PO4/TiO2 photocatalyst immobilized with silicone glue showed effective disinfection towards various pathogenic bacteria, with better performance against Gram-positive bacteria. The enhanced antibacterial activity of the immobilized PAgT system was attributed to a synergistic effect between improved photocatalysis and mechanical stress driven from the composite sharp edge morphology.