Disinfection Kinetics and Contribution ofReactive Oxygen Species When EliminatingBacteria with TiO2 Induced Photocatalysis

摘要

Titania (TiO2) induced photocatalysis has been widely investigated and applied as a disinfectionstrategy in many industrial and clinical applications. Reactive oxygen species (ROS), including hydroxylradicals (•OH), superoxide radicals ( •−2 O ) and hydrogen peroxide (H2O2), generated in thephotocatalytic reaction process are considered to be the active components prompting the bactericidaleffect. In the present work, the kinetics of photocatalytic inactivation of Staphylococcus epidermidisand specific contributions of •OH, •−2 O and H2O2 to the bactericidal process were studiedusing two disinfection settings sutilizing photocatalytic resin-TiO2 nanocomposite surfacesand suspended TiO2 nanoparticles, respectively. In antibacterial tests against S. epidermidis with alayer of bacterial suspension on the resin-TiO2 surfaces, H2O2 was found to be the most efficientROS component contributing to the antibacterial effect. Disinfection kinetics showed a two-stepbehavior with an initial region having a lower disinfection rate followed by a higher rate regionafter 10 min of UV irradiation. By contrast, in antibacterial tests with suspended bacteria andphotocatalytic TiO2 nanoparticles, •OH and H2O2 showed equal significance in the bacterial inactivationhaving a typical Chick-Watson disinfection kinetics behavior with a steady disinfection rate.The results contribute to the understanding of the bactericidal mechanism and kinetics of photocatalyticdisinfection that are essential for designing specific antibacterial applications of photocatalyticmaterials.