Effective E. coli inactivation of core-shell ZnO@ZIF-8 photocatalysis under visible light synergize with peroxymonosulfate: Efficiency and mechanism

How to utilize inexhaustible solar light as a means of disinfection technology for its cheap and green remains a challenge. In this work, core-shell ZnO@ZIF-8 was synthesized and used for bacterial inactivation synergizing with peroxymonosulfate (PMS) under visible light irradiation. It took 50 min to achieve thorough sterilization for 7.5-log Escherichia coli (E. coli) cells in vis/PMS/ZnO@ZIF-8 system, compared with that 4.5-log reduction completed in vis/PMS/ZnO system under the same conditions. The enhanced photocatalytic disinfection mechanisms of fabricated ZnO@ZIF-8 were investigated by UV-vis diffuse reflectance spectra, electrochemical impedance spectra and Mott-Schottky plots. The promoted bactericidal efficiency was attributed to higher charge-separation efficiency and stronger oxidation ability of photo-generated holes. Moreover, it was found that O-1(2) and (OH)-O-center dot induced bacterial cell lesion process, and the former was the main active species. The external reactive oxygen species (ROS) caused a series of cell wall damage, intercellular ROS up-regulation and genome DNA unwinding, finally resulted in irreversible bacterial death. A two-route mechanism in vis/PMS/ZnO@ZIF-8 system was proposed, in which the generation of O-1(2) was supposed as the product of the oxygen oxidation of photo-generated holes and PMS dissociation. Our work is expected to provide advanced information about a low-cost water disinfection technology of visible light photocatalysis. (C) 2021 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.