Ag/CeO₂/SBA-15 hybrid catalysts for the elimination of E. coli in potable water system

Hybrid Ag/CeO2/SBA-15 mesoporous nanocatalysts were prepared and their bactericidal activity was evaluated aiming at elimination of Escherichia coli (E. coli) in the potable water system. It was found that there existed electrons transferring from Ag⁰ to CeO2 to form Ag⁺/Ag⁰ and Ce⁴⁺/Ce³⁺ couples in the heterojunction structure, which resulted from strong interaction between Ag nanoparticles (AgNPs) and highly dispersed CeO2. By increasing the Ag content from 1wt% to 3 and 5 wt% in the catalysts, the bactericidal power of Ag/CeO2/SBA-15 materials significantly enhanced in the presence of both visible and UV light, which can be explained by the increasing electrons transferring function from Ag⁰ to CeO2 under UV-visible light irradiation. A combination mechanism of E. coli deactivation was proposed where E. coli body may be simultaneously attacked by both AgNPs and Ag⁺ ions promoted by CeO2. The former may attack the cell membrane, leading to its cleavage and disruption; and the latter may be ionized and released from AgNPs to enter inside the cell, modifying its permeability and respiration, finally resulting in complete deactivation and death.