Enhanced photocatalytic disinfection of E. coli 8099 using Ag/BiOI composite under visible light irradiation

In this study, an effective photocatalytic disinfection of E. coli 8099 using Ag/BiOI composites under visible light irradiation (λ > 420 nm) was studied. The nanostructured Ag/BiOI composites were synthesized in the presence of ethylene glycol by a solvothermal process and subsequent photodeposition method. The prepared Ag/BiOI photocatalysts were characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), energy dispersive spectrometer (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectra (DRS) measurement. The experimental results showed that the photocatalytic disinfection efficiency of E. coli (∼5 × 107 cfu mL−1) using 2.09%Ag/BiOI was almost 99.99% within 10 min irradiation, and significantly higher than that of BiOI. The determination of cell structure destruction by TEM microscopy and the measurement of released K+ further confirmed that the cell membranes of E. coli were ruptured in the photocatalytic disinfection. It was found that the deposited Ag can facilitate the surface-adsorbed O2 to scavenge the photogenerated electrons. The main active species OH for the photocatalytic disinfection performance of E. coli   was produced by two pathways, that is, hvb+ oxidized water molecules to form OH (oxidative pathway), and O2 captured the photogenerated electron to generate O2- and subsequently produce OH (reductive pathway).

► Photocatalytic disinfection of E. coli using Ag/BiOI under visible light was studied.
► Ag/BiOI had a higher photocatalytic disinfection activity than BiOI under visible light.
► Deposited Ag can facilitate surface-adsorbed O2 to scavenge photogenerated electrons.
► OH was the reactive species for photocatalytic disinfection performance of E. coli.