Visible-light-driven photocatalytic inactivation of Escherichia coli by magnetic Fe2O3–AgBr

• Published in: Water research (Oxford) 2016-03, Vol.90, p.111-118
• Main Authors: Ng, Tsz Wai, Zhang, Lisha, Liu, Jianshe, Huang, Guocheng, Wang, Wei, Wong, Po Keung
• Format: Article
• Language: English
• Subjects: Bacteria; Bacterial inactivation; Bromides - chemistry; Catalysis; Disinfection - methods; Escherichia coli; Escherichia coli - growth & development; Escherichia coli - radiation effects; Ferric Compounds - chemistry; Hydrogen Peroxide - chemistry; Inactivation; Inactivation mechanisms; Light; Magnetic Phenomena; Magnetic photocatalyst; Oxidation; Photocatalysis; Photocatalysts; Photochemical Processes; Scavengers; Silver Compounds - chemistry; Staphylococcus aureus; Staphylococcus aureus - growth & development; Staphylococcus aureus - radiation effects; Water Purification - methods
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2015.12.022

Bacterial inactivation by magnetic photocatalyst receives increasing interests for the ease recovery and reuse of photocatalysts. This study investigated bacterial inactivation by a magnetic photocatalysts, Fe2O3–AgBr, under the irradiation of a commercially available light emitting diode lamp. The effects of different factors on the inactivation of Escherichia coli were also evaluated, in term of the efficiency in inactivation. The results showed that Fe2O3–AgBr was able to inactivate both Gram negative (E. coli) and Gram positive (Staphylococcus aureus) bacteria. Bacterial inactivation by Fe2O3–AgBr was more favorable under high temperature and alkaline pH. Presence of Ca2+ promoted the bacterial inactivation while the presence of SO42− was inhibitory. The mechanisms of photocatalytic bacterial inactivation were systemically studied and the effects of the presence of various specific reactive species scavengers and argon suggest that Fe2O3–AgBr inactivate bacterial cells by the oxidation of H2O2 generated from the photo-generated electron and direct oxidation of photo-generated hole. The detection of different reactive species further supported the proposed mechanisms. The results provide information for the evaluation of bacterial inactivation performance of Fe2O3–AgBr under different conditions. More importantly, bacterial inactivation for five consecutive cycles demonstrated Fe2O3–AgBr exhibited highly stable bactericidal activity and suggest that the magnetic Fe2O3–AgBr has great potential for water disinfection. [Display omitted] •The bactericidal ability of magnetic Fe2O3–AgBr under LED lamp was demonstrated.•The effects of various factors on bacterial inactivation by Fe2O3–AgBr were studied.•Fe2O3–AgBr stably inactivated 7-log of Escherichia coli in five repeated cycles.•Fe2O3–AgBr inactivated bacteria by oxidation of H2O2 and direct oxidation of h+.