Plasmon-Induced Inactivation of Enteric Pathogenic Microorganisms with Ag−AgI/Al2O3 under Visible-Light Irradiation

• Published in: Environmental science & technology 2010-09, Vol.44 (18), p.7058-7062
• Main Authors: Hu, Xuexiang, Hu, Chun, Peng, Tianwei, Zhou, Xuefeng, Qu, Jiuhui
• Format: Article
• Language: English
• Subjects: Aluminum Oxide - pharmacology; Catalysis - drug effects; Catalysis - radiation effects; Disinfection; Enterobacteriaceae - drug effects; Enterobacteriaceae - pathogenicity; Enterobacteriaceae - radiation effects; Escherichia coli - drug effects; Escherichia coli - radiation effects; Humans; Hydrogen-Ion Concentration - drug effects; Hydrogen-Ion Concentration - radiation effects; Iodides - pharmacology; Ions; Kinetics; Light; Microbial Viability - drug effects; Microbial Viability - radiation effects; Remediation and Control Technologies; Rotavirus - drug effects; Rotavirus - radiation effects; Shigella - drug effects; Shigella - radiation effects; Silver - pharmacology; Silver Compounds - pharmacology; Time Factors; Virus Inactivation - drug effects; Virus Inactivation - radiation effects
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es1012577

The plasmon-induced photocatalytic inactivation of enteric pathogenic microorganisms in water using Ag−AgI/Al2O3 under visible-light irradiation was investigated. The catalyst was found to be highly effective at killing Shigella dysenteriae (S. dysenteriae), Escherichia coli (E. coli), and human rotavirus type 2 Wa (HRV-Wa). Its bactericidal efficiency was significantly enhanced by HCO3 − and SO4 2− ions, which are common in water, while phosphate had a slightly positive effect on the disinfection. Meanwhile, more inactivation of E. coli was observed at neutral and alkaline pH than at acid pH in Ag−AgI/Al2O3 suspension. Furthermore, the effects of inorganic anions and pH on the transfer of plasmon-induced charges were investigated using cyclic voltammetry analyses. Two electron-transfer processes occurred, from bacteria to Ag nanoparticles (NPs) and from inorganic anions to Ag NPs to form anionic radicals. These inorganic anions including OH− in water not only enhanced electron transfer from plasmon-excited Ag NPs to AgI and from E. coli to Ag NPs, but their anionic radicals also increased bactericidal efficiency due to their absorbability by cells. The plasmon-induced electron holes (h+) on Ag NPs, O2 •−, and anionic radicals were involved in the reaction. The enhanced electron transfer is more crucial than the electrostatic force interaction of bacteria and catalyst for the plasmon-induced inactivation of bacteria using Ag−AgI/Al2O3.