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  • Plasmon-induced inactivation of enteric pathogenic microorganisms with Ag-AgI/Al2O3 under visible-light irradiation.

Plasmon-induced inactivation of enteric pathogenic microorganisms with Ag-AgI/Al2O3 under visible-light irradiation.

Environmental science & technology (2010-08-26)
Xuexiang Hu, Chun Hu, Tianwei Peng, Xuefeng Zhou, Jiuhui Qu
ABSTRACT

The plasmon-induced photocatalytic inactivation of enteric pathogenic microorganisms in water using Ag-AgI/Al(2)O(3) 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 HCO(3)(-) and SO(4)(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/Al(2)O(3) 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, O(2)(•-), 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/Al(2)O(3).

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Silver iodide, 99%
Sigma-Aldrich
Silver iodide, 99.999% trace metals basis