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

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).

Inactivation and Photorepair of Enteric Pathogenic Microorganisms with Ultraviolet Irradiation

“…coli and S. dysenteriae were inoculated into a nutrient broth medium, while S. typhimurium was maintained on tryptone soy broth (TSB) (Hu et al, 2010). HRV-Wa stocks were propagated, concentrated, and purified, using methods previously described by Jean et al (2002).…”

Visible-light-driven photocatalytic inactivation of E. coli by Ag/AgX-CNTs (X=Cl, Br, I) plasmonic photocatalysts: Bacterial performance and deactivation mechanism

“…Some researches showed that noble metal nanoparticles, such as Ag, Au and Pt, exhibited strong UV-vis absorption due to their plasmon resonance, which is produced by the collective oscillations of surface electrons [12][13][14][15][16]. Therefore, recently much more effort has been devoted to design Ag/AgX (X = Cl, Br, I) composite materials due to the surface plasmon resonance (SPR) of metallic Ag [1,[17][18][19][20], which can dramatically enhance the absorption of visible light (VL) and provide new opportunities to develop VLD photocatalysts [21].…”

Preparation and characterization of visible light-driven AgCl/PPy photocatalyst

“…Furthermore, complex composites formed by immobilizing Ag/AgX on inert supports [27][28][29] and magnetic Fe 2 O 3 [30] (Ag/AgX/suppport) or combining Ag/AgCl with other semiconductors (Ag/AgX/SC) [31] exhibited enhanced efficiency in photocatalytic degradation. In addition, these Ag/AgX/support and Ag/AgCl/SC composites also worked well in photocatalytic bactericide [32,33]. These indicate that Ag/AgXs play key roles in photocatalysis process both as a photocatalyst and a co-photocatalyst.…”