A comparison of the effectiveness of TiO2 photocatalysis and UVA photolysis for the destruction of three pathogenic micro-organisms

Abstract

CopyrightItems in 'OpenAIR@RGU', Robert Gordon University Open Access Institutional Repository, are protected by copyright and intellectual property law. If you believe that any material held in 'OpenAIR@RGU' infringes copyright, please contact openair-help@rgu.ac.uk with details. The item will be removed from the repository while the claim is investigated. The mechanism of this process has been reported to involve attack by valence band generated hydroxyl radicals. In this study when three common bacterial pathogens, Escherichia coli, Salmonella enterica serovar Enteritidis and Pseudomonas aeruginosa, were exposed to TiO 2 and UVA light a substantial decrease in bacterial numbers was observed. Control experiments in which all three pathogens were exposed to UVA light only resulted in a similar reduction in bacterial numbers.Moreover exposure to UVA light alone resulted in the production of a smaller than average colony phenotype among the surviving bacteria, for all three pathogens examined, a finding which was not observed following treatment with UVA and Variants of pathogenic bacteria following UVA treatment of drinking water may represent a health hazard. As these Small Colony Variants were not observed with the UVA/TiO 2 system this potential hazard is not a risk when using this technology. It would also appear the bactericidal mechanism is different with the UVA/TiO 2 process compared to when UVA light is used alone.2

Sterilization effect of UV light on <I>Bacillus</I> spores using TiO2 films depends on wavelength

“…We reported UVA-induced oxidative damage is a major factor in the inactivation of bacteria, previously (19). The primary photocatalytic action for bacterial disinfection is also oxidative damage (27). The mechanism underlying photocatalysis, in the presence of TiO2 and Ag, is irradiation of TiO2 with UV light to produce electron-hole pairs.…”

The antagonistic and synergistic effects of temperature during solar disinfection of synthetic secondary effluent

“…It is the least effective irradiation range to damage bacterial DNA directly, but its proven efficiency [42] comes from the biological effects of internal and external ROS attacks, such as protein destruction or adducts of nucleic acid with membrane proteins with the bacterial envelope escaping key damage, toward cell inactivation [43]. One of the first attacks is the respiratory chain and the cell's potential to produce ATP (Bosshard et al, 2010) [55].…”

Dual Roles of Capsular Extracellular Polymeric Substances in Photocatalytic Inactivation of Escherichia coli: Comparison of E. coli BW25113 and Isogenic Mutants

“…Numerous studies have proven the ability of these reactive species to inactivate various kinds of pathogenic bacteria (9)(10)(11). It is widely accepted that the bactericidal effect of TiO 2 is due to the destruction of the cell envelope by ROS generated on the surface of TiO 2 photocatalysts (12).…”