Gas phase photocatalytic bacteria inactivation using metal modified TiO₂ catalysts
2013
Modesto, Olayr, Jr | Hammer, Peter | Nogueira, Raquel F Pupo
The present study describes the efficiency of heterogeneous photocatalytic reactor for the inactivation of three air born bacteria, Escherichia coli, Bacillus subtilis and Staphylococcus aureus using metal modified TiO₂ photocatalysts and blacklight irradiation. The catalysts were prepared by photodeposition of silver, palladium or iron on commercial TiO₂, immobilized on glass plates. X-ray photoelectron spectroscopy analysis was applied to determine the atomic percentage and species of each metal on the TiO₂ surface, showing that 85% of silver, 73% of palladium and 45% of iron were present in metallic form on TiO₂ surface. The plates were positioned on the inner lateral walls of a chamber through which the contaminated air flow passed for disinfection. Irradiation of bare TiO₂ resulted in 50% inactivation of E. coli while 41% and 35% inactivation of B. subtilis and S. aureus were obtained, respectively. When metal modified TiO₂ was applied, the inactivation of B. subtilis was improved to 91% using Pd–TiO₂ while of S. aureus was improved to 94% with Fe–TiO₂, showing in this case no significant difference when compared to Ag–TiO₂ and Pd–TiO₂. In contrast, inactivation of E. coli was not significantly increased when metal modified TiO₂ was used, ranging from 47% to 57%.
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