TiO2 mediated photocatalytic inactivation of airborne bacteria

Abstract

Microbial pollutants such as bacteria are one of the significant sources of indoor air pollution. The first phase of this research aims to examine inactivation efficiencies of eight bacterial species using a batch disinfection system with TiO2 assisted photocatalytic reactions coupled with a fluorescent light or UV-A lamp. The maximum inactivation of most bacteria was achieved at an optimum TiO2 loading of 511-1666 mg/m2. Gram-negative bacterium E. coli K-12 was most effectively inactivated (0.2442 min-1), while Gram-positive Bacillus subtilis exhibited the most resistant response to the photocatalytic treatment (0.0057 min-1). In the second phase, a continuous reaction system was developed to examine effects of light intensity (0.5 to 3.4 mW/cm2), TiO2 loadings (960 and 1516 mg/m2) and relative humidity (RH) (51 B1 0.61 to 85 B1 4.7%) on inactivation efficiencies of aerosolized E. coli K-12. Results showed an increase in bacterial inactivation with increasing UV-A intensity, TiO2 loading and RH.