Inactivation of Bacterial Spores and Vegetative Bacterial Cells by Interaction with ZnO-Fe₂O₃ Nanoparticles and UV Radiation

Abstract

ZnO-Fe2O3 nanoparticles (ZnO-Fe NPs) were synthesized and characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and dynamic light scattering (DLS). The generation of chemical reactive hydroxyl radicals (•OH) was measured spectrophotometrically (UV-Vis) by monitoring of p-nitrosodimethylaniline (pNDA) bleaching. Inactivation of E. coli and B. subtilis spores in the presence of different concentrations of ZnO-Fe NPs, under UV365nm or visible radiation, was evaluated. We observed the best results under visible light, of which inactivation of E. coli of about 90% was accomplished in 30 minutes, while B. subtilis inactivation close to 90% was achieved in 120 minutes. These results indicate that the prepared photocatalytic systems are promising for improving water quality by reducing the viability of water-borne microorganisms, including bacterial spores.

Keywords

• Drinking water
• nanoparticles
• photocatalysis
• hydroxyl radicals
• zinc oxide
• iron oxide
• Bacterial inactivation
• Bacterial spore inactivation