W(VI)-TiO2 coated tiles with visible light induced antibacterial activity

CANDAL R.J.; PERULLINI M.; ORTEGA C.; ALBABE BILMES S.

Chicago, IL, EE.UU

Congreso; 10th Internacional Conference on TiO2 Photocatalysis: Fundamental and Aplications; 2005

Redox Technologies

W(VI) loaded TiO2 films show great potential for self-cleaning and antibacterial applications due to their photocatalytic activity under visible light. In this work we show that visible light induced antibacterial properties of W-TiO2 films deposited over tiles. Pure TiO2 and 2% mol/mol W-TiO2 sols were prepared by hydrolysis of titanium isopropoxide in water containing nitric acid and the required amount of ammonium metatungstate, followed by peptization at 80ºC for 12 hr. The sols were purified by successive centrifugation and re-suspension in pure water. Films were prepared by spraying the sols on clean commercial tiles (Fasimpat, Coop), followed by air-drying and firing at 400 ºC. To asses the light induced bactericidal activity of TiO2 and W-TiO2 films, liquid bacterial cultures of Escherichia coli were spray-dispersed over coated and non coated tiles (control). The tiles were then irradiated by UV (black light) (15 minutes treatment) or white light (45 minutes treatment). Cell viability was evaluated by contact spotting of samples onto solid culture medium. After 48 hours of incubation at 37 °C, classical methods of CFU counting were performed. Results show a significantly lower viability of E. coli strain over the coated tiles under both UV and white light exposure. Under black light illumination, viability of the cells over both, TiO2 and W-TiO2 coated tiles, was reduced to a 37% with respect to the control. Under white light illumination the viability was reduced to a 40% over TiO2 and to a 20% over W-TiO2 coated tiles. These results show that incorporation of tungsten enhance the bactericidal effect of TiO2 films under white light.  Poster