Photochemistry of atmospheric dust: ozone decomposition on illuminated titanium dioxide.
Environ Sci Technol
; 43(19): 7437-42, 2009 Oct 01.
Article
en En
| MEDLINE
| ID: mdl-19848158
ABSTRACT
The ozone decomposition onto mineral surfaces prepared with traces of solid TiO2 in a matrix of SiO2 in order to mimic mineral dust particles has been investigated using a coated-wall flow-tube system at room temperature and atmospheric pressure. The ozone uptake coefficients were measured both under dark conditions and irradiation using near UV-light. While uptake in the dark was negligible, a large photoenhanced ozone uptake was observed. For TiO2/SiO2 mixtures under irradiation, the uptake coefficients increased with increasing TiO2 mass fraction (from 1 to 3 wt %), and the corresponding uptake coefficient based on the geometric surfaces ranged from 3 x 10(-6) to 3 x 10(-5). The uptake kinetics was also observed to increase with decreasing ozone concentration between 290 and 50 ppbv. Relative humidity influenced the ozone uptake on the film, and a reduced ozone loss was observed for relative humidity above 30%. The experimental results suggest that under atmospherically relevant conditions the photochemistry of dust can represent an important sink of ozone inside the dust plume.
Search on Google
Banco de datos:
MEDLINE
Asunto principal:
Ozono
/
Atmósfera
/
Titanio
/
Contaminantes Atmosféricos
/
Polvo
Idioma:
En
Año:
2009
Tipo del documento:
Article