Photochemistry of atmospheric dust: ozone decomposition on illuminated titanium dioxide

Environ Sci Technol. 2009 Oct 1;43(19):7437-42. doi: 10.1021/es901569d.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Air Pollutants / chemistry*
  • Atmosphere / chemistry*
  • Dust / analysis*
  • Ozone / chemistry*
  • Photochemistry
  • Titanium / chemistry*

Substances

  • Air Pollutants
  • Dust
  • titanium dioxide
  • Ozone
  • Titanium