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Titanium Dioxide Promotes New Particle Formation: A Smog Chamber Study
Hong Zhang1,2, Biwu Chu2,3,4, Jun Liu2
1Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing100083, China.
Environmental Science & Technology
|January 2, 2023
Summary
Titanium dioxide (TiO2) coatings significantly enhance new particle formation (NPF) by promoting sulfuric acid production. This effect, crucial for understanding urban air pollution, persists even with surface sulfate buildup.
Area of Science:
- Atmospheric Chemistry
- Environmental Science
- Materials Science
Background:
- Titanium dioxide (TiO2) is prevalent in building coatings.
- TiO2 is known to promote sulfur dioxide (SO2) oxidation and sulfate formation.
- The role of TiO2 in gaseous sulfuric acid (H2SO4) production and new particle formation (NPF) is not well understood.
Purpose of the Study:
- To investigate the impact of TiO2 on NPF in a controlled environment.
- To quantify the influence of TiO2 on particle formation and growth rates.
- To elucidate the mechanisms by which TiO2 affects H2SO4 production and NPF.
Main Methods:
- Experiments were conducted in a 1 m³ quartz smog chamber.
- NPF was studied in the presence of TiO2 under varying conditions.
- Particle formation and growth rates were measured and quantified.
Main Results:
- TiO2 significantly promotes NPF, increasing particle formation and growth rates.
- The promotion is attributed to enhanced gaseous H2SO4 production.
- The effect diminished with surface sulfate formation but showed partial recovery after washing.
- NPF promotion by TiO2 was observed across different relative humidity (RH) levels, peaking at 20% RH.
Conclusions:
- TiO2 coatings play a significant role in atmospheric H2SO4 production and NPF.
- The findings highlight the environmental impact of TiO2 on urban particle pollution.
- Understanding these processes is crucial for air quality management.
