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Photoactive roadways: Determination of CO, NO and VOC uptake coefficients and photolabile side product yields on TiO2 treated asphalt and concrete
- Source :
- Atmospheric Environment. 139:37-45
- Publication Year :
- 2016
- Publisher :
- Elsevier BV, 2016.
-
Abstract
- This work reports uptake coefficients and by-product yields of ozone precursors onto two photocatalytic paving materials (asphalt and concrete) treated with a commercial TiO2 surface application product. The experimental approach used a continuously stirred tank reactor (CSTR) and allowed for testing large samples with the same surface morphology encountered with real urban surfaces. The measured uptake coefficient (γgeo) and surface resistances are useful for parametrizing dry deposition velocities in air quality model evaluation of the impact of photoactive surfaces on urban air chemistry. At 46% relative humidity, the surface resistance to NO uptake was ∼1 s cm−1 for concrete and ∼2 s cm−1 for a freshly coated older roadway asphalt sample. HONO and NO2 were detected as side products from NO uptake to asphalt, with NO2 molar yields on the order of 20% and HONO molar yields ranging between 14 and 33%. For concrete samples, the NO2 molar yields increased with the increase of water vapor, ranging from 1% to 35% and HONO was not detected as a by-product. Uptake of monoaromatic VOCs to the asphalt sample set displayed a dependence on the compound vapor pressure, and was influenced by competitive adsorption from less volatile VOCs. Formaldehyde and acetaldehyde were detected as byproducts, with molar yields ranging from 5 to 32%.
- Subjects :
- Atmospheric Science
Materials science
Ozone
010504 meteorology & atmospheric sciences
Vapor pressure
Formaldehyde
Continuous stirred-tank reactor
010501 environmental sciences
01 natural sciences
chemistry.chemical_compound
Chemical engineering
chemistry
Asphalt
Photocatalysis
Organic chemistry
Relative humidity
Water vapor
0105 earth and related environmental sciences
General Environmental Science
Subjects
Details
- ISSN :
- 13522310
- Volume :
- 139
- Database :
- OpenAIRE
- Journal :
- Atmospheric Environment
- Accession number :
- edsair.doi...........cba2d1919b016a9a5f94df36f6d6f743