Photocatalytic NOx Removal
NOx + O2 + H2O → HNO3
Overview
TiO₂ photocatalyst on building surfaces oxidizes nitrogen oxides (NOx) from vehicle exhaust to nitric acid (HNO₃), which is then washed away by rain. Photocatalytic concrete and pavement coatings can reduce local NOx levels by 25–45%. This passive pollution remediation works continuously in sunlight.
Participants
| Role | Substance | Coefficient | State |
|---|---|---|---|
| Reactant | Water H₂O | 1 | (l) |
| Product | Nitric Acid HNO₃ | 1 | (aq) |
Everyday Example
Some cities use photocatalytic concrete in roads and buildings that actively clean the air of vehicle exhaust pollution.
Industrial Importance
Photocatalytic construction materials represent a growing market for air quality improvement in urban environments.
Properties
- Type
- Photochemical
- Reversible
- No
- Energy
- Exothermic
- ΔH
- -206.0 kJ/mol
- Catalyst
- TiO₂ (titanium dioxide)
Related Reactions
Chlorophyll Fluorescence
Cis-Trans Isomerization of Retinal
Dye-Sensitized Solar Cell (Grätzel Cell)
Firefly Bioluminescence (Luciferin Oxidation)
Luminol Chemiluminescence
Ozone Decomposition by UV
Ozone Formation by UV Light
Photocatalytic Water Splitting (TiO₂)
Photochemical Cycloaddition ([2+2])
Photochemical Smog Formation (NO₂ Photolysis)
Frequently Asked Questions
What is the equation for Photocatalytic NOx Removal?
The balanced equation is: NOₓ + O₂ + H₂O → HNO₃.
What type of reaction is Photocatalytic NOx Removal?
Photocatalytic NOx Removal is a photochemical reaction.
Is Photocatalytic NOx Removal exothermic or endothermic?
Photocatalytic NOx Removal is exothermic (releases energy). The enthalpy change (ΔH) is -206.0 kJ/mol.
What conditions are needed for Photocatalytic NOx Removal?
This reaction requires a catalyst (TiO₂ (titanium dioxide)).