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News: Delhi government and IIT Madras began a six-month study on “smog-eating” photocatalytic coatings to test reduction of NO₂ and volatile organic compounds (VOC) pollutants.
About Smog-Eating Photocatalytic Coatings
- It is a coating using titanium dioxide that neutralizes harmful gases like nitrogen dioxide (NO2) and volatile organic compounds (VOCs).
- Mechanism
- Photocatalytic activity uses light energy to break down harmful substances and organic waste into less toxic or harmless matter.
- When exposed to sunlight, titanium dioxide acts as a catalyst and generates surface electrons.
- These electrons react with pollutants such as nitrogen dioxide and volatile organic compounds and dismantle them.
- This process helps in making air and water cleaner.
- Technology used: Titanium dioxide is used as it is low-cost, chemically stable and compatible with construction materials.
- Targeted pollutants: It targets nitrogen dioxide and volatile organic compounds and prevents secondary particulate matter and ground-level ozone formation.
- Applications: It is applied on roads, pavements, buildings, and tiles, where it works as a passive air-cleaning system.
- Limitation: Its efficiency reduces due to low sunlight, dust accumulation, and wind conditions, and it may cause nitrate runoff leading to eutrophication in water bodies like Yamuna.
