Photocatalytic air purification
Photocatalytic air cleaning refers to a property of mostly building material surfaces, e.g. B. concrete, brick, plaster or paint, in the photocatalysts, for example nanoparticles made of titanium dioxide (TiO 2 ), were incorporated. When exposed to (sun) light , harmful gases (for example nitrogen oxides or volatile organic substances) are oxidized and thus removed from the air.
Mode of action using the example of titanium dioxide
The process is based on photocatalysis , in which titanium dioxide (TiO 2 ) serves as a catalyst . When irradiated with (mostly) UV light , radicals are formed on the surface of the titanium dioxide , which can decompose organic substances and oxidize gaseous substances (cf. photocatalytic self-cleaning ). In the case of the oxidation of nitrogen oxides, NO and NO 2 are converted into nitrate (NO 3 - ). This is readily soluble in water and is carried away from the surface with the rainwater. The catalyst itself is not consumed in the reaction and thus remains in the building material for the duration of its existence.
Applications
Photocatalytically air-cleaning surfaces have been used in Germany for some years to keep the air clean in cities, v. a. used on heavily used traffic arteries. Are used e.g. B. photocatalytically active paving stones, roof tiles / stones, paints and plasters. New processes make the principle usable for private households, for example by coating windows accordingly.
Web links
- Fraunhofer Photocatalysis Alliance
- Association of Applied Photocatalysis
- Photoactive building materials initiative
Individual evidence
- ↑ The window becomes "vacuum cleaner" - report in the specialist magazine "Glaswelt", issue 01/2019