There are more jeans in the world than people. That sparked an idea in the mind of University of Sheffield chemist Tony Ryan. Why not use people’s penchant for wearing denim to help purify the air? With thoughts of reducing pollutants such as the nitrogen oxides and volatile organic compounds emitted by vehicles, power plants, residential heating, cooking and various consumer products, Ryan, in partnership with former fashion designer Helen Storey, came up with the concept of “Catalytic Clothing.” “Catalytic” apparel uses fabric impregnated with nano-sized particles of titanium dioxide to degrade air pollutants. “Nano” means small. So small that the combined surface area of the nanoparticles that are distributed through any fabric is immense. And that matters because the action takes place on the surface of the particles.
Titanium dioxide is a “photocatalyst,” meaning that it can make chemical reactions happen when exposed to the right wavelength of light, in this case ultraviolet. The light energy causes it to release electrons that then target water molecules in the air, breaking them apart to form extremely reactive hydroxyl radicals that then chop up organic compounds into simple molecules such as carbon dioxide and convert nitrogen oxides into water soluble nitric acid. This is not just theory, it is well established technology that already has commercial application, for example in “self-cleaning glass.”
A thin layer of titanium dioxide ends window cleaning worries, as long as the climate provides for sufficient sunshine and rain. The chemical can even be mixed into con Thanks to titanium dioxide, we may never have to confront yellow urinals again. Coating the ceramic with a layer of titanium dioxide, about one-50th the thickness of human hair, prevents stains from forming. The technology also has potential in operating rooms where bacteria on floor and wall tiles can be destroyed with fluorescent light, common in hospitals, furnishing enough of the right wavelengths.
Clearly, titanium dioxide photocatalysis is sound technology. But can wearing jeans treated with this chemical actually have an impact on air pollution? According to Professor Ryan if one-third of a million people in Sheffield wore such jeans, nitrogen oxide levels could be significantly reduced. And there is no need to buy special jeans. Titanium dioxide particles stick readily to the fabric, so the idea is to add a formulation of the chemical to the water when the jeans are being laundered. The nano particles will stick until the fabric degrades.
For more information please visit: www.sheffield.ac.uk
