Photocatalysis is used in numerous fields, including air and water treatments and the industrial sector.
Photocatalysis, also called photocatalytic degradation is a very efficient clean-up process. A quick etymological analysis of the word will explain most of the concept: “Photo” which means light, and "Catalysis”. It is thus simply a chemical reaction accelerated by light.
In theory, photocatalysis is a simple oxidizing-reducing reaction which happens when light (UV rays) activates a semiconductor (TiO2).
In practice, the rays from the UV lamp, which is located in the middle of the purifier, are going to collide with the inner-layer of the multi-layer filter made from TiO2.
This results in a reaction where free radicals are created (also called “active oxygen”), with a strong clean-up power. Industrials often avoid using “free radicals”, as this expressions tends to frighten. Indeed, this is also the type of molecule that damages skin and that the much-talked-about antioxidants are supposed to fight. As it happens, it’s the strong reactivity of these molecules that allows them to fight atmospheric pollution so efficiently, and all of that happens within our appliance.
Where there is chemical pollution, free radicals are going to react with the chemical components present in the atmosphere and degrade them. Where there is no pollution, they will stay stable. Their high reactivity to nearby molecules gives them a very short life.
Our photocatalysis technology produces no ozone (or in infinitesimal amounts). For that matter, photocatalysis actually destroys the ozone present in the air and prevents new production by breaking down its precursors ( oxides and other gas).
What kind of pollution does photocatalysis target ?
Photocatalysis is a clean-up technology (and not filtering) that is extremely efficient against chemical pollution, notably against gaz pollutants, otherwise known as VOC (Volatile organic compounds). VOC can occur naturally but are more often anthropogenic. These are gases that result from industrial activities ( organic solvents, cleansing agents, synthesising agent, etc). Sprays, maintenance products and cosmetics, paints and solvents are the biggest culprits.
Amongst the most notable VOCs that are eliminated through photocatalysis are nitrogen oxide, CO2 and CO, formaldehyde, ethanol, butane, toluene, benzene and acetone.
Numerous scientific studies1,2 have been published these last few years that suggest significant efficiency of photocatalysis against bacteria and viruses, notably the flu virus.
- Nakano R, Ishiguro H, Yao Y, Kajioka J, Fujishima A, Sunada K, Minoshima M, Hashimoto K, Kubota Y. (2012, August). Photocatalytic inactivation of influenza virus by titanium dioxide thin film. Source.
- Hajkova et al. (2007). Photocatalytic Effect of TiO2 Films on Viruses and Bacteria.