Photocatalysis, what it is and how it works

Photocatalysis, what it is and how it works

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How does thephotocatalysis process, what it is used for and the role of titanium dioxide to purify the air.

Thephotocatalytic processit is used to purify the air by reducing the concentrations of polluting particles suspended in the atmosphere through the action oftitanium dioxide and by the action of the sun's rays. In particular, thephotocatalysisgoes to neutralize thenitric oxide.

Thephotocatalytic processis exploited in thegreen buildingfor the construction of building elements with anti-polluting properties. In construction, external cladding elements are spreading (plasters, roof tiles, facade panels ...) described under the name of "eat-smog " precisely because they have the ability to hold backfine dustnitric oxideand other pollutants.

How the photocatalysis process works

Therephotocatalysisit is a set of reactionsphotochemicalsmade possible by a light-sensitive catalyst. Classic photocatalysts are given by metallic compounds such as zinc oxide, cerium (IV) oxide, zinc sulphide, cadmium sulphide, tin dioxide, zirconium oxide ... In green building, the most used photocatalyst is thetitanium dioxide(or titanium dioxide TiO2) thanks to which authentic coatings are madesmog-eating.

The titanium dioxide, in the presence of sunlight it is able to attract and retain water molecules suspended in the air in the form of moisture and together with the water it also captures fine dust (PM10), nitrogen oxide and other suspended polluting particles, up tomineralize.

If, on a chemical level, this mechanism sounds strange to you, know that the trigger of the photocatalysisare solar rays intended as ultraviolet rays with an ideal wavelength to modify the structure of the molecular orbitals of TiO2 and make the whole reaction possible.

In green building, thetitanium dioxideit is combined with concrete and, in addition to eliminating a small part of the smog present in the atmosphere, it manages to guarantee always clean facades by eliminating all the polluting organic components. The most famous application of photocatalytic coatings in Italy took place in the context of Expo 2015 with the Palazzo Italia in Milan.

Not just facades and external cladding. There is no shortage of building producers who offer photocatalytic tiles for interiors. in this context, the photocatalytic process is exploited to ensure clean floors and able to constantly break down bacterial loads and degrade any harmful particle. Also in this case the protagonist is titanium dioxide but unlike the external facades (where the rain regenerates the photocatalytic activity of the coating, eliminating any saturation), the floors will need to perform the classic maintenance with water.

Other applications of the photocatalysis process

The applications of thephotocatalysisdo not concern only the building sector photocatalysisis exploited in the treatments ofair and water purification. In the medical field, with thephotocatalysissome cancer cells are counteracted and in the health sector and in research laboratories thephotocatalysisas a means of disinfection.

In the industrial field, thephotocatalysisit is used in the production of glass and other materialsself-cleaning, in practice these materials clean themselves by eliminating dirt simply by coming into contact with light. Again for glass and mirrors, thephotocatalysis processit is used for its "anti-fog" action, offering a surface completely immune to water. To give you an example, imagine the glass in the shower enclosure coated with materials with photocatalytic properties ... in this case the steam produced by boiling water would not cloud the glass.

Still, leveraging thephotocatalysis processit is possible to produce hydrogen forphotocatalytic splitting of water.In this case, NaTaO is used3 and nickel oxide as catalysts and UV light. The hydrogen produced with thephotocatalysis processit can be used as an energy source to power cars with fuel cells or for the storage of renewable energy.

Video: Photocatalysis (August 2022).