Photocatalysis An inevitable by-product of industrialization and modernization has been and is, environmental pollution. This industry is often regarded as one of the major contributors to this. Both the building process and the use of the property significantly contribute to the contamination of resources such as water and air. One of the most important challenges facing the construction industry in the 21st century is developing building materials that are sustainable, functional, and environmentally friendly.
This has led to the development of photocatalyst materials that are compounds that, by absorbing light, facilitate a chemical reaction and regenerate in the process. Research on the use of photocatalytic acting synergistically with construction raw materials is in progress. According to the latest tests, thanks to the chemical reactions of photo-catalytic elements with atmospheric pollutants, a building considered 100% photo-catalytic could eliminate almost 89% of the NOx particles from its environment. And the basic cost of these materials is only 5/10% higher than conventional ones.
History of photocatalysis in construction
A new panorama has been opened for the building material with the discovery of the photocatalytic activity of TiO2 in 1972. Research has shown that these materials with special binders are capable of absorbing NOx ions on the surface and transforming them into ions. not harmful in the form of salts (nitrates), which, although they remain on the walls, can be removed by rain or with a facade cleaning. A similar process occurs with gases of the SOx type and the production of ozone, which causes a series of respiratory diseases, can also be counteracted. In recent years rapid progress has been made to develop materials based on photo-catalytic elements.
The initial drive for the production of photocatalytic material was to achieve antibacterial and self-cleaning surfaces. Since the first trials by the Japanese in the 1990s, the use of photocatalytic material has come a long way. The most famous application is the one made in the church "Dives de Misericordia" in Rome. Since one of the requirements was the maintenance of color, a series of tests were carried out on concrete mixes and the church was inaugurated in 2002.
Two other important pioneer buildings, constructed from photo-catalytic materials, are a school in Mortara, Italy, which was completed in 1999 and the Cité de la Musique in Chambéry, France, which opened in 2000. In all cases maintenance The color was achieved without problems, but the most significant thing was that the level of air pollution in the areas surrounding these constructions was considerably improved.
Photocatalysis in Spain The European Environment Agency has pointed out that Spain is the EU country with the highest levels of polluting gas emissions (and Minister Soria on behalf of the government has asked that they let us pollute more) so the problem is pressing.
Faced with such a challenge as that of decontaminating the air, the construction sector is willing to do something to help reduce the effects of emissions, applying photo-catalytic materials capable of chemically reacting with the most dangerous gases, turning them into diverse substances that are much less harmful. With photo-catalysts it is possible to produce a wide range of construction materials such as: paving stones, pavements, ceramics, waterproofing covers, cement, etc.
These differ from the traditional ones in that after the application of a chemical process, their properties are transformed and therefore they are capable of reacting under the effect of light and causing oxidation of the most common polluting gases in the atmosphere, such as SOx, NOx and VOCs. At present, although the enormous possibilities offered by these materials are not widely exploited, there are already specific applications of them in some new buildings.
There is no doubt of the enormous potential that this type of materials could represent at the level of large cities, since it would unleash, as predicted by the AIF (Asoc. Ibérica de Fotocatalysis), a positive and medium-term revolution in the environmental field.
The AIF proposes a truly innovative concept called “photo-catalytic islands”, which consists of choosing key urban areas where to use these materials during the building maintenance and conservation processes (improvement of facades, new roofs, enclosures, etc.) and in new construction.
As an example, they propose that if they were applied in the Ensanche of the city of Barcelona, which is the point with the highest concentration of NOx pollution in the entire city, a very significant reduction in harmful gases could be achieved, which would change the level of toxicity of the air dramatically.
The plan (for now merely "virtual") is to turn a certain block in the Ensanche into an "imaginary photo-catalytic island" with "green" pavers that would cover 3,600 m2 of interior patios, 9,000 m2 would be waterproofed with special asphalt sheets, 25 vertical meters and 427 linear meters of tiles would be placed on various facades and photo-catalytic paint would be applied in the underground car parks in more than 12,000 m2.
Laboratory tests predict that this "photo-catalytic island" would be capable of eliminating up to 300 kg of NOx per year, that is, "cleaning" 8 billion m3 of air, which would be equivalent to taking 80,000 vehicles off the road, so that more 1,100,000 Barcelonans could breathe air free of polluting gases.