Self-cleaning walls…an innovative scientific solution for developing paints
Self-cleaning walls…an innovative scientific solution for developing paints
Modern trends in interior design have tended, in one way or another, to bright colors in wall paint, such as white and its derivatives. However, the problem with these colors is that they do not retain their beauty for a long time. Because of the ease with which they become dirty with many air pollutants that accumulate on their surfaces, and after a period of time these pollutants contribute to changing the basic color of the walls. Which makes us need to repaint it again.
To solve the previous problem, a team of researchers from the Technical University of Vienna succeeded in cooperating with researchers from the Technical University of Marche (Italy) to develop nanoparticles oftitanium oxide, which can be added to traditional, commercially available wall paint. To give these coatings the ability to self-clean themselves.
Innovative new titanium oxide nanoparticles are stimulated by visible light; Therefore, only natural lighting (sunlight) can be relied upon. To photo-stimulate these particles, they attract air pollutant particles, then break them down and release them again. Which means that paints with these particles added can contribute to purifying the surrounding air, in addition to cleaning themselves.
What’s interesting is that the research team used waste – such as scrap metal and fallen tree leaves – as raw materials for this innovative type of self-cleaning paint. In the following lines, we will discuss with you – in detail – the method of making this new type of paint, which can contribute to achieving a number of Sustainable Development Goals (SDGs).
Modified titanium oxide nanoparticles
Types of indoor air pollutants vary from residues of cleaning materials and gases produced during cooking food, to particles resulting from the use of clothing and shoes. All of the above affects indoor air quality, leading – in the long run – to some health problems, such as “sick building syndrome.”
Concerning this, Professor Gunther Ruprechter from the Institute of Materials Chemistry at the Technical University of Vienna said: “For years there have been many attempts to use custom wall paints to clean indoor air, and here titanium oxide nanoparticles appeared in an interesting way; “Its ability to attract and break down a wide range of air pollutants, but there were some significant obstacles to relying on it in a practical way.”
The problem with adding titanium oxide nanoparticles to paint is that they greatly affect its durability, as these particles break down air pollutant particles, but the products of the breakdown process remain attached to the wall. It negatively affects the stability of the paint layer itself, and cracks begin to appear on it. Also, in some cases, a group of volatile organic compounds (VOCs) are released into the air, which are very harmful to health, and after a certain period of time the color of the paint layer changes. Which requires re-application.
Self-cleaning with light
Titanium oxide nanoparticles are characterized by their ability to clean themselves if they are exposed to ultraviolet light. Titanium oxide is known as a photocatalyst, meaning that it is a substance that makes chemical reactions possible when exposed to appropriate light.
So, ultraviolet radiation can be exploited, for example, to generate additional negative charges (electrons) on nanoparticles; Which leads to the decomposition of pollutants captured from the air into small parts, which are then released. In this way, the pollutants become harmless, and they do not remain permanently attached to the wall paint, so its color remains stable in the long term.
The problem with the previous idea is that we will constantly need to stimulate the wall paint – repeatedly – using intense ultraviolet light; To stimulate the self-cleaning process. This is difficult to apply in reality. Therefore, the research team worked to modify these nanoparticles, so that they could be photocatalyzed by ordinary sunlight.
The idea is to add additional atoms to the titanium oxide nanoparticles, such as phosphorus, nitrogen, and carbon atoms, with the aim of changing the frequencies of light that can be absorbed by these modified nanoparticles, instead of just ultraviolet light, so that it becomes possible to photoexcite the titanium oxide nanoparticles with ordinary visible light.
96% pollutant removal
“We have studied the photocatalysis phenomenon in great detail using a variety of different surface and nanoparticle analysis methods, which has enabled us to precisely demonstrate the behavior of titanium oxide nanoparticles before and after they are added to wall paint,” said Qaiser Maqbool, first author of the study.
To ensure the effectiveness of the modified nanoparticles, the research team mixed titanium oxide particles with regular commercially available wall paint, then rinsed the painted surface with a solution containing a group of pollutants. The result was that 96% of the pollutants were broken down by stimulating the particles with natural sunlight, and this without any effect on the color of the paint layer.
In order to achieve the desired success of these innovative coatings on a commercial level, it is important to avoid expensive raw materials, which is what the team was able to achieve; Phosphorus, nitrogen, and carbon are all cheap and available materials, and can even be obtained from waste such as fallen tree leaves, while titanium oxide can be obtained from metal waste (scrap).
This new type of wall paint combines many advantages at the same time; It removes pollutants from the air, lasts longer than other paints, and is more resource-efficient during its production process, as waste and recycled materials can be used as raw materials. All of the above undoubtedly contributes to achieving a number of goals ofsustainable development; The most notable are Goal 9 (industry, innovation and infrastructure), Goal 11 (sustainable cities and communities), and Goal 12 (responsible consumption and production).
