New Wall Paint Cleans Itself, Purifies Air

WEDNESDAY, MARCH 27, 2024


A research team from Vienna University of Technology (TU Wien) and the Università Politecnica delle Marche in Italy have developed special titanium oxide nanoparticles that can be added to commercially available wall paint to make it self-cleaning.

Additionally, the paint offers several benefits for sustainability. The new paint was created using raw material waste and dried fallen leaves, and it also helps to clean the air around it as it cleans itself overtime.

The work was recently published in the journal ACS Catalysis.

About the Study

Typically, white wall paint does not stay white, as various substances from the air accumulate on its surface over time. While this makes the air cleaner after a while, the color change requires a repaint.

A wide variety of pollutants occur in indoor air, TU Wien explains, from residues of cleaning agents and hygiene products to molecules that are produced during cooking or that are emitted by materials such as leather.

In some cases, this can lead to health issues, which is then referred to as “sick building syndrome.”

“For years, people have been trying to use customized wall paints to clean the air,” said professor Günther Rupprechter from the Institute of Materials Chemistry at TU Wien. “Titanium oxide nanoparticles are particularly interesting in this context. They can bind and break down a wide range of pollutants.”

According to the university, the nanoparticles are photocatalytically active and can use sunlight not only to bind substances from the air, but also to decompose them afterwards. The wall also then makes the air cleaner and cleans itself at the same time.

However, adding ordinary titanium oxide nanoparticles to the paint affects the durability of the paint. The team says that, just as pollutants are degraded by the nanoparticles, they can also make the paint itself unstable and create cracks.

In the worst case, volatile organic compounds can be released, which in turn can be harmful to health.

The researchers explain that these nanoparticles can clean themselves if they are irradiated with UV light, since TiO2 is a photocatalyst that enables chemical reactions when exposed to suitable light.

The UV radiation consequently creates free charge carriers in the particles, which induce decomposition of the trapped pollutants from air into small parts and their release. As a result, the pollutants are rendered harmless, but do not remain permanently attached to the wall paint and the color reportedly remains stable in the long term.

However, in practice, this method is tedious and impractical, since the paint would constantly need to be repeatedly irradiated with intense UV light in order to drive the self-cleaning process.

“Our goal was therefore to modify these particles in such a way that the photocatalytic effect can also be induced by ordinary sunlight,” explained Rupprechter.

The scientists reportedly achieved this by adding certain additional atoms to the TiO2 nanoparticles, such as phosphorus, nitrogen and carbon. The light frequencies that can be harvested by the particles then change and, instead of just UV light, photocatalysis is then also triggered by ordinary visible light.

“We have now investigated this phenomenon in great detail using a variety of different surface and nanoparticle analysis methods,” said Qaisar Maqbool, the first author of the study. “In this way, we were able to show exactly how these particles behave, before and after they were added to the wall paint.”

The research team reportedly mixed the modified titanium oxide nanoparticles with commercially available wall paint and then rinsed a painted surface with a solution containing pollutants.

According to the university, 96% of the pollutants could be subsequently degraded by natural sunlight. The color itself does not change because the pollutants are not only bound, but also broken down with the help of sunlight.

Additionally, the paint reportedly combines several sustainable advantages, including removing pollutants from the air and lasting longer than other paints. It was created while avoiding expensive raw materials.

“In catalysis, for example, precious metals such as platinum or gold are used. In our case, however, elements that are readily available from everywhere are sufficient. To obtain phosphorus, nitrogen and carbon, we have used dried fallen leaves from olive trees, and the titanium for the titanium oxide nanoparticles was obtained from metal waste, which is normally simply thrown away,” said Rupprechter.

TU Wien says that further experiments are being carried out, and the team intends to commercialize the wall paint.

   

Tagged categories: Air pollution control; Air quality; Asia Pacific; Coating Materials; Coating Materials - Commercial; Coatings Technology; Colleges and Universities; EMEA (Europe, Middle East and Africa); Green coatings; Hazardous air pollutants; Health & Safety; Indoor air quality; Interior Wall Coatings; Latin America; North America; Paint; Photocatalytic coatings; Program/Project Management; Research and development; Self-cleaning coatings; Sustainability; Z-Continents

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