Walls clean and purify the air: development of a new paint additive – Science –

A research team from Vienna University of Technology (TU) and Italy's Politecnica delle Marche University reported in the specialist journal ACS Catalyze the development of an additive for wall paints that uses sunlight to activate self-cleaning of contaminated deposits and discoloration and can also clean the air. In addition, producing it using readily available recycled materials is “relatively simple,” Gunther Ruprechter told the APA.

The white powder, which can be added to regular water-based wall paints, works thanks to special titanium oxide nanoparticles. “Titanium oxide has long been used as a pigment in sunscreens and white paints,” says Ruprichter of the Institute of Materials Chemistry at the Vienna University of Technology. “People already knew about the self-cleaning effects and had tried a lot in this area.” These effects result from the photocatalytic properties of the material: that is, it can enhance chemical reactions under the influence of light.

“Natural titanium oxide needs ultraviolet light to do this,” Robichter continued. Although this is present in sunlight, under normal circumstances only a small portion of it can be used by particles. By adding certain additional atoms, such as phosphorus, nitrogen and carbon, the team was able to change the frequencies of light that the particles can absorb. Instead of using only UV light, photocatalysis is also stimulated by natural sunlight.

Energy from sunlight stimulates the electrons in the titanium oxide and free charge carriers are created: “These then trigger chemical reactions and decompose the contaminants,” says Ruprechter. However, free shipping companies tend to repackage. This may become a problem if it is reassembled before the contaminant decomposes. “Through our measurements we showed that adding other atoms increases the time for the charge carriers to jump together again sevenfold,” the researcher explained.

“We studied this phenomenon in great detail using a variety of different surface and nanoparticle analysis methods,” Qaiser Maqbool, first author of the study, was quoted as saying in a press release. “This allowed us to show exactly how these molecules behave before and after they are added to the wall paint.” As part of the experiments, the research team mixed the particles with commercially available wall paint and washed the painted surface with a solution containing the pollutants. Sunlight then removed 96% of the pollutants from the surface. “The more light that ends up hitting it, and the larger the area, the better for the interaction,” Ruperchter added. The molecules thus develop their full effect on external surfaces.

“Usually, these additives attack not only contaminants, but also the paint itself. If the polymer found in many paints dissolves, it can be harmful to health,” said Robichter. However, through pre- and post-tests, the research team showed that the color composition did not change during the tests.

In the production of the color additive, inexpensive raw materials were also used: phosphorus, nitrogen and carbon were obtained from dried leaves of olive trees, and titanium for titanium oxide particles was obtained from mineral waste. Ruprechter says that commercialization of this innovation is currently underway. It is also planned to conduct more experiments to produce the additive in other ways and examine the effectiveness of the substance in decomposing gaseous pollutants in the air.