Nanoparticles to remove harmful gases in closed spaces

Scientists have developed nanoparticles that absorb polluting gases in closed spaces. When receiving light, the nanoparticles degrade gases harmful to health that may have entered from the outside, such as those derived from combustion in vehicles. The results of the experiments show that these nanoparticles efficiently clean the air and could be used, for example, in the paint that covers the walls inside buildings. Thus, such closed spaces would tend to have cleaner air.

This technological advance is the work of an international research team from the Universities of Cádiz (Spain), Aveiro (Portugal) and Bratislava (Slovakia).

The work of scientists from the Nanomaterials Structures and Chemistry group at the University of Cádiz focused on establishing the structure of nanoparticles and studying their ability to reduce the adverse health effects of three harmful gases: benzene, isopropanol and nitrogen oxides. “The resulting material is in the form of a powder and works by a process similar to photosynthesis. In the same way that a plant traps CO2 to generate nutrients, nanoparticles are activated by light, absorb harmful gases and transform them into harmless ones ”, explains Luc Lajaunie, a researcher at the University of Cádiz, to the Discover Foundation.

The team presents the details of its technical advance in the academic journal Chemical Engineering Journal, under the title “Graphene-TiO2 hybrids for photocatalytic aided removal of VOCs and nitrogen oxides from outdoor environment”.

The researchers studied the nanoparticles to better understand their chemical qualities through a unique microscope in Spain, which can perform several types of analysis at the same time. With it, in addition to taking very detailed images of the particles, the experts verified how they physically reacted with the interaction of light and harmful gases, or how long it took to reduce their effects, among other issues.

These particles are made up of graphene sheets and titanium oxide spheres, so tiny that they look the same as dust. The first is a very thin carbon sheet characterized by its lightness and resistance and which is currently used to develop components such as cables or screens in the technology industry. On the other hand, titanium oxide is a chemical compound present in cosmetics, enamels, paints or plastics, among other materials of daily use. In addition, it has a quality that ‘filters’ harmful elements in the water and the air. “By studying the chemical qualities of each material, we found that graphene enhances the ‘cleaning’ properties of titanium oxide,” says Luc Lajaunie.

Titanium oxide nanoparticles. (Photo: Universities of Cádiz, Aveiro and Bratislava / Discover Foundation)

To make the nanoparticles, the experts used concentrations of graphene of 5 nanometers, the same size as the tip of a hair, and 20 nanometers of titanium oxide, equivalent to what a speck of dust measures.

Thus, the experts tested the action of the nanoparticles in a simulated environment. First they were placed in a reactor, a cylindrical stainless steel machine with a sealed glass window whose function was to allow in an artificial light, which reproduced the solar. In addition, the scientists placed LED lights inside to make the environment similar to that of an interior room. Then, they released the harmful gases that vehicle combustion gives off: nitrogen oxides, isopropanol and benzene. In this way, the experts analyzed and verified how long it took for these to be reduced and with what concentration of nanoparticles gave the best degradation performance.

Currently, this international research team focuses its work on two issues. On the one hand, the combination of these graphene and titanium oxide nanoparticles with other materials to make their application easier. On the other hand, scientists analyze how to use sunlight to generate clean energy and alternative materials to produce green hydrogen, that is, hydrogen that is produced from renewable energies and that when burned only produces water vapor instead of the common greenhouse gases. (Source: Discover Foundation)

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