Air pollution and its high concentration in cities is one of the problems facing society today, due to its harmful effects on the environment, but also on human health. One of the causes of this pollution is the increase in nitrogen oxide emissions, mainly due to the use of fossil fuels.
While the emissions of these gases are being reduced, photocatalysis is proving to be a tool for decontaminating air in cities: materials called semiconductors are created which, when coming into contact with the pollutant, under the effect of ultraviolet light, cause it to degrade, thus reducing its concentration in the air.
Two research groups of the University of Cordoba, belonging to the Chemical Institute for Energy and the Environment (IQUEMA),and the Department of Inorganic Chemistry and Chemical Engineering,have been working to produce these materials. The team,formed by the BioPrEn and Inorganic Chemistry groups, has obtained biodegradable materials to fix nanoparticles with photocatalytic activity (in this case, titanium dioxide), augmentingthe power and, therefore,the decontaminating effect.
The advances made by this work consist of "first, the creation of a biodegradable medium based on nanocellulose, obtained from agricultural waste; and, second, the development of a surface modification process of these nanoparticles, which results on their greater dispersion and immobilization,and, therefore, enhanced photocatalytic activity", explains one of the authors of the article, researcher Eduardo Espinosa.
The progress is twofold: it is possible to create a sustainable material by recovering a form of agricultural waste(thus contributing to the Circular Economy) and the process of fixing photocatalytic nanoparticles to this biodegradable medium is simplified. The benefit is, in fact, exponential, since the result is greater air decontamination due to the porosity and the three-dimensional nature of the material, which means that more photocatalytic particles are exposed to ultraviolet light compared to an opaque material or one in which only one surface is exposed to light.
What is it like? Where is it used?
This material is light and has a low density, similar to construction insulation or corn puffs. When used for decontamination purposes, it can serve as a porous filter for gas streams, allowing them to pass through and be exposed to ultraviolet light, resulting in decontamination. As Eduardo Espinosa explains, industrial gas emissions can pass through this filter and come out almost completely free of nitrogen oxides.
The next step in this research would be to modify the photocatalytic particles to make them more sensitive to light from the visible spectrum, eliminating the need for ultraviolet light sources. This modification would enable the activation of photocatalytic power by sunlight alone, allowing this technology to be applied to textiles and other materials, thereby reducing gas concentration through exposure to sunlight only.
References: Carrasco, Sergio & Espinosa Víctor, Eduardo & González, Zoilo & Cruz-Yusta, Manuel & Sánchez, Luis & Rodríguez, Alejandro (2023). Simple Route to Prepare Composite Nanocellulose Aerogels: A Case of Photocatalytic De-NO x Materials Application. ACS Sustainable Chemistry &Engineering. https://doi.org/10.1021/acssuschemeng.2c06170
Source: University of Cordoba