Scientists developed a method that allows removal of antibiotic residue from waste water

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Organic aerogels prepared from oil shale phenolic compounds. Photo by Mihkel Koel

In February  the article “Metal-doped organic aerogels for photocatalytic degradation of trimethoprim” written by the researchers of two research groups (nanoporous materials and environmental technology research groups) of Tallinn University of Technology was published in the high-impact peer-reviewed professional journal Chemical Engineering Journal.

The head of the nanoporous materials research group, Lead Research Scientist Mihkel Koel, has, as a chemist, focused his research in particular on the implementation of the principles of waste-free chemistry, i.e. green chemistry. This article is also about development of new and effective methods for improving our living environment.
Mihkel Koel said, “In modern materials science, the creation and application of materials with extreme properties is continuously of great practical interest. These materials include also the aerogels (highly porous material with extremely low density and low thermal and electrical conductivity) developed by our research group. Novel materials enable also new and effective applications in technology.”

The article is focused in particular on organic aerogels produced from phenolic compounds obtained upon processing Estonian oil shale, i.e.  from local raw material. In order to produce highly porous aerogel from gel,  supercritical extraction with carbon dioxide is used, in the process of which liquid is replaced by gas resulting in aerogel –  a very light and porous material.

It is crucial that this aerogel is produced from local raw material, i.e. Estonian oil shale phenolic compounds,” Koel says. Due to the specificity of the compounds obtained from Estonian raw material, the reaction takes place quickly and at room temperature (earlier the production of aerogel required heating at a temperature as high as 100°C for a longer period of time). By doping these aerogels with metals, an excellent catalyst carrier is produced that can be used e.g. for waste water treatment.

Mihkel Koel said, “The study of the photocatalytic activity of organic aerogels doped with metals (Fe, Cu, Co, and Ni) produced novel and surprising results. The best results were obtained by using nickel (Ni).  Since aerogel is a highly porous material with large specific surface area, it is well-known for its excellent adsorbent properties, which is particularly important when acting as a catalyst. The article analyses photocatalytic degradation of substances in waste water. It appeared that this method can be successfully used e.g. for removal of the antibiotic trimethoprim, which is used to treat kidney infections, from waste water. Until now, cleaning water from pharmaceutical waste has been extremely complicated and not very effective.”

Mihkel Koel adds that the nanoporous materials research group studies also silica and cellulose aerogels and carbon aerogel produced at high temperature pyrolysis of organic aerogel (by heating up to 700-800 °C without air supply). When carbon aerogels are doped with metals, a material is produced that exhibits the best catalytic properties for electrolysis. In collaboration with the research group of a researcher from the Institute of Chemistry, University of Tartu, Kaido Tammeveski, a goal has been set for the future to use these catalysts in the development of low-temperature fuel cells.

Additional information:
Lead Research Scientist at the Division of Chemistry of the Department of Chemistry and Biotechnology of Tallinn University of Technology:  Mihkel Koel,

Chemical Engineering Journal, 02.2019

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