Silver nanoparticles will help to more effectively clean water from organic pollutants

(ORDO NEWS) — TPU scientists, together with colleagues from China, have found a way to modify a bismuth oxide-based photocatalyst for water purification by photocatalysis.

They synthesized a nanostructure that consists of a nonlinear optical material surrounded by bismuth oxide and silver nanoparticles. This made it possible to increase the efficiency of the catalyst.

The results of the study by specialists from the Research School of Chemical and Biomedical Technologies of TPU and the University of Electronic Sciences and Technology of China.

Photocatalytic technology lies in the fact that organic substances decompose on catalysts to carbon dioxide, water and other simple substances. This process is triggered by exposure to artificial ultraviolet or sunlight. Scientists are betting on the latter.

Cleansing under the influence of sunlight is especially effective for such organic pollutants as pesticides, estrogens, viruses. A catalyst is a substance that speeds up a process. At the same time, he himself is not consumed in the reaction process , that is, there is no need to continuously add chemicals to the purified water.

One of the effective photocatalysts for this technology is bismuth oxide: it is non-toxic, has a low cost and high chemical stability. But there are a number of factors that limit its effectiveness and use in practice.

Thus, a catalyst based on bismuth oxide can use only a small part of the light for catalysis – ultraviolet, while visible and infrared light do not participate in the process. Therefore, scientists set the task of modifying the photocatalyst in such a way as to use as much of the solar spectrum as possible in the catalysis process.

“Our group has accumulated rich experience in the properties and photocatalysis of silver nanoparticles. They have a little-known unique property – they absorb different colors depending on the size of the nanoparticles.

By choosing the optimal size, with the help of such particles it is possible to “catch” a significant part of the visible light. In addition, there are non-linear optical materials that are capable of converting infrared radiation into more energetic radiation – in the visible or ultraviolet range.

Nanoparticles capable of increasing the frequency of light were coated with bismuth and silver oxide nanoparticles. The synthesized nanostructure allows the catalyst to effectively interact with water due to its large surface area,” says Evgenia Sheremet, professor at TPU Research School of Chemical and Biomedical Technologies.

The effectiveness of the catalyst was tested on the experimental basis of colleagues from China, where they studied its ability to decompose the dye rhodamine B and the antibiotic tetracycline. Particles that combine all three elements – a particle that increases the frequency of light, silver and bismuth oxide, were the most effective.

“If the advanced technology is to be applied in practice, the industrial scale system will need to use a dedicated photocatalytic reactor.

There are two options for its functioning: either water is mixed with photocatalyst nanoparticles for more efficient operation, or the photocatalyst is fixed on a supporting substrate, such as a membrane or fibers, through which water is passed, ”comments another author of the article, professor at the Research School of Chemical and Biomedical Technologies TPU Raul Rodriguez.

Joint work on silver nanostructures continues. Now Tomsk scientists are studying the fundamental processes of photocatalysis on plasmonic nanoparticles and inexpensive methods for manufacturing such systems as part of the Priority 2030 program.

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