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- Everything depends on a light bulb: in the Russian Federation, they have learned how to disinfect water using ordinary light
Everything depends on a light bulb: in the Russian Federation, they have learned how to disinfect water using ordinary light
Russian scientists have created a photocatalyst for water purification, which is activated by ordinary light from LED lamps. Currently, ultraviolet radiation from expensive and environmentally hazardous mercury lamps is used to disinfect water. According to the creators, their invention can be used to build new type of treatment reactors or integrated into existing systems. According to experts, the technology will be in demand if its economic advantages over the old approach are confirmed.
Water purification with ordinary light
A group of researchers from Skoltech has developed and patented a new photocatalyst that makes it possible to purify water from organic pollutants by irradiating it with visible light. Now this requires ultraviolet light, which is obtained from mercury gas-discharge lamps. However, they are environmentally hazardous and require special disposal. In addition, they disinfect the water unevenly.
— The radiation power of mercury lamps decreases significantly when the distance between the irradiated solution and the source increases, therefore, the concentration of ozone formed near the lighting device during disinfection of water can significantly exceed the permissible sanitary standards. We offer an alternative to mercury lamps — high-power UV-LED LEDs, which have the same advantages as conventional LED LEDs: environmental friendliness, cost—effectiveness, long service life and low power dissipation when removed from the source," said Ekaterina Moiseeva, author of the patent, intern researcher at the Center for Photonics and Photonic Technologies at Skoltech.
In classical technology, water first enters a reactor with a photocatalyst, which usually uses titanium dioxide (tio₂). Titanium dioxide nanoparticles are involved in the decomposition of water under the action of ultraviolet light. As a result, highly active hydroxyl radicals are formed, which mineralize chemical organic compounds and inactivate biological pathogens. However, titanium dioxide only absorbs UV radiation from mercury lamps. The scientists proposed using a hybrid composite with a phthalocyanine dye, which is activated by light from high-power LEDs.
Titanium dioxide (TIO₂)
— The principle of operation of titanium dioxide as a photocatalyst is based on its semiconductor properties. The key difference in the case of a hybrid material is that the photon absorbs phthalocyanine, and the resulting electron passes to titanium dioxide, and after that the already known mechanism is realized. The result is a photocatalyst for wastewater treatment that can function when exposed to visible light," said Dmitry Gorin, professor at the Skoltech Center for Photonics and Photonic Technologies.
According to the creators, the new photocatalyst is cheap and non-toxic, it has high chemical and mechanical stability. The technology is unique in that the purification of organic compounds occurs simultaneously with the disinfection stage. In this case, organic compounds are completely oxidized to carbon monoxide and water or mineralized. The photocatalytic reactor can be used both as an individual installation and as part of wastewater treatment systems in addition to the classic purification technologies — sand and coal filters.
Work on the photocatalyst was carried out in collaboration with the Department of Medicinal Chemistry, Faculty of Chemistry, Lomonosov Moscow State University.
Economic benefits
— The proposed water purification technology can be much more beneficial, since LEDs are much more durable than mercury lamps. When they burn out, replacing them is the biggest expense item for disinfection. Plus, you need to find a place to take them. They are also very fragile, and when destroyed, mercury infects the territory. In addition, the LEDs operate at low voltage," said Igor Shkradyuk, coordinator of the industrial greening program at the Wildlife Conservation Center.
If the ecological and economic efficiency of the technology is confirmed, it will open up wide application possibilities in industry, in everyday life, and even in such exotic areas as ensuring a closed water circulation cycle on a space station or water purification on an expedition, said Associate professor of the Department of Environmental Safety and Product Quality Management at the Institute of Ecology of the Rudn University. Patrice Lumumba Tatiana Ledashcheva.
According to Vladimir Pinaev, a member of the Public Council under the Ministry of Natural Resources of the Russian Federation, to evaluate the invention, it is necessary to calculate the price of using the technology, the availability of components for creating a purification system, as well as the environmental impact both during the extraction of components and the production of systems, and during their operation.
— Industrial testing on water of different composition and in different climatic and weather conditions, with different light intensity is also important; to determine the cleaning rate, the throughput capacity of the systems being designed, and so on, — said Vladimir Pinaev.
At the moment, the presented technology really looks very promising, but there may be pitfalls when implemented, the specialist emphasized.
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