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Scientists from the National University of Science and Technology and colleagues from the State University of Derzhavin Tambov and the State University of Saratov Chernyshevsky have discovered that Graphene is able to purify water, make it drinkable, without additional chlorination. The captured bacterial cells form flakes that are easy to extract from the water. Ultrasonically separated graphene can be reused. The article on research is published in Materials Science and Engineering C.
Graphene and graphene oxide (a more stable version of the material in colloidal solutions) are extremely promising carbon nanostructures for biomedicine. For example, it can be used for targeted drug administration at the graphene scale and for tumor imaging. Another interesting property of graphene and graphene oxide is the ability to destroy bacterial cells even without the additional use of antibiotics.
In the present study, the researchers injected graphene oxide into solutions (nutrient medium and saline) containing E. coli. According to the terms of the experiment, simulated saline water and nutrient medium simulate the human body. The results showed that graphene oxide as well as live and destroyed bacteria form flakes inside solutions. The resulting mass can be easily extracted, making the water almost completely free of bacteria. If the extracted mass is then sonicated, graphene can be separated and reused.
"As working solutions, we chose a nutrient medium for growing bacteria, as well as an ordinary saline solution, used for injections." E. coli modified with a luminescent agent was used to aid visualization experiences, "said contributor Aleksandr Gusev. .
Graphene oxide was added to the nutrient solution at different concentrations: 0.0025 g / l, 0.025 g / l, 0.25 g / l and 2.5 g / l. It turned out that even at a minimal concentration of graphene oxide in saline, the observed antibacterial effect was significantly higher than in the nutrient medium. Scientists believe that it is not a mechanism of action but of a biochemical nature. Since the saline solution contains much less nutrients, the bacteria moved more actively and were "captured" by graphene oxide scales more often.
According to the fluorescence test data, confirmed by laser confocal microscopy and scanning electron microscopy, at a concentration of 2.5 g / l graphene oxide, the number of bacteria decreased several times compared with control group and became close to zero.
Researchers believe that graphene oxide causes the formation of harmful free radicals for bacteria, although it is not yet clear exactly how the destruction of bacteria occurs.
According to scientists, if such a purification system is used for water, it will be possible to avoid additional chlorination. There are other advantages: decontamination with graphene oxide is inexpensive and this technology is easy to adapt to the format of major urban wastewater treatment plants.
GO paste makes graphene easy to shape and mold
Alexander Gusev et al, Effect of GO on bacterial cells: role of the type of medium and electrostatic interactions, Materials Science and Engineering: C (2019). DOI: 10.1016 / j.msec.2019.01.093
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Purify the water with graphene (April 29, 2019)
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