Natural mineral that cleans the soil from oil
More than 1.5 million hectares of the country's territory are polluted with oil and oil products. The volume of black gold exported to the steppe exceeds 50 million tons. Science has solved many problems in the way of mankind. In this regard, KazNU scientists, based on several years of research, offer the most effective way.
Currently, there are many ways to clean the soil from oil. Most of them are expensive, based on complex processes, and the reagents used in the process are not available. That is why cheap, effective cleaning methods are of interest to the population. One of them is the sorption method. Therefore, KazNU scientists have developed sorbents based on shungite rocks from the Koksu deposit. According to the head of the project, Professor of Chemical Physics and Materials Science, Doctor of Chemistry Erdos Ongarbaev, the main advantage of this is the opportunity to clean up the land polluted with oil waste at the final stage. That is, this method is used when the amount of oil in the soil does not exceed 5-10%. And this allows you to control the process, preventing secondary pollution.
Shungite is a natural mineral or a mineral mined in the eastern and southeastern regions of the country. Produced in Russia on the territory of Karelia. Sorbents from shungite of the Karelian deposit are 1.5-2 times cheaper than coal and are effective as a filter element, catalyst, and bio-disinfectant. This conclusion was reached during industrial tests of wastewater treatment. Shungite reserves at the Koksu deposit in the Almaty region are estimated at 620 million tons.
According to the professor, the peculiarity of shungite is that it contains oxides of carbon and silicon, which provide its high sorption properties.
- Usually the usual sorbent - activated carbon contains only carbon, and shungite contains oxides and compounds of silicon and other elements. We all know that the scientists of the faculty have previously developed and introduced into production filter materials that purify water from various harmful substances based on shungite. The novelty of our project is the immobilization of strains of microorganisms on a shungite-based sorbent and, for the first time, the use of soil for treating oil spills and oil products, E. Ongarbaev said.
The "signature" of civilization can be seen in many environmental issues. Moreover, as industry grows, we observe a decrease in natural processes in the environment. The spread of black gold in the soil during oil production, collection, transportation, storage and preparation, well repair has become an environmental problem. Oil is one of the most dangerous pollutants. Because it negatively affects the development of living organisms and plants in the soil.
In recent years, natural sorbents have been used in industry. The main factor influencing this is the widespread use of sorbents in nature. That is why the cost is low. In addition, they have high sorption properties and simple application technology. These minerals and natural raw materials can be used in various industries.
Shungite allows you to purify water from oil and salts of heavy metals. Because its basis is shungite carbon. The structure of shungite carbon is similar to fullerene, i.e. it has an ordered structure, and also contains aluminosilicates, alkali metal oxides, and trace amounts of rare metals.
As mentioned above, today there are many ways to clean the soil and water from oil. Let's take a look at some of them for comparison. For example, there is a sorbent consisting of a suspension of glauconite and bentonite clays in a ratio of 1/3 and 3/5, enriched with glauconite and fullerenes with shungite. Due to its low oil content, it is ineffective and does not increase the number of native oil-oxidizing microorganisms.
To obtain the following types of sorbents, a mixture of shungite and lignin hydrolyzate is heated to 100°C and carbonized by raising the temperature to 700°C in argon or nitrogen. To obtain a sorbent consisting of shungite and rice husks, the mixture is heated to 150°C, dehydrated at 150-200°C and carbonized at 200-400°C in argon or nitrogen. The disadvantage of these sorbents is that at the initial stage the raw materials are processed in several stages and high temperatures are used.
Another type of sorbent is recommended for cleaning oil-contaminated soils. It consists of zeolite, shungite and potassium humate. They are introduced into the soil in a certain order: first shungite and potassium humate are mixed, then zeolite a week later, and then treated soil every two weeks. Reading the process, you can see the shortcomings of this composition. Because re-cultivation of the soil, the use of additional reagents will require more resources.
Shungite rocks can be used as an enterosorbent to cleanse the body of toxins and microorganisms. For example, one can find an enterosorbent consisting of shungite rock with particles of 15.0·10-6 µm and 50-70% by weight of silicon dioxide. However, there is no information about how its use affects the sorption of microorganisms. In addition, the enterosorbent, consisting of shungite rocks of the same size and 20-50% by weight of silicon dioxide, affects the adsorption of microorganisms, but in general, the sorption capacity is insufficient.
In addition, heat-treated shungite at 500-550°C can purify liquids as a sorbent. But for this it is necessary to process the raw materials at a high temperature.
Scientists of KazNU develop sorbents by mechanochemical activation of shungite rocks of the domestic Koksu deposit. As a result, sorbents have a nano structure that improves sorption properties by increasing surface area, porosity, and porosity. “Thus, we can increase the efficiency of the process of cleaning the soil from oil residues,” said Erdos Kalimollaevich.
Nanotechnology is the production of nanosized materials with special properties and their use in various directions. When the particle size of the material is less than 100 nanometers, their physicochemical, mechanical and other properties are better than usual. Erdos Ongarbaev expressed hope that the project will improve the sorption properties of shungite samples to such a nano scale.
- Until now, we have obtained nanostructured materials by grinding shungite by mechanochemical activation, as well as by roasting with rice husks. Microbial strains isolated from oil-contaminated soil were placed on these materials, and the degree of their oil degradation was determined, the value of which reached 70-80%. This work is carried out on the basis of the Department of Chemical Physics and Materials Science and the Institute of Combustion Problems together with scientists from the Department of Microbiology of our university. In general, the grant project is designed for implementation in 2020-2022. Therefore, next year we will start cleaning samples of real contaminated soil, the scientist said.
The proposed project will increase the mass of native oil-oxidizing microorganisms and, accordingly, obtain a sorbent that will increase the degradation of oil and oil products in the soil. As a result, microorganisms that multiply in the soil feed on oil hydrocarbons and convert them into carbon dioxide and water. And sorbents on the surface additionally contribute to the growth of plants as fertilizers. Therefore, used sorbents do not need to be collected or recycled.
Sorbents based on shungite rocks of the Koksu deposit enhance the destruction of oil and oil products in the soil. This is economically beneficial for the domestic oil industry.
This project is supported by the mining company Koksu. The main goal is to expand the use of shungite in Kazakhstan. And this company is ready to provide the necessary assistance in the implementation of the project. These studies are of great scientific importance. Because it helps to obtain new information about the properties and structure of sorbents, the mechanism of sorption of oil and oil products.
The natural sorbent of the Koksu shungite deposit has the properties of coal and silicate adsorbents. That is why it has a high oil absorption. Since alien hydrocarbon-oxidizing microorganisms are not introduced into the soil, the natural biocenosis remains the same. This is an effective way to break down the oil. The use of such a sorbent does not adversely affect the beneficial microbiota of oil-contaminated areas.
CAMILA DUYSEN
