Russian scientists develop a smart sorbent for water purification
Scientists of the South Ural State University are engaged in the creation of a multifunctional carbon sorbent. The material will be able to absorb both several types of harmful substances produced in industrial production and selectively sorb individual organic substances. The original sorbent can be targeted at the most hazardous pollutants, the absorption of which will be a priority for it. On this topic, a scientific article was published in the journal Refractories and Industrial Ceramics.
Scientists have already patented a carbon sorbent of selective action in relation to phenol—an organic substance that has a toxic effect on the environment and human health. Phenol belongs to the second class of danger, easily penetrating the body through the skin and lungs, adversely affecting the functioning of the nervous and cardiovascular systems. The essential task that scientists set themselves is to develop materials that, in maximum volumes, "absorb" specific types of toxic impurities that enter the environment.
"We are engaged in carbon sorbents. According to modern concepts, the porous structure is responsible for their adsorption, i.e. macropores and micropores of the material. If the pore sizes are relatively equal to the size of the molecules, the material will obtain good sorbing properties. In other words, molecules of a harmful substance will penetrate into the structure of the sorbent and remain in it. However, the key problem is that molecules of various substances of a similar size are sorbed in one case and not in the other. In addition, if in one carbon material there are two pores of similar size, then in one of the adsorptions of some substance may occur, but in the other, adsorption is not observed. This is the main contradiction of the present theory," says Alexander Soldatov, candidate of technical sciences, assistant professor of life safety at the Polytechnic Institute of SUSU.
Scientists proceed from the assumption that the porous structure definitely affects adsorption, but the chemical structure of its surface considers the most significant contribution to the adsorption capacity of a carbon sorbent. Depending on the structure of the carbon material, it will exhibit sorbing properties in relation to a particular class of organic compounds to a broader or lesser extent.
In this regard, the scientific team studies various sorbents, evaluating their sorbing properties, and then chemically modifying the surface structure of the material. Next, a test of the sorbent is carried out, the purpose of which is to check whether the sorption capacity of the material has increased or not. As follows, the surface structure of the sorbent, as well as its porosity, determines the effectiveness of such a material when interacting with pollutants.
To date, experiments have been conducted with various harmful substances, including phenol, polyphenols, aldehydes, ketones, poly, and heteroaromatic compounds, and others. The study showed that each class of substances is absorbed by a sorbent with a various degree of intensity. In this regard, scientists set themselves another task.
"Under industrial conditions, a specific enterprise possesses a certain (rather limited) list of pollutants. Based on this, we can produce sorbents that will selectively sorb a certain group of components. Since the capacity of any sorbent material is limited, the priority for us is the absorption of the most environmentally hazardous substances. If the sorbent absorbs mainly some substances and excludes others, we will be able to more effectively clean, for example, water from the most harmful impurities. In other words, we will be able to regulate the selectivity of sorbents, generate them for the absorption of specific groups of substances "on order"," said Alexander Soldatov.
Sorption processes are used not only for solving environmental problems but also in industrial production. Therefore, the results of the study of carbon sorbents can find application both in securing the environment and in the production of various military and civilian products. It is known that carbon bond possesses exceptional strength, and carbon materials with the same strength are much lighter than most metals. In addition, carbon fiber reinforces and strengthens many composite materials. Another possible application represents the creation of new lithium sulfide batteries, which will be 20-30% more efficient than those currently used.
More information: A. I. Soldatov et al. The influence of carbon sorbent surface properties on adsorption poly- and heterocyclic aromatic hydrocarbons, NOVYE OGNEUPORY (NEW REFRACTORIES) (2019). DOI: 10.17073/1683-4518-2019-2-65-69
Provided by South Ural State University