No abstract

A significant increase in the amount of pollution (including heavy metals) that enter the hydrosphere as a result of human activity, sanitary requirements that are imposed on the quality of water, lead to the search for effective ways and methods of its purification. Wastewater from many industrial plants contain heavy metal salts, including manganese compounds. The sorption of manganese (II) cations by a composite sorbent from model solutions under static conditions was studied, to determine the possibility of using this sorption material in wastewater treatment. The characteristics of the sorption capacity of the composite sorbent are determined. It was established that the static exchange capacity of the composite sorbent is 0.9 mg/g; distribution coefficient - 47.34 l/g; the degree of purification of the solution is 99.9%. The empirical sorption equations for the manganese (II) cation are found, the sorption isotherms are constructed. It is established that the sorption process is described by the Freundlich equation. Experiments have shown that the composite sorbent is effective in extracting manganese (II) from aqueous solutions. Experimental data suggest that the sorbent studied can be used to clean industrial wastewater from manganese compounds.

A study of the influence of refractories’ structure on the thermomechanical properties of the lining of the equipment of tunnel kilns has been carried out. The lining of kiln trolleys is subjected to a mechanical stress distributed evenly over the entire area and the most dangerous to brittle materials, as well as to tensile thermal stresses. The magnitude of the tensile thermal stress depends on the material and the structure of the lining. The mechanisms of destruction of products made of fireclay and liquid concrete have been studied. Mineralogical and petrographic analysis of fireclay refractories have been used, as trolley lining has established metasomatic interaction of the lining with the vapor-gas component of the kiln, as well as with the metal of the trolleys. Monolithic products, made of low-cement concrete with corundum filler, are characterized by high strength and resistance to abrasion. The total value of compression and thermal expansion stresses for them is 3.08 MPa, which is half the value of those of fireclay. When conducting the research to optimize the composition of trolley lining, a technology for manufacturing two-layer concrete blocks, combining the advantages of compositions, based on corundum and fireclay, has been developed. The chemical and granulometric composition of fireclay-based concrete in the lower thermal insulation layer and electrocorundum-based concrete in the upper reinforcing layer were selected in such a way, as to ensure similar values of linear thermal expansion coefficients and prevent possible destruction along the boundary between the layers during the operation.

Although copper is needed for living organisms at low concentrations, it is one of the pollutants that should be monitored along with other heavy metals. A novel and sustainable composite mineralizing sorbent based on MgO-CaO-Al2O3-SiO2-CO2 with nanosized adsorption centers was synthesized using natural calcium–magnesium carbonates and clay aluminosilicates for copper sorption. An organometallic modifier was added as a temporary binder and a source of inovalent ions participating in the reactions of defect formation and activated sintering. The sorbent-mineralizer samples of specified composition and properties showed irreversible sorption of Cu2+ ions by the ion exchange reactions Ca2+ ↔ Cu2+ and Mg2+ ↔ Cu2+. The topochemical reactions of the ion exchange 2OH− → CO32−, 2OH− → SO42− and CO32− → SO42− occurred at the surface with formation of the mixed calcium–copper carbonates and sulfates structurally connected with aluminosilicate matrix. The reverse migration of ions to the environment is blocked by the subsequent mineralization of the newly formed interconnected aluminosilicate and carbonate structures.

In recent years, the Russian Federation has paid more attention to protecting the environment from the negative impact of various pollutants. The goal of the Closed Loop Economy federal project, for example, was to stimulate the use of recyclable material. The agro-industrial complex produces a huge amount of waste during the processing of crops. One of these wastes is buckwheat husk. There are a number of studies proving the application of buckwheat husks in large quantities as a sorbent for certain wastewater treatment methods. However, the low strength of husk leads to a number of technological difficulties in operation. The goal of this study is to increase the performance of buckwheat husks through granulation and evaluate the sorption capacity of granulated buckwheat husks when treating urban surface runoff. In this study we used granulated buckwheat husks produced in a method analogous to fuel pellets. Tests were run on real runoff collected from storm sewers in Chelyabinsk. We determined that granulated buckwheat husks effectively remove pollutants from runoff. In static conditions at a temperature of 10C to 20C, aluminum was most effectively sorbed upon contact with the sorbate over 168 hours (94.12%). At 0C, slightly less aluminum was sorbed (82.35%). Cobalt, chromium, copper, and zinc are completely extracted from runoff after 3 hours of sorption, regardless of temperature changes.In dynamic test conditions, we determined that the buckwheat husk granules totally extract heavy metals (cobalt, chromium, copper) from storm drain runoff. The concentration of aluminum cations was reduced to 68%. Lower concentrations of sodium and silicon cations were also noted.