Том 53, № 4 (2019)

A comprehensive formulation for the problem of engineering applied to a multistage chemical energotechnological system for the production of phosphorus from the technogenic wastes of apatite-nepheline ores is presented. The main objective of the studies performed within the procedure of engineering is to determine the phosphorus-production technology parameters decreasing energy and resource efficiency due to the optimization of energy-consumption values for all considered multistage chemical energotechnological processes instead of individual stages. A generalized model of engineering is developed for the chemical energotechnological system of phosphorus production in compliance with the IDEF0 International Standard of Function Modeling, and parameters suitable for further use in the procedure of minimizing the energy and resource efficiency of this production are concretized for multistage chemical energotechnological processes. A conceptual foundation based on the methods of automatic control theory, i.e., the state-space description of control objects, is proposed for the creation of a universal program-optimization model for a chemical energotechnological system. Some results of a simulation experiment in the Simulink environment for the modeling of dynamic systems are presented to demonstrate the applicability of the proposed approaches to the optimization of multistage chemical energotechnological processes.

The results of generalizing the solubility of aromatic hydrocarbons in supercritical carbon dioxide using the entropy method of similarity theory are presented. Experimental data from different authors on the solubility of 11 substances studied in a temperature range from 300 to 350 K (728 experimental points and 50 isotherms) are subjected to generalization. It is shown that the dependency makes it possible to compute the solubility of aromatic hydrocarbons subjected to generalization in supercritical carbon dioxide to an acceptable accuracy.

The calculation of the number-average degree of polymerization is considered exemplified by the radical polymerization of styrene, which is carried out at 343, 348, and 353 K. The system of differential equations on the graph using corrections specified as formulas has been applied for the calculation. When using the minimum set of initial data, the error of the calculated and experimental values is 40, 33.3, and 37.5% at 343, 348, and 353 K, respectively. The inverse kinetic problem has been solved.

Experimental data on the flow boundaries of a barite suspension depending on its concentration and volume flow rate for a 10 mm high-pressure hydrocyclone were presented. Computer simulation of phase separation in the high-pressure hydrocyclone was performed for a concentrated suspension. Qualitative agreement between the results of numerical modeling and experiment on the conditions of clogging of the hydrocyclone underflow was obtained.

The influence of characteristics of ligands and nickel complex compounds on the rate of the autocatalytic (chemical) deposition of nickel–phosphorus coating and the phosphorus content is considered. It has been established that the charge and complex of the ligand have the highest effect on the rate of process, and charge number and stability of the complex ion have the highest effect on the content of phosphorus in the coating. Mathematical models describing the relationship between the deposition rate, the composition of coatings, and the corresponding ligand parameters are obtained. Recommendations for the selection of the ligand composition of solutions for the chemical deposition of nickel–phosphorus alloy are proposed.

The specific features of gas hydrate formation during the injection of liquid carbon dioxide into a porous medium saturated with methane and water with allowance for the boiling of carbon dioxide have been studied. It has been found that the formation of carbon dioxide hydrate can occur both on the frontal boundary and in the extended region. It has been shown that the boiling of carbon dioxide and the corresponding cooling of a reservoir facilitate the formation of carbon dioxide hydrate on the frontal surface. Curves have been constructed that separate different regimes depending on injection pressure, initial pressure, and reservoir permeability.

Three distinct agricultural waste materials, viz., casuarina fruit powder (CFP), sorghum stem powder (SSP), and banana stem powder (BSP) were used as low-cost adsorbents for the removal of toxic lead(II) from aqueous solutions. Acid treated adsorbents were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR). The effects of parameters like adsorbent dose, pH, temperature, initial metal ion concentration, and time of adsorption on the removal of Pb(II) were analyzed for each adsorbent individually and the efficiency order was BSP > SSP > CFP. Based on the extent of compatibility to Freundlich/Langmuir/Dubinin–Radushkevich/Temkin adsorption isotherms and different models (pseudo-first and second order, Boyd, Weber’s, and Elovich), chemisorption primarily involved in the case of BSP and SSP, whereas simultaneous occurrence of chemisorption and physisorption was proposed in the case of CFP which was correlating with the thermodynamic study results conducted at different temperatures. Based on the observations, it was proposed that three kinetic stages involve in the adsorption process, viz., diffusion of sorbate to sorbent, intra particle diffusion, and then establishment of equilibrium. These adsorbents have a promising role towards the removal of Pb(II) from industrial wastewater to contribute environmental protection.

Calcium formate is widely used in construction, tanning, and textile manufacture and as an E238 biological additive in cosmetology and the food industry. It has been shown for the first time that calcium formate can be produced from sodium formate according to the reaction CaAn₂ + 2HCOONa \( \rightleftarrows \) (HCOO)₂Ca + 2NaAn in an aqueous solution. The solubility in CaAn₂–HCOONa–H₂O (An^– is chloride or nitrate) ternary systems at 25°C has been studied.

Granulated inorganic sorbents based on KSKG silica gel and aluminum oxide modified with Fe(III) compounds were developed for water purification from As(V). Physicochemical properties of synthesized sorbents were studied. It was discovered that the dynamic exchange capacity for As(V) varied in the following series: Al₂O₃–7Fe–Amk-290 < SiO₂–7Fe–Az < SiO₂–7Fe–Ox < SiO₂–7Fe–Amk-290 < Si₂–7Fe–Amk-600.

The phase equilibria at 0 to –22°C in the sections of a carbamide–sodium formate–water system with ratios CO(NH₂)₂ : NaHCOO from 3 : 1 to 1 : 3 and anti-icing properties of salt compounds are studied. It is found that a compound with ratio of 1 : 1 has a temperature of the eutectic with ice of –22°C; i.e., it significantly decreases in comparison with the temperatures of the eutectics in binary systems containing carbamide or sodium formate. The compounds are characterized by a high melting capacity in relation to ice.

The results of a study of the structural–mechanical properties of granules of various types of mineral fertilizers prepared on the basis of ammonium phosphates by measuring the force necessary for the destruction of the granule upon uniaxial compression between two parallel planes and deformation along the compression axis are given. Using X-ray microtomography and raster electron microscopy, the structure of granules is studied. The results of the calculation of the coefficient of local stress concentration, as well as activation energy of destruction and strength of the granules, are given.

Thin-film nanostructured coatings have been produced electrolytically from TiO₂ codoped with nitrogen and fluorine. The resulting films consist of individual TiO₂ nanotubes with the polycrystalline anatase structure; they are characterized by narrow size distribution and a high degree of local self-organization. Diffuse reflectance spectroscopy demonstrates that the absorption edge of the samples codoped with nitrogen and fluorine is shifted towards the longer wavelength region of the solar spectrum by 200 nm with respect to pure TiO₂. When irradiated with visible light, the synthesized TiO₂ films exhibit high photocatalytic activity in the reaction of phenol oxidation in aqueous media.

Findings from a study of the N₂O absorption from an air flow in various aqueous and organic solutions at 293–298 K were reported. The maximum N₂O absorption reached under the experimental conditions for water (~22–24%) and a saturated solution of K₂Cr₂O₇ in concentrated H₂SO₄ with and without Al₂O₃ (~34 and ~30%, respectively) was determined. In concentrated HNO₃ and NH₄OH solutions, as well as in 1.0 mol/L NaOH and N₂H₄ ⋅ nH₂O solutions, the degree of the N₂O absorption varied within a range from ~7.5 to ~11.5%. A similar value of absorption was also found in 0.5 mol/L (NH₂)₂CO (~11%). In other solutions, the degree of the N₂O absorption was not more than ~4.0%. In the studied organic solutions, the degree of the N₂O absorption was found to be less than ~12%.

The effect of a humate reagent obtained from oxidized brown coal and sodium oleate on the wettability of minerals present in the composition of fluorite ores such as fluorite, calcite, and quartz is studied. It is shown that, in the case of successive treatment of fluorite and calcite with a humate reagent and sodium oleate, the difference in the wettability of the minerals significantly increases, which promotes the selection of these minerals during flotation.

This work presents the results of experimental studies of leaching aluminosilicate and quartz impurities from leucoxene from the Yaregskoe deposit by sodium hydroxide solution by sodium hydroxide solution. According to the data, the type of kinetic equation of SiO₂ dissolution is defined, as are the equation parameters, including the orders by the reagents, the preexponential factor, and the activation energy. The activation energy of 77.2 ± 3.9 kJ/mol corresponds to the kinetic region of the reaction behavior.

Research results on the behavior of Fe, Cu, Zn, Cd, K, and Na by operations of solvent extraction technology of rhenium recovery from washing sulfuric acid of copper production and industry-related solutions with obtaining technical ammonium perrhenate as well as by technical salt recrystallization products were presented. Recommendations on decreasing of content of elements-impurities in pure salt were provided.

The behavior of carbon in reactions of the synthesis of mixed nitrides of uranium and plutonium is determined not only by its excess content against stoichiometry, but also by the active influence of hydrogen and nitrogen as components of technological gas. It is also necessary to account for the impact of products of thermolysis of the binder. The results of a thermodynamic analysis of possible reactions during synthesis indicate the special behavior of phase UC_1.91 in the process and bring up additional questions on the mechanism of removal of excess carbon under temperatures of synthesis.

Instrumental and technological methods of intensifying the processes of heat and mass transfer in the column reactors with a packing are considered. It has been shown that one of the most promising areas for increasing the intensity of heat- and mass-transfer processes is the operation of a multilayer packing apparatus at gas flow rates close to the rate of suspension of the liquid phase.

A ceramic porous filler obtained from intershale clay and oil sludge, which are pollutants in the environment, is the object of this study. The distribution of iron ions is revealed during the firing of the porous filler with a Mossbauer effect. The transformations of ferrous compounds in redox processes on the surface and in the middle of the samples containing high amount of iron oxide are considered. The experiments showed that the calcined ceramic samples have a zonality: the surface of the samples containing less than 6% of Fe₂O₃ is lighter than that of the inside part, the surface of the samples containing more than 8% of Fe₂O₃ is light cherry in color, and the interior part is dark cherry in color. The proposed composition for the production of a porous filler is innovative to decrease the negative impact of toxic wastes on the environment, the novelty of which is protected by a patent of the Russian Federation.