Teoretičeskie osnovy himičeskoj tehnologii

The qualitative and quantitative composition of NdFeB magnet has been established, the features of metal leaching by nitric acid solution have been studied. Optimal conditions of the process of the most complete leaching of metals were selected. A hydrophobic deep eutectic solvent based on di(2,4,4-trimethylpentyl)phosphinic acid (DTMPPA) and phenol was proposed as an extractant for the extraction of a series of metals from the nitric acid solution of neodymium magnet leaching. Experimental data on the extraction of Ni, Fe, Al and Cu ions from model individual and mixed solutions by deep eutectic solvent DTMPPA/phenol under varying key conditions of the process: acidity of the medium, concentration of the desalting agent, concentration of components in the eutectic solvent, metal concentration, etc. were obtained. The results obtained indicate the promising application of deep eutectic solvent DTMPPA/phenol for the extraction of Ni, Fe, Al and Cu cations in the processes of waste recycling of magnetic materials.

A comparison of thermal and ultrasonic intensification of supercritical fluid extraction using wild parsnip seeds, a source of plant oil and furocoumarin photosensibilizers, was conducted. It was observed that, even at pressure as high as 300 bar temperature effect on parsnip extraction demonstrates a so-called retrograde behaviour, that is, isobaric temperature increase leads decrease in extraction speed and overall mas yield. A previously proposed idea on a chromatography-like mechanism of a supercritical fluid extraction process with multiple re-adsorption of the isolated components onto the plant material working as a sorbent allows explaining the observance of retrograde behaviour, uncommon for such high pressure values. The overall influence of ultrasonic intensification of extraction process was shown to be similar to that of temperature. At low extraction pressure (100 bar), when cavitation of a subcritical fluid entering the extraction zone is principally possible, ultrasonication leads to an increased extraction kinetic at the initial, linear part of the extraction curve. At high working pressure (300 bar), effect of ultrasonication is essentially equal to that of direct heating. Using supercritical fluid chromatography, Furocoumarin profiles of thermal and ultrasonic parsnip extracts were shown to be identical by means of supercritical fluid chromatography, thus, ultrasonication even at 100 bar does not cause any unwanted sonochemical effects.

The work shows for the first time the possibility of using sorption technologies to separate a mixture of radioactive niobium and zirconium cations, which are part of the waste generated in the nuclear fuel cycle. The separation of these atoms will significantly reduce the costs of waste disposal, as well as provide an opportunity to reuse zirconium ions. In this work the process of ion separation using anion exchanger AB-17-8 is investigated in detail, conditions for more effective realization of the process under dynamic conditions are selected and its mechanism is proposed.

The results of mathematical modeling of the nonstationary problem of gas bubble surfacing in a viscous liquid with a solute dissolved in it are presented. The problem formulation is written taking into account the adsorption and desorption effects of the surfactant at the interface and the dependence of the surface tension coefficient on concentration according to Langmuir’s law. The numerical algorithm of the solution is based on the original Lagrangian-Eulerian technique, which allows us to explicitly allocate the free surface at the discrete level and realize natural boundary conditions on it. The process of establishing the stationary velocity of bubble surfacing is studied, and parametric research on the influence of the surfactant concentration and bubble size on the stationary velocity and flow structure in its vicinity is performed. The distributions of the velocity vector and surface concentration along the interface are presented, demonstrating the influence of the Marangoni effect on the surfacing process.

The paper presents an attempt to form a general approach to mathematical modeling of binary coalescence arising due to droplet deposition in a gravitational field based on the population balance equation, which can be further applied to predict the conditions of oil-water emulsion stratification. Using experimental curves of water content change over time in water-in-oil emulsions measured at different temperatures, four different ways of calculating the efficiency of binary coalescence are compared.

The problem of improving the accuracy of models for estimating the low-temperature properties, flammability and anti-wear properties of the target products of the fractionation column under conditions of a small amount of analytical control data is considered. For the solution of the considered problem the method of model building is proposed, which includes the algorithm of expansion of a small training sample on the data of fractional composition, differing in the way of selection of additional data, taking into account the sparsity indicator, which allowed to include the missing amount of data in the training sample, and as a result to ensure the improvement of the model quality. The use of the proposed method improved the accuracy of the models by 18% on average compared to the known methods and by 6% on average compared to the method based on the expansion of the training sample without taking into account the sparsity index. The results are presented on examples of model building of quality indicators of filterability limit temperature, flash point, kinematic toughness at 40°C and cetane number of middle distillate (diesel fuel fraction) and flash point of kerosene fraction of industrial fractionation column of hydrocracking process unit.