Igor N. Pyagay

This article presents a comprehensive study of saponite from the Arkhangelsk deposit and its organic modification. The crystal-chemical formula was calculated using chemical and thermogravimetric data. A three-dimensional structural model was constructed using VESTA to visualize the layered structure and cation distribution. Modification with dialkyldimethylammonium chloride (DADMAC) provided the highest hydrophobicity, with a contact angle of up to 87.66°, and the lowest interaction energy with hydrocarbons (0.031 J/m2). The Tanabe method revealed complete suppression of Lewis acid sites and an increase in Brønsted basic sites to 38.1% after DADMAC treatment. Textural analysis showed a significant increase in mesopore content (22.54–22.95%), and NMR spectroscopy revealed distinctive features of DADMAC-induced modification.

The composition and physicochemical properties of the delayed coking feed have a decisive influence on the qualitative characteristics of the resulting needle coke, which is formed both at the stage of liquid-phase thermolysis and at the stage of high-temperature calcination. In this paper, the effect of modification of hydrocarbon feedstock with polymeric mesogen additive on high-temperature calcination of needle coke in the temperature range of 600-1600 °С was studied. Changes in the structure formation of needle coke during high-temperature calcination as a function of feedstock modification and calcination temperature were determined by SEM, XRD, CHN, XRF and Raman spectroscopy, as well as by methods of complex study of physicochemical properties. At lower calcination temperatures (1200°C), needle coke from modified feedstock achieves a higher degree of carbonization compared to needle coke from unmodified feedstock (1400°C), which reduces the heat load on the calcining furnace while maintaining the quality of the resulting needle coke for the production of premium grades of graphite electrodes. Modification of needle coke raw material with polystyrene and calcination of the resulting raw needle coke at 1200°C provided the resulting electrodes electrical resistivity 7.1 (µΩ⋅m) and СTE20-520 = 0.897 * 10-6 K-1.

The demand for various types of zeolites in the oil and gas industry is associated with their high ion exchange and adsorption properties. This study is aimed to identify the regularities of the process of obtaining zeolite precursors from waste silica gel and industrial aluminium hydroxide since water glass and aluminate solution are the initial hydrogel components for the hydrothermal synthesis of zeolites. In addition, the process of hydrothermal synthesis of zeolites was investigated, namely, the effect of the molar ratio of SiO2:Al2O3 between hydrogel components on the structure and type of zeolite produced was determined. Identification of phases and study of the morphology of initial substances and obtained samples were carried out using X-ray diffraction and scanning electron microscopy methods. For the sample representing the monophase of LTA zeolite, the value of ion exchange capacity for Ca2+ ion and the particle size of the main fraction were determined to be 550 mEq/100g and less than 10 μm, respectively.

This article describes the results of a comprehensive comparative study of the production of fatty acid ethyl esters (FAEEs) for use as biodiesel in perfect mixing reactors (PMRs) and plug flow reactors (PFRs). The products obtained on a laboratory scale at all stages of the separation and purification of the FAEE phase were analyzed using the FTIR, XRF and GC-MS methods. We compared distillation methods for the separation of stoichiometrically excessive ethanol from the reaction mixture. Neutralization methods with H₂SO₄ solution and carbonation with CO₂ were applied for FAEE phase purification from the catalyst. Emulsions formed during the water flushing stage were analyzed via the optical microscopy method. The optimal conditions of stirring speed and temperature were selected to maintain a high level of FAEE–water phase contact area with minimum phase separation time. The efficiency of the carbonation method for catalyst neutralization in the FAEE phase has been proven, allowing us to consider this method as an alternative to the traditional acid neutralization method. According to the results of experimental studies, we have developed a new high-performance technological scheme for the production of fatty acid esters in PFRs. The synthesis of FAEEs in a stoichiometric excess of ethanol of about 1:50 allowed us to increase the reaction rate and productivity of the synthesis unit after the transition from a PMR to a PFR. The yield of the product amounted to 86.7%. The purified FAEE fraction complied with most EN14214 specifications.

This study explores the possibility of producing a sodium silicate solution (liquid glass) using industrial raw materials for subsequent use in metallurgical practice. The object of the study was industrial waste from the production of aluminium fluoride, i.e., silica gel, which comprises a fine powder of silicon dioxide with a moisture content of over 55 wt %. Silica gel was purified using a low-concentration solution of sulfuric acid. The synthesis of liquid glass was carried out using the HEL Auto-Mate Reactor System. The silicon content in the solution was determined by X-ray fluorescence method using the Shimadzu EDX-7000P analyzer. To determine the alkali content in the resulting product, a titrimetric analysis method was used. The preliminary purification process allowed silica gel with an amorphous silica content of over 98 wt % to be obtained. The optimal parameters of the liquid glass production were defined: temperature – 100°C, process time – 4.5 hours, mixing speed – 300 rpm, and the concentration of the initial alkaline solution – from 10 to 17.5 wt %. The resulting liquid glass solution had a mass content of silicon dioxide from 16.65 to 23.77 wt % and a silicate module from 2.72 to 3.16, which meets the requirements of marketable products for various industries. Based on the experimental results, optimal parameters for the production of liquid glass using industrial raw materials, i.e., silica gel, are proposed. Liquid glass with the defined characteristics can be further used as a binder in metallurgical processes.

Laboratorial production of agglomerate with basicity CaO/SiO2 = 1.3-1.5 is accompanied by its spontaneous friability, what leads to forming of visible cracks in agglomerate. When studying the influence of these sintering parameters on agglomerate strength, it is necessary to take into account content of not assimilated calcium oxides in sinter. Strength binding of agglomerate is formed on the base of calcium ferrites. Investigations were conducted on aluminium oxide of PA grade, Fe2O3, CaCO3 of PA grade, aqueous silicic acid of P grade. Stability of sinters for above-mentioned systems was determined visually and using high-frequency method. In the first case the hightemperature Tamman furnace is used, where briquetted samples are put in a platinum cup and they are heated up to the temperature 1300 °C. Then, after 5 minutes holding for homogenization, the samples are cooled slowly together with the furnace to the temperature 500 °C. To determine the temperature of β→γ transition of dicalcium silicate, dielectric permeability is measured; it reacts on structural changes which cause variation of density. The boundary of sinters stability is situated along the line which is close to galenite. The part of aluminium oxide interacts with dicalcium ferrite and forms solid solutions together with complete Fe replacement by Al in dicalcium ferrite. Stable sinters are characterized by monotonous variation of dielectric losses and capacity in the conditions of complete dicalcium silicate binding by aluminium oxide. It was established that monocalcium ferrite does not form new compounds with aluminium oxide, which completely interacts with dicalcium silicate. The stable samples of the system CaFe2O4–Ca2SiO4–Al2O3 are characterized by increase of alumosilicate amount and decrease of dicalcium silicate amount. When Ca2SiO4 content decreases from 45 % to 28 %, the temperature reduces from 390–405 °C до 265–275 °C. Agglomerate containing 7 % of alumina practically does not contain free calcium oxide, what removes the cause of stresses appearing in the sinter. As a result of stabilization of ferrite-calcium sinter via replacement of silicon module by aluminium one, compression strength value increases up to 235 daN for a briquette.

Countries around the world recognize the numerous social, economic and environmental advantages of promoting liquid biofuels. They invest in its development and introduce tax incentives for its manufacture and tariffs of production regulation. In most studies, the process of synthesizing fatty acid esters takes a long time from 1 to 8 h. In this work, the synthesis of fatty acid esters was carried out in the range of volumetric ratios of ethanol to linoleic type oil in order to increase the kinetics of the process. The main parameters of the synthesis were studied by use of magnetic stirred tank reactors in a parallel reactor system, H.E.L. The synthesis was carried out in the presence of a homogeneous alkaline catalyst. The volumetric ratio of ethanol to oil was maintained at 1:1, 2:1, 3:1, 4:1 and 5:1. The amount of catalyst added to the reaction mixture ranged from 0.25 to 2.5% by the weight of the reaction alcohol. The dryness of ethanol varied from 91 to 99%. Effective process conditions have been established to reduce the reaction time from 2.5 h to 5 min while maintaining a high degree of conversion. The results obtained during the study suggest the possibility of using a continuous reactor to produce fatty acid esters from linoleic raw materials containing up to 16% of free fatty acids. This also means the possibility of using second generation biofuel feedstock.

DOI: 10.31897/PMI.2023.1 The development of a comprehensive approach to preventing the pollution of natural objects is necessary due to the high requirements of environmental legislation for the discharge of industrial wastewater. Adsorbents are used in various industries to extract heavy metals from wastewater. In this study the possibility of using saponite clay as a...