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2021, №4

pp. 4-13

Articles

Key words: hypercrosslinked polystyrene, supercritical carbon dioxide, metal compounds, supercritical fluid chromatography, adsorption, di phenylacetylene, specific catalytic activity

Metal — hyper-cross-linked polystyrene (HCP) composites active in the hydrogenation of unsaturated hydrocarbons were obtained by impregnation of HCP with palladium and rhodium compounds in supercritical carbon dioxide (SC-CO2) followed by their reduction to the metallic state with molecular hydrogen. The influence of the conditions for the preparation of composites on their activity and selectivity in the hydrogenation of diphenylacetylene (DFA) was evaluated. The adsorption of palladium hexafluoroacetylacetonate on HCP from the SCCO2 medium was studied for the first time using supercritical fluid chromatography; it is shown that the adsorption equilibrium is described by the Langmuir equation.

doi:10.34984/SCFTP.2021.16.4.001

2021, №4

pp. 14-26

Articles

Key words: aluminum oxide, group II metal compounds, water fluid, ammonia, aluminates, heat treatment

The formation of mixed oxides in the Al2O3—MO (M — Mg, Ca, Sr, Ba) system during heat treatment and treatment with water fluids (WF) has been studied. It is shown that during high-temperature treatment of mixtures of aluminum hydroxide Al(OH)3 with nitrates of metals of group II, aluminates of the composition MAl2O4 are formed mainly, sometimes with an admixture of aluminates of a different composition. If the same mixtures undergo preliminary treatment in a water fluid (400 °C, fluid density 0,2 g/cm3), then the sample is more complex, which is associated with dehydration and partial structuring of the Al-containing component during processing in a WF medium. It is shown that the addition of ammonia to WF has a stimulating effect on the formation of double oxides, first of all, due to the alkaline hydrolysis of salts of II group metals and the formation of corresponding hydroxides; the reduction of nitrates and nitrites with ammonia is apparently a secondary process.

doi:10.34984/SCFTP.2021.16.4.002

2021, №4

pp. 27-33

Articles

Key words: Mo—V—Nb—Te—O-catalysts, oxidative dehydrogenation, ethane, ethylene, molecular oxygen

The process of oxidative dehydrogenation of ethane (ODE) at elevated pressure on mixed oxide catalyst MoVNbTeOx has been investigated. It was found that when the reaction is carried out at 280 °C with an increase in pressure from 0,1 to 10,0 MPa, the proportion of the total amount of reacted oxygen consumed for the formation of ethylene decreases from 100 to 68 %, which may indicate an increase in the role of chemisorbed oxygen in the ODE process at high pressure. In this case, the productivity for ethylene at 280 °C and 10,0 MPa higher compared to the value obtained at 360 °C and 0,1 MPa.

doi:10.34984/SCFTP.2021.16.4.003

2021, №4

pp. 34-41

Articles

Key words: salmeterol base, salmeterol xinafoate, supercritic fluid chromatography, enantiomers

The physicochemical features of the chiral separation of isomers of salmeterol xinafoate and salmeterol base were studied by supercritical fluid chromatography (SFC) in analytical and preparative modes. The influence of the composition of the mobile phase, temperature and pressure on retention, peak shapes and selectivity of chiral separation of the salmeterol base racemate in the analytical chromatography mode was studied. The optimal conditions for the separation of the enantiomers of salmeterol base on an analytical column Chiralpak IG in supercritical CO2 (SC-CO2) have been revealed. The behavior of salmeterol xinafoate was studied under conditions of preparative SFC analysis.

doi:10.34984/SCFTP.2021.16.4.004

2021, №4

pp. 42-55

Articles

Key words: fluorinated tetraphenylporphyrins, MF-4SK copolymer, photosensitized cholesterol oxidation

The immobilization of fluorinated tetraphenylporphyrins in the matrix of the sulfocathionite perfluorinated copolymer MF-4SK and the photosensitized oxidation of cholesterol in the presence of obtained composite were carried out in the supercritical (SC) carbon dioxide medium. It is shown that the reaction proceeds with the formation of 6-formyl-B-norcholestane-3β,5β-diol (a potential antitumor agent), in contrast to the homogeneous photooxidation of cholesterol, where main product is 7α-hydroperoxide-3β-hydroxycholest-5-ene. A reaction mechanism has been proposed, which assumes the process takes place inside the «ion channels» of MF-4SK.

doi:10.34984/SCFTP.2021.16.4.005

2021, №4

pp. 56-69

Articles

Key words: phenol, activated carbon, adsorption, desorption, regeneration, sub- and supercritical water

The paper presents the research results of dynamic adsorption of phenol by activated carbon (AC) in the medium of liquid, sub- and supercritical water (26 °C, 0.1 MPa and 24—400 °C, 25 MPa) and subsequent regeneration of AC under similar conditions. It is shown that the adsorption—desorption isotherms are characterized by the presence of hysteresis. An increase in pressure at room temperature leads to an increase in the adsorption capacity, and an increase in temperature at 25 MPa leads to a decrease in it. The amount of phenol remaining in the AC after regeneration decreases with increasing temperature and does not depend on pressure. The relative average rate of phenol desorption increases sharply at T ≥ 200 °C. It was found that the greatest increase in the specific surface area and pore volume occurs when AC is treated with supercritical water.

doi:10.34984/SCFTP.2021.16.4.006

2021, №4

pp. 70-82

Articles

Key words: subcritical water, extracts of Ginkgo biloba leaves (Ginkgo biloba L.), polyphenols, flavonoids, inhibitory AChE-activity, Alzheimer’s disease

The extracts of Ginkgo biloba (GB) leaves obtained in a medium of subcritical water (SBW) in the temperature range of 100 °C—220 °C were studied for the first time in order to assess the prospects for the use of GB leaf extracts for the prevention and treatment of neurodegenerative disorders, such as, for example, Alzheimer’s disease. The relationship of the activity of inhibition of the enzyme acetylcholinesterase (AChE) with the content of polyphenols and flavonoids was studied. The inhibitory activity of GB leafn extracts was expressed as IC50 values (an extract concentration that inhibits the AChE enzyme by 50 %), determined by dose-effect curves. It is shown that the content of polyphenols and flavonoids in the extracts obtained, and the inhibition activity of AChE extracts depends on the extraction method: if the traditional aqueous-ethanol extract has an anti-AChE-activity of IC50 = 3.57 mg/ml, then SBW- extracts are more effective inhibitors of AChE. At the same time, the maximum inhibitory activity of AChE, in a number of extracts obtained, was demonstrated by an extract obtained in the medium of SBW at 220 °C (IC50 = 0.74 mg/ml). At the same time, the AChE-activity of the obtained extracts of GB leaves correlates with the quantitative content of the sum of polyphenols and flavonoids, respectively. The total content of polyphenol (the sum of polyphenols per gallic acid or rutin) was highest in the extract obtained in medium of SBW at 220 °C, whereas the extract obtained at 100 °C in SBW was the lowest in content of polyphenols. The total content of flavonoids (in terms of rutin) was highest in extracts obtained in medium of SBW at 200—220 °C (24.6 mg equivalent to rutin/g dry weight of raw materials), and the lowest content in GB leaf extract obtained in SBW at 120 °C (10.6 mg rutin equivalent/g dry weight).

doi:10.34984/SCFTP.2021.16.4.007

2021, №4

pp. 83-87

Articles

Key words: cruciate ligament prosthesis, decellurization, supercritical fluid, biocompatible material, collagen frame, xenogenic materials

A prototype of a cruciate ligament (ACL) prosthesis from a lamb tendon was created. For the manufacture of this product, a raw material processing technology was developed, including mechanical and chemical-physical methods, including exposure to a supercritical fluid of carbon dioxide, with a nonionic surfactant Tween 80 for decellularization, that is, destruction of cells and extraction of their components with immunogenic properties, as well as the removal of residues of toxic substances after treatments, while maintaining the physical and mechanical properties. Histological studies were carried out for the remainder of cellular elements and measurements of the strength properties of the material and it was shown that the cells were removed, and the physical and mechanical properties did not deteriorate.

doi:10.34984/SCFTP.2021.16.4.008