Home – Home – Jornals – Chemistry for Sustainable Development 2019 number 4

The article summarizes the results obtained in the studies of the distribution of thiocyanate acid complexes of iron (III), copper (II), cobalt (II), zinc and cadmium in extraction systems based on technical surfactants - potassium bis(alkylpolyoxyethylene) phosphate (oxyphos B) in the presence of sulphuric acid, alkylbenzyldimethylammonium chloride (catamin AB) in the presence of nitric acid at room temperature or their mixture at 50 ºC. It was established that the efficiency of individual surfactants as extractants is conserved both with inorganic salts and acids used as salting-out agents. It is shown that for oxyphos B extractability decreases as a sequence Fe(III) > Co(II) > Zn > Cu(II) > Cd, while for catamine AB the sequence is Cd ≈ Zn > Co(II) > Cu(II) > Fe(III), and in the case when a mixture of surfactants is used, oxyphos B is determining, which is confirmed by the extractability sequence: Fe(III) > Co(II) > Zn > Cu(II) > Cd. Oxyphos B is an analog of neutral oxygen-containing extractants, it concentrates thiocyanate acid complexes according to the hydrate-solvate mechanism, while catamin AB, anion-exchanging extractant. is more efficient in the extraction of thiocyanate complexes. The use of a mixture of the indicated surfactants allows one to carry out the process in more diluted solutions and to obtain synergetic effects in extraction.

The cobalt content of nanostructured powders obtained by means of the hydrothermal treatment of the aqueous solutions of Sn (II) and Co (II) chlorides is studied using two spectral methods - energy-dispersive (EDS) and atomic absorption (AAS). Liquid samples for atomic absorption analysis were prepared along two routes: by boiling the products of hydrothermal synthesis in concentrated acids and by fusing the products of hydrothermal synthesis with a mixture of sodium peroxide and borax, followed by diluting the liquid alloy. It is shown that low-temperature alloying of samples is most preferable to determine cobalt concentration in ferromagnetic Sn_1-xCo_xO_2-δ nanostructures. Results obtained in the present work allow us to better understand the process of the formation of Сo-doped SnO₂ nanostructures and use these structures to develop new functional materials.

The review examines the pharmacological effects of 4-(hydroxyethyl)phenol ( p-tyrosol) and its metabolite 2-hydroxytyrosol in acute ischemic disorders of the cardiovascular system and cerebral stroke. The antithrombotic, antioxidant, anti-inflammatory and antiarrhythmic activity of this compound is discussed in detail, its antimicrobial, anti-cancer and anti-metastases effects are noted. p-Tyrosol contributes to the creation of a new vascular system in the affected area (neoangiogeses), which leads not only to the restoration of blood supply in the organ affected by ischemia, but also improves geodynamics in the whole body. Studies in animals have proven the effectiveness of parenteral administration of p -tyrosol in the preoperative period of exacerbation of heart ischemia and stroke of the brain. The use of this substance leads in most cases to arresting arrhythmias and thrombosis, has a beneficial effect on the nervous system, which generally helps to reduce the area of damage to the heart and other organs with ischemia, significantly increases the number of surviving animals. The positive effect of plants containing p- tyrosol and its derivatives on the human cardiovascular system is considered, along with pharmacokinetics and the routes of the introduction of these phenolic compounds into the organism at different stages of ischemia.

The acute and chronic toxicity of several chemical reagents based on surfactants and used to treat oil-contaminated soils and sludge was evaluated. Biotesting based on the response of invertebrates and higher plants allowed us to conclude that the tested chemical reagents can be applied with effective concentrations which are safe for ecosystems. The effective concentrations were established for the phytoeffects of inhibiting the growth and development of two types of test plants (oil radish - Brassica rapa CrGC syn. Rbr, and cultivated oat - Avena sativa L.) and for the survival ability of the standardized test culture of Paramecium caudatum Ehrenberg.

The processes involved in obtaining iron-free X-ray amorphous aluminosilicate raw material of the required composition from the ash and slag waste (ASW) from the combustion of brown coal of KAFEC are investigated. Carbon thermal reduction during ASW melting is used to extract iron and its compounds. The distribution of elements - iron (Fe²⁺, Fe³⁺, Fe⁰, Fe^tot), sulphur (S) and carbon (C) - in the metal (magnetic) and silicate (nonmagnetic) fractions at different temperatures of ASW heating is shown. The equations describing the temperature dependence of the standard change of Gibbs energy for the reactions of the reduction of iron oxides are presented. The effect of silicon carbide, formed in the silicate fraction of the melt, on the recovery of iron oxides to metal iron and the resistance of foam formed due to the reducing gases are discussed. The introduction of the melt into water changes the morphology and leads to the formation of foamed heat-insulating material. Normalization of the charge during melting allows obtaining foamed materials of the required composition.

Metal matrix composite powders based on titanium carbide with titanium and high-speed steel as binders were studied by means of X-ray diffractometry, scanning and transmission electron microscopy. The composite powders were obtained by crushing the cakes formed as the products of self-propagating high-temperature synthesis (SHS) from titanium, carbon (black carbon) and HSS powder mixtures, followed by mechanical treatment in a planetary ball mill Aktivator-2S. It was stated that disintegration rate depends on metal binder content in the SHS product. To obtain the powder suitable for use in additive technologies, SHS powder of titanium carbide was ground preliminarily and then subjected to additional treatment in mixture with Ti powder in the planetary ball mill. As a result, the powder mixture consists of equiaxial granules containing fine TiC particles uniformly distributed in the Ti matrix. Results of the studies of the microstructure of samples obtained by means of selective laser melting (SLM) and electron beam melting (EBM) provide evidence of the advantages of SLM technology over EBM.

The operating experience for anode materials used in the production of fluorine shows that not all plates that meet the requirements of Russian technical specifications TU 48-12-34-95 have the required service life; some of them are destroyed quite quickly during operation. In this regard, we have carried out the studies of coke plates (CP) of Russian manufacturers using differential thermal analysis (DTA), X-ray structural analysis (XRD), atomic emission spectroscopy (AES), scanning electron microscopy (SEM), various physical-mechanical and electrical methods. The technical characteristics of the coke plates of two different trademarks: Doncarb produced by Doncarb Graphite LLC (Chelyabinsk) and VCC produced by the Volzhsky Chemical Complex LLC (Volzhsky) were determined: porosity, ash content, density, compressive strength, electrical resistivity. Technical characteristics described above fully meet the requirements of the Russian TU. It was shown that the content of impurities in Doncarb plates is 0.50 wt. %, while that in VCC plates is 0.33 wt. %. The porosity of the coke plate materials was carried out. In general, Doncarb samples are characterized by the presence of pores 0.6 to 12 μm in size, while the presence of larger pores (more than 117 μm) is characteristic of VCC samples. The presence of the turbostratic structure of carbon with the parameters d ₀₀₂ = 0.347-0.345 nm was established for the coke plates of both trademarks. Classification of coke plates with respect to their thermal stability was carried out on the basis of the data obtained by means of differential thermal analysis. The use of the obtained data as a supplement to the parameters included in TU 48-12-34-95 allows one to improve the evaluation of the quality of coke plates and to predict their lifetime reliably.

For the purpose of analytical application of thiopyrine in the analysis of the natural samples - the solid components of snow and the filtrate of surface river water, an equimolar melt of thiopyrinium salicylate with the melting point 145 °C was obtained, and its physicochemical properties were studied. The melt was used to extract the sorbed inorganic forms of copper, cadmium, lead, and zinc from the solid particles of snow cores sampled at the territory of Barnaul. The resulting extracts and acid mineralizates were analyzed by means of flame atomic absorption spectrometry. Analysis of the concentrations of chalcophilic metals under investigation allowed us to determine the total content of the sorbed forms and the mass concentration of inorganic forms of copper, cadmium, lead, and zinc in the solid particles from snow at the stage of sample preparation. The variation ranges for the mass concentrations of the inorganic forms were 50-94 % for copper, 58-95 % for cadmium, 68-89 % for lead, 74-89 % for zinc. The mass concentrations of organic forms were calculated from the difference between the amounts of Cu, Cd, Pb, Zn in the acid mineralizate and in the extract. The filtrates of river water were preserved with hydrochloric acid and studied separately with the help of layering in situ in the system of water (≥ 0.01М HCl) - thiopyrinium salicylate - modifier to form two liquid phases. The lower and upper phases were analyzed for the concentrations of Cu, Cd, Pb, Zn by means of stripping voltammetry. The degree of extraction of the ionic forms of copper (II), cadmium (II), lead (II) and zinc (II) from the samples of river water filtrate after single extraction was (92 ± 2), (90 ± 3), (94 ± 2), (97 ±1) %, respectively.

Data on the yield and composition of liquid products formed in the process of semi-coking of coals of the middle stages of metamorphism were obtained using a complex of analytical methods. It was demonstrated that the yield of semi-coking resins decreases with an increase in the genetic maturity of coal, but the aromaticity of liquid products increases, as indicated by a decrease in the H/C atomic ratio, as well as the presence of high-molecular-weight hydrocarbons in the form of asphaltenes and resinous substances. It was revealed by means of chromatography-mass spectrometry that during low-temperature pyrolysis, liquid products are formed, which are represented by a complex mixture of saturated and aromatic hydrocarbons. In all the resins, normal and branched n -alkanes and n -alkenes are identified. The aromatic hydrocarbons of the studied resins contain one to five benzene rings per molecule. Different amounts of these components in the composition of liquid products are due to differences in the chemical structure of the organic mass of coal samples studied. The obtained results expand the understanding of the composition of liquid products formed from the organic mass of coal during its low-temperature heat treatment in the semi-coking mode and open the ways to improve the environmental safety of basic technologies taking into account the number, individual composition and toxicity indicators of all the products formed.

A thermogravimetric study of the inertinite fractions of coal from different stages of metamorphism was carried out in inert and oxidizing environments. It was shown that with an increase in the degree of metamorphism of inertinite fractions during their pyrolysis in an inert environment within temperature range 360-900 °C, the temperature of the onset of mass loss increases, the rate of the main period of resin and gas release decreases, and the maximum thermochemical decomposition of coal in the DTG curve shifts to higher temperatures. It was established that in the series of metamorphism of the studied inertinite samples, their reactivity with respect to oxygen decreases, which is evidenced by an increase in the temperatures of the stages of the oxidation process: the ignition temperature of coal particles ( T₁), the temperature at which the maximum oxidation rate ( T_max) is reached, and the final temperature at which burnout of the coke residue occurs ( T₂). An increase in the values of these parameters is associated with an increase in the aromaticity index f_a of the organic mass of the samples and a reduced yield of volatile substances.

The data of the group and component composition of the ethanol extract of brown coal from the Tulgan deposit of brown coal in the South Ural basin are presented. It is shown by means of liquid chromatography, 13C NMR (CPMAS) spectroscopy, FT-IR spectroscopy, gas chromatography-mass spectrometry (GCMSD) that the extract contains: saturated and unsaturated hydrocarbons, alcohols, aromatic compounds, carboxylic acids and phenols. The following biologically active substances have been identified: 1-docosene; gamma-tocopherol; octadecanoic acid; ferruginol; eicosane; sugiol; beta-amyrin, concentrated mainly in the nonsaponifying fraction of the ethanol extract

The features of structural transformations of peat humic acids in the course of mechanical activation with iron oxyhydroxides and the changes in their surface-active and adsorption properties are revealed. It is shown that the maximum biological activity of the aqueous solutions of sodium humates is manifested when the concentration of the active substance of humic acids is below the critical concentration of micelle formation.

The chemistry of heterocyclic compounds has become one of the most dynamically developing fields of organic chemistry in recent decades. The role the heterocyclic compounds play in different areas of science and technology (chemistry, medicine, biology, electronics, etc.) can hardly be overestimated. In this regard, the development of new synthetic methods for functional derivatives of various heterocyclic compounds still holds relevance. Pharmaceuticals such as Trazodone, Nefazodone, Aprepitant, Itraconasole and others, which comprise the 1,2,4-triazol-5-one moiety, are widely used in modern medicine and pharmacy. The synthesis and characterization of the compounds of this series are of theoretical and practical interest. The design of novel drugs is based both on the directed synthesis of new drugs and on the screening of bioactive compounds derived by modifying the known drug molecules. Here we report two methods that give access to 3-nitro-1,2,4-triazol-5-one (NTO) alkyl derivatives, which is not possible via other common approaches. The success of our methods is due to the use of preparatively obtainable starting substrates and to the positional selectivity of all the reactions along a specified nitrogen atom. The strategy devised herein contributes to the progress in the theory of reactivity of ambident heterocycles and allows for selective synthesis of never-before-seen 1-substituted derivatives of NTO. The virtual screening of N-functionalized derivatives of 3-nitro-1,2,4-triazole and 3-nitro-1,2,4-triazole-5-one, which were obtained by the nucleophilic substitution of the nitro group, saponification and nitration, has shown their high biological activity in the most demanded areas of medicine - disease treatment, prevention and rehabilitation: cardiovascular diseases; diseases of the nervous system (neuromediators, neuroprotectors); anticancer drugs (cancer growth blockers). Therefore, such compounds arouse elevated interest among researchers in Russia and overseas.

For a long time, the inhabitants of the middle latitudes of the Earth mark annually recurring natural anomalies: at the end of May and beginning of June - a two-week return of cold weather, while at the end of September and beginning of October heat returns for the same couple of weeks. In time, these phenomena coincide with the beginning and end of photosynthesis in the respective regions. Although on average the plants on the planet spend only about 1% of solar energy for biosynthesis, we tried to prove that from the point of view of biophysics, these are strictly interrelated natural phenomena, and the beginning and end of plant biosynthesis can lead to a jump in air temperature in the surface layer by 5-10 degrees.