Home – Home – Jornals – Chemistry for Sustainable Development 2017 number 5

The paper carried out distilling off hydrofluoric acid from model and process acid fluoride-sulphate solutions. Conditions for the most complete distilling off process of hydrofluoric acid from fluoride-sulphate solutions were determined and proposed. Fluorosulphonic acid is formed in large amounts, as demonstrated for model solutions containing hydrofluoric and sulphuric acids. Herewith, with increasing the concentration of acids, their interaction degree rises and fluorosulphonic acid is formed, as demonstrated. An increase in heating temperature of the mixture leads to a substantial increase in acidity due to HSO₃F content decrease. The larger the concentration of acids (especially, sulphuric) is, the higher heating temperatures are required to decompose HSO₃F, as established. The formation of fluorosulphonic acid may have a significant effect on the degree of distilling off hydrofluoric acid, as shown. The energetic and economic costs in processing of 1 m³ of process acid fluoride-sulphate solution are calculated with account of the initial concentration of HF of 78 g/L. Considering sulphuric acid regeneration and having excluded lime content for its neutralization, energy costs for processing of the same solution upon heating to 140 ℃ do not exceed 4500 RUB. The findings explain high solubility of lanthanide fluorides compared to their dissolution in monobasic acids, as noted in a series of papers. Our earlier observations of decreasing the concentration of fluorine determinable by potentiometric titration relatively to initially introduced one at pH correction by using sulphuric acid, unlike that with nitric or hydrochloric ones were also explained.

Distribution analysis of lithium, uranium, and arsenic in water of mineral lakes of Eastern Transbaikalia that are different by mineralization degree, macrocomponent composition, and water pH was performed. Lithium is mainly concentrated in more mineralized chloride lakes, and arsenic and uranium - in less saline, i.e. soda, as established. According to thermodynamic calculations, lithium is mainly present in lakes as Li⁺ ion; LiCO₃^- acts as second biggest in soda water bodies, and LiCl - in chloride. Uranium is mainly found as uranyl tricarbonate ([UO₂(CO₃)₃]^4-) and bicarbonate ([UO₂(CO₃)₂]^2-). Arsenic in oxidative environment of lakes is presented by hydroarsenate (HAsO₄^2-), and in reductive hydrosulphuric - dihydrogen arsenite (H₂AsO₃^-). Lithium does not form its own minerals in lakes. Reducing environment, in which it is precipitated as uranium hydroxide (U(OH)₄), may be a geochemical barrier for uranium. Sodium uranospinite (NaUO₂AsO₄) that may limit arsenic content in water too is likely to form under oxidative conditions. A single focus in the distribution of their contents in chloride lakes is observed for lithium and chlorine. Direct dependence of the concentrations of uranium and arsenic on the contents of hydrocarbonate and carbonate ions is typical of soda lakes. The lack of appropriate specialization in the catchment areas of most lakes with a wide variation of contents of lithium, uranium and arsenic in their water, and also the presence of direct dependencies on the contents of the main macrocomponents indicates the prevailing influence of geochemical environment in their accumulation, the formation of which is mainly determined by evaporative concentration of water and hydrolysis of aluminosilicate rocks. The prevalence of this or that process ensures the formation of a certain chemical type of lakes and the appropriate set of microelements.

The Ni/ZSM-5 samples were prepared by dry mechanical stirring of ZSM-5 zeolite with Ni nanopowder with 50 nm average particle size in terms of 0.5 mass %. Based on them, zeolite-containing catalysts with pseudoboehmite and hydrargillite containing 10, 20, 30 and 40 mass % of Al₂O₃ were obtained. Acid characteristics of the resulting samples were studied by the technique of temperature-programmed desorption of ammonia. The strength and concentration of catalyst acid sites were determined. Acidity decreased with increasing binder amount in zeolite, as established. Catalytic activity of nickel-containing samples with binder was studied during transformation of the straight-run gasoline fraction of oil. A part of pseudoboehmite used as binder to prepare catalysts could be replaced with its precursor, i.e . hydrargillite, as demonstrated. The yield of the liquid product, in the composition of which the aromatic hydrocarbon fraction decreased and the proportion of isoalkanes increased, rose during increasing binder content in the catalyst and carrying out transformation of the straight-run gasoline fraction of oil under high hydrogen pressure conditions.

Resistance of biocomposite fertilizers (BF) obtained via impregnation of porous substrates of bast and birch bark by an aqueous solution of K₂НРО₄ to washing-out of potassium was studied. The effect of drying temperature, acid treatment conditions, and initial potassium contents on its aqueous washing-out from the resulting fertilizers was found. Washing-out of potassium and phosphates from BF obtained under different conditions was compared. Fertilizers based on a substrate from the bast exceed those produced using birch bark by their resistance to washing-out of potassium by an average of 1.2 times, as demonstrated. Fertilizers production with maximum resistance to washing-out of potassium and phosphates requires that the amount of salt applied onto substrates should not exceed 29.5 mass %, as established. The resulting BF were characterized by the ability to slow isolation of the active components. After aqueous washing-out for 30 days, no less than 19.5 mass % of phosphates and potassium remained therein, which ensured the effect of prolonged action. The introduction of BF into peat soil in the amount of 5.0-15 mass % had little effect on its acidity. It was shown that BF based on substrates of bast and birch bark were not inferior to industrial granular fertilizer on their resistance to washing-out of phosphates, and on resistance to washing-out of potassium, on the contrary, surpassed it.

The paper presents the results of tar biochemical oxidation of Novokuybyshevsk Refinery with high contents of heteroelements in a model of the soil system. The microorganism population is restored to the initial level, and then increases in 20-30 times on the 4-5th day after pollution, as demonstrated. Enzyme activity of polluted soil increases in 1.5-1.8 times, which attests to an increase in oxygenase activity of microorganisms and consequently assimilation of different hydrocarbon compounds (HC). The formation and accumulation of incomplete HC oxidation products happens, as determined during biodegradation of tar components. The disposal of the studied oil product was 50 % of initial pollution on the 180th day of the experiment, as established. Native soil microflora is able to mineralization of almost all HC that are a part of the HC composition, as established by the GC/MS method. High molecular mass heteroatom tar components are also subjected to microbial degradation, as demonstrated. The structure of these species undergoes profound changes during degradation.

The paper studied the effect of texture characteristics gas diffusion electrodes (GDE) based on A 437-E acetylene black for electrosynthesis of H₂O₂ from O₂ in acid solution. Texture characteristics of the initial material (A 437-E) and its mixtures with hydrophobisator (fluoroplastic-4D (F-4D) were determined by the low temperature nitrogen adsorption (LTNA) method. Rate constants for hydrogen peroxide decomposition (K_chem) over these materials in acid solution were calculated. The dependence of electrochemical activity of GDE on the quantitative content of fluoroplastic-4D in the working layer was studied and process selectivity (γ) was determined. The effect of working layer texture of GDE has a substantial impact during developing highly developed surface 3-phase contact and removal efficiency of the target product from electrode pore volume. These conditions were met in electrodes with a low content of a hydrophobisator at comparatively high hydrophilic porosity. Minor microporosity of composites of working layers ensured low losses of the target product due to its heterogeneous decomposition and contributes to efficient removal from the electrode. The findings on accumulation kinetics of hydrogen peroxide during electrosynthesis from O₂ in acid solution at a current density of 150 mA/cm² in GDE with different F-4D contents were acquired. Acid solution of 2.43 М hydrogen peroxide with a current efficiency (CE) of 76 % and process selectivity of 0.69 was obtained in GDE using 5 mass % of F-4D for 5.5 h of preparative electrosynthesis.

Accumulation dynamics of biologically active substances (flavonols, catechins, tannins, pectin substances, saponins, and carotenoids) in the organs of aboveground parts of the plants Rheum altaicum Losinsk. growing in the experimental plot of the CSBG SB RAS (Novosibirsk, Russia) was studied. Their distribution character during vegetation period that is regrowth, budding, flowering and fruiting phases is demonstrated. The buds and flowers of plants may be a source of flavonols (7.40 and 5.89 %), catechins (0.91 and 2.01 %), tannins (32.37 and 27.83 %), and saponins (34.29 and 17.99 %, respectively), as established. Leaves in budding and flowering phases accumulate significant amounts of almost all groups of compounds, especially many carotenoids (160.05 and 191.81 mg/dL). Leaf petioles during these periods are a rich source of pectin substances (3.47 and 4.66 % of pectins, 7.22 and 9.20 % of protopectins), and saponins (24.06 and 22.3 %). Considering the findings, cultivated R. altaicum may be recommended as raw materials enriched with a complex of biologically active substances.

The paper is devoted to the development of an efficient scheme for analytical control of biogenic and oil hydrocarbons in bottom sediments using gas chromatography/mass spectrometry technique (GC/MS) without using toxic, expensive compounds and internal standards to acquire data of the depth of penetration of anthropogenic oil pollution and total contents of oil hydrocarbons (OHC). This testing scheme was performed for real objects with different environmental loads. Bottom sediment samples were taken in the Nizhnevartovsk District 30 km northeast from Nizhnevartovsk city. The study area is a series of lakes located in the territory of the Samotlor oil field in the West Siberian oil-and-gas province. The field is the biggest one in Russia. The deposit is the largest in Russia. Survey results of 28 oil-polluted water bodies allowed forming the scheme for carrying out analytical monitoring of hydrocarbons in bottom sediments, and also identifying a set of analytical parameters by which one can authenticate pollution of bottom sediments with oil and OHC, assess its level and composition characteristics, which in turn enables to receive specific data on the depth of penetration of technogenic oil pollution and the total content of hydrocarbons in bottom sediments.

The paper carried out approbation of dry fluoride technology for processing of zirconium-containing raw materials and treatment of the resulting fluorides from impurities under semi-industrial conditions. Research results of the process of fluorination of zircon and baddeleyite with elemental fluorine in devices of periodic and continuous action were given. The feasibility of efficient treatment of zirconium tetrafluoride from impurities via vacuum sublimation was demonstrated. Thus, high purity zirconium tetrafluoride was obtained. The design of a sublimation apparatus manufactured and tested under operating production conditions was proposed.

The paper carries out comparative analysis of products composition of ozonolytic destruction of sapropelite coal and oil shale kerogen from various fields of Russia. Sapropelite ozonation products could be used as fatty acid substitutes and other traditional flotation reagents based on oil during enrichment of metal ores and fossil fuels, as demonstrated. Thus, solid fossil fuels of sapropelite nature (properly sapropelite coal and non-sulphurous shale) that have a relatively regular structure of organic substances and oxidation products of uniform composition (mainly aliphatic mono- (C₉-C₂₅) and dicarboxylic (C₂-C₁₂) acids) could be considered as raw materials for obtaining analogues of flotation reagents based on oil that are used in the processes of enrichment of oxidized ores of non-ferrous metals, non-silicate salts of alkaline earth metals and ferrous metal carbonates. Products of ozonation of Barzas sapromixite (aliphatic, aromatic, and hydroaromatic acids) of sapropelite-humus nature may show shorthand and foaming properties in flotation of oxidized metallic ores and solid fossil fuels (coal and shale). Product composition of ozonation of Kashpirsk sulphur shale (aliphatic and sulphonic acids) allows obtaining sulpho-containing oxyhydryl flotation reagents based thereon. The latter can be used as collectors of non-sulphide minerals and emulsifiers. It is concluded that industrial development of oil shale Dmitrievsky and Barzas sapromixite deposits is promising. They are compactly located in the territory of the Kuznetsk Coal Basin with developed transport infrastructure and the presence of concentration plants in order to obtain chemicals and flotation reagents therefrom.

Modern medical science widely uses the following drugs that include 1,2,4-triazole structure: fluconazole, ribavirin, trazodone etc . In terms of fundamental research, the interest to 1,2,4-triazole derivatives is driven by great opportunities of structural design, which in turn opens up prospects to develop new generation functional materials with predetermined properties. Nucleophilic substitution may become one of the methods of functionalisation of 1,2,4-triazole ring at a carbon atom. 1-Methyl-5-nitro-3R-1,2,4-triazoles enter into a substitution reaction of the nitro group (S_N^ipso) with mono- and diatomic alcohols (tyrosol, phenylethanol, resorcin, hydroquinone) producing conjugates in 63.0-83.0 % yields, as demonstrated. Interaction process monitoring of initial substrates with O-nucleophiles and analysis of the resulting reaction products are carried out using ¹H NMR spectroscopy. The rate and direction of nucleophilic substitution reaction depend on both the structure of the initial substrate and the nature of the O-nucleophile, as established. The process is accompanied by competitive reactions of the substrate with hydroxide anion and triazolone formed in this reaction. Consequently, the same N-C triazolyltriazolone structure, i.e . 2,2'-dimethyl-2Н,2'Н-[3,4']bi([1,2,4]triazolyl)-3'-one is recorded in reaction products, regardless of the alcohol used. Products of nucleophilic substitution of the nitro group in 1-methyl-5-nitro-3R-1,2,4-triazoles by mono- and dibasic alcohols show activity (antiischemic, antihypertensive, and antiarrhythmic) that is currently of high interest in Russia and abroad for treatment and prevention of cardiovascular diseases, as demonstrated using PASS Online computer program. By using the method of holes, it is experimentally found that 1,3-dimethyl-5-(2-phenylethoxy)-1H-1,2,4-triazole displays antimicrobial activity against phytopathogenic fungi of the Fusarium oxysporum species.

Fenton reaction systems are widely used for oxidative activation of hydroperoxides in monooxygen oxidative functionalisation of organic compounds i.e. the introduction of an oxygen atom into the composition of organic substrates. The nature of intermediates that are direct oxidants until now remains a subject of hypotheses and discussions. Catalysts for Fenton oxidation are diverse, differing by the nature of elements (d,f,p elements) directly reacting with hydrogen peroxide species, its ligand surroundings, and the phase state. Literature explains the classic Fenton reaction in Fe²⁺/H₂O₂ systems generating either as a free hydroxyl radical, or iron (IV)-oxo cation; however, the both concepts were not verified. A common representation of hydrogen peroxide oxidation in Fe³⁺/H₂O₂ systems is not supported due to electrochemical criteria. The formation idea of the oxoiron (IV) species in Fe³⁺/H₂O₂ systems assumes the active participation of the ligand surroundings of Fe³⁺ ion as a second electron donor; therefore, it is limited by the nature of ligands, however, having obtained the widest spread in biochemistry when interpreting fermentative activity of Fe³⁺, in which protoporphyrin IX species are Fe³⁺ ion ligands. The key idea in copper Fenton chemistry that is hydrogen peroxide oxidation in Cu²⁺/H₂O₂ systems is even more unsupported from the standpoint of electrochemistry. Pathways for free hydroxyl radical generation are most often substantiated for systems based on other metals with variable valences. Interaction mechanisms of p elements with hydroperoxides are absolutely unclear. The concept of universal priorities of polarization and dissociation of hydroperoxides during their oxidative activation and decomposition by Fenton catalysts is proposed to the scientific community as a hypothesis. The initial transformation of Fe(II) dihydroperoxo species into a complex of Fe²⁺ ion with a molecule of oxywater (^-O-⁺OH₂)) that dissociates to form a complex of Fe²⁺ ion with the oxygen atom (iron (II)-oxene) in ¹D-singlet quantum state is assumed for the classic Fenton reaction. Afterwards, [Fe³⁺O^•-]²⁺ α-oxygen complex that is argumented as the major intermediate in Fe²⁺/H₂O₂ systems is formed resulting from the fast and inevitable intracomplex electron transfer. An opportunity for transformation of α-oxygen complex into intermediates for subsequent intermediates, such as oxoiron (IV) species, crypto-hydroxyl, and free hydroxyl radicals is demonstrated. A high probability for the invariability of oxidation degree of Fe³⁺ with the prevalence of [Fe³⁺O⁰(¹D)]³⁺ intermediate is substantiated for Fe³⁺/H₂O₂ systems, among other things, biochemical. The successful use of interpretation towards various catalysts, among other things, based on p elements is illustrated. Molecular oxygen (dioxygen) in the ¹∆_g singlet quantum state (¹O₂) that differs from the main (³Σ_g^-, ³O₂) triplet state is produced in Fenton degradation (disproportionation) of hydrogen peroxide. Singlet dioxygen is of preparative value in dioxygen alkene and alkadiene functionalisation processes, such as synthesis of hydroperoxides and cyclic peroxides. The life time of ¹O₂ generated in aqueous solutions of H₂O₂ is several microseconds. The ¹O₂→3O₂ quenching overcomes a ban for electron spin reversal via a yet unknown mechanism. The (¹O₂)₂ associate is formed from antipodes on the orbital moment, as supposed by us. Resulting from two simultaneous redox reactions, two ³O₂ species are formed. They are antipodes on spin moments of the unpaired electrons, the total spin of which is +1 and -1.