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The issues of climate warming and permafrost thawing are considered. A procedure for assessing the Arctic landscapes thawing based on the calculation of the normalized differential snow index (NDSI) is proposed. The factual material over the data of the global permafrost monitoring network is presented. Monitoring studies have shown that according to the results of NDSI calculation, abnormally early snowmelt was detected in 5 cases out of 23 years of observation at the Urengoy meteorological station and in 4 cases out of 23 years at the Tarko-Sale meteorological station. The absence of snow was observed during the indicated period in 13 cases at the technogenic sites of the Urengoy field, and in 8 cases at the Tarko-Sale field. With early snowmelt, the snow index NDSI decreases, and the depth of the seasonally thawed layer increases at the sites of the Urengoy field. The NDSI index can be used directly in assessing the duration of snow cover and early snowmelt, and indirectly in studying the depth of seasonally thawed layer. The results obtained are important for predictive estimates of the rate and extent of thawing and permafrost deformation, and for the prevention of emergency situations in the oil and gas complex.

To enhance oil recovery and intensify the development of fields with hard-to-recover reserves, including the deposits of high-viscosity oils, acid oil-displacing compositions with prolonged action have been developed on the principles of green chemistry using the method of deep eutectic solvents (DES). These compositions are based on surfactants and an adduct of inorganic acid, polyol and carbamide. As a result of experimental studies of acid-base equilibria in three-component systems with donor-acceptor interactions “boric acid - carbamide - polyol (glycerol, pentaerythritol)”, which are DES, the optimal compositions and concentration ranges of the components in acid compositions were determined. The results of laboratory studies and pilot tests of enhanced oil recovery technology with the use of acid compositions are presented. The compositions are compatible with mineralized formation waters, have a low freezing point ((-20)-(-50) °С) or a solid commodity form, low interfacial tension at the boundary with oil, are applicable in a wide temperature range (from 10 to 200 °C), provide effective oil displacement and prolonged impact on the formation. The acid GBA composition showed high efficiency under field conditions during pilot work in the experimental areas of the Permian-Carboniferous deposit of high-viscosity oil of the Usinsk oil field, developed under natural conditions and under thermal steam exposure, and was recommended for industrial use. The technology is environmentally friendly and technologically efficient. The industrial use of technologies for enhanced oil recovery and intensification of oil production is promising, which will make it possible to extend the profitable operation of fields at a late stage of development, to involve the fields with hard-to-recover oil reserves into development, in particular the deposits of high-viscosity oils, in a wide range of climatic conditions, including the northern regions and the Arctic.

The results of a comparative gas chromatographic - mass spectrometric (GC-MS) analysis of the composition of saturated and aromatic hydrocarbons, as well as heteroorganic compounds in petroleum oils isolated from a number of crude oils and natural bitumens, before and after selective chemical cleavage (chemolysis) of C-S and C-O bonds of sulphide and ether/ester bridges, respectively, are presented. The revealed difference in the structural-group and molecular composition of some types of compounds before and after chemolysis indicates that alkanes, alkyltrimethylbenzenes, naphthalenes, phenanthrenes, tetra- and pentacyclic aromatic hydrocarbons, and dibenzothiophenes are present in oils not only as molecular entities, but, partially, as structural fragments linked via sulphide and ether/ester bridges with other fragments in complex high-molecular entities. Ester-bound high-molecular С₂₀-С₃₀ homologues predominate among the bound alkanes. The proportion of C₁₃-C₁₆ homologues among alkyltrimethylbenzenes decreases after chemolysis. Chemolysis is accompanied by an increase in the proportion of С₃-С₄ naphthalenes in petroleum oils. The ratio of homologues among phenanthrenes changes after chemolysis: as a rule, the unsubstituted compound predominates over homologues. The ratio of fluoranthene and pyrene to benzanthracene and chrysene increases among tetracyclic aromatic hydrocarbons. The main trend in the changes in the composition of dibenzothiophenes after chemolysis is a sharp decrease in the proportion of unsubstituted homologue.

New methods of zeolite HZSM-5 modification with bismuth compounds are proposed. The choice of bismuth as a modifying agent is due to the systematisation and generalisation of the available literature data and experimental results of studying the chemistry and synthesis of bismuth compounds of various compositions. Phases in the resulting bismuth-containing zeolite systems were identified by X-ray phase analysis, and the state of bismuth in chemical compounds was determined. The number and strength of acid sites in the original and modified samples were determined by the method of temperature-programmed desorption of ammonia. The catalytic activity of zeolites was studied in the process of hydrogen-free processing of straight-run gasoline fraction of oil into high-octane gasolines. The effect of modification methods and process temperature on the structural-group hydrocarbon composition, the yield of gaseous and liquid reaction products was studied, and the octane numbers of the resulting gasolines were determined. It is shown that over the bismuth-containing zeolite catalysts, in comparison with unmodified zeolite, the yield of the target product, high-octane gasoline containing a smaller amount of aromatic hydrocarbons, increases, which makes it more environmentally friendly. It has been established that the production of high-octane gasolines that meet modern requirements for motor fuels is possible over modified zeolites within a wider process temperature range. Based on the studies performed, Methods for modifying the HZSM-5 zeolite with bismuth are proposed on the basis of the studies performed. The proposed methods make it possible to improve the efficiency of the catalyst in the process of upgrading the straight-run gasoline fraction of oil.

The content and composition of organic compounds in the bottom sediments of rivers and in soils sampled at the Arctic territory affected by diesel fuel spill were studied by gas chromatography-mass spectrometry. The composition of diesel fuel was studied. It was found that the groups of compounds characteristic of diesel fuel - n -alkanes, polycyclic aromatic hydrocarbons, alkylbenzenes and trimethylalkylbenzenes, sesquiterpanes, steranes, and hopanes were found mainly in the samples taken downstream at a distance of 0.5-20 km from the pollution source. The highest concentration of identified compounds was detected in bottom sediments and soil sampled at a distance of 20 km from the spill, which is associated with the structural features of the riverbed and bank line. In the samples taken at more remote sites (40-90 km), the traces of diesel fuel components were found only in bottom sediments.

Citrate complexes of transition metals, namely cobalt and molybdenum, used as active components in the synthesis of catalytic systems supported on alumina for hydrotreatment of heavy oil fractions have been studied. Cobalt nitrate hexahydrate and polyoxomolybdate (molybdenum blue) obtained by mechanical activation of molybdenum disulphide (MoS₂) powder were used as initial compounds. Thermogravimetric analysis of the samples was carried out during their heating from 25 to 750°C at a rate of 15°C/min in air. A study by thermogravimetric analysis shows that the order in which the active components are introduced significantly affects the thermal stability of the sample. Despite the general similarity of the profiles, a shift of the temperature range of citrate complex decomposition is observed, depending on the order of active components introduction. Presumably, this may be due to the different degrees of Mo and Co availability for the formation of compounds with citrate ligands. It is shown that the most thermally stable system is the one in which the Co-containing component and citric acid are introduced first, and then the alcohol solution of molybdenum blue; the least stable system is the reverse one, in which the alcohol solution of molybdenum blue is introduced first, then citric acid and the Co-containing component are added.

The composition and distribution of organic compounds in the bottom sediments of the Tom River near the city of Yurga (the Kemerovo Region - Kuzbass) in 1995, 2005 and 2018 are determined by gas chromatography - mass spectrometry. The compounds included hydrocarbons ( n -alkanes, isoalkanes, naphthenes, alkylbenzenes, and polycyclic aromatic hydrocarbons), oxygen-containing compounds (carboxylic acids and their ethyl and propyl esters). The data on the group composition of the most dangerous pollutants, polycyclic aromatic hydrocarbons, are presented. The pattern of changes in the technogenic load on the river system made by the Kuzbass enterprises over different years has been established. The highest contribution into the pollution of the Tom basin was determined to be in 2005. This contribution is directly due to the industrial activities at the enterprises of Kuzbass.

The process of removing sulphur-containing compounds from the diesel fraction has been carried out and investigated. The systems based on coordinating polar solvents (DMF and DMSO) and metal salts (CuCl₂, CoCl₂, MnCl₂, Mn(TFA)₂, Cu(TFA)₂) were used as extractants. It has been established that the presence of metal salts in extraction systems increases the degree of removal of sulphur-containing compounds from the diesel fraction from 11 to 49 % and reduces the content of polycyclic aromatic hydrocarbons by 33 %. It is assumed that the addition of metal salts to the solvent enhances its acceptor properties, which is manifested in the enhancement of its extractability.

The results of rheokinetic measurements of changes in the fluidity of gel-forming compositions of various natures obtained by the methods of rotational and selection viscometry are presented. A technique for processing measurement results obtained by means of vibrational viscometry in measuring vessels of different sizes has been developed. Two directions of the interpretation of nonmonotonic rheokinetic dependences are considered.

Currently, the chemical nickel plating process is one of the most popular electroplating methods compared to others due to a number of advantages. However, the production process generates a significant amount of spent chemical nickel plating solutions, which poses a threat of environmental pollution. To solve this problem, the possibility of regenerating the spent solution of chemical nickel plating from one of the industrial enterprises of Udmurtia by the reagent method was studied. Sodium carbonate was chosen as the precipitant for nickel ions, the amount of which was determined from potentiometric titration curves; the most complete precipitation of nickel ions occurs at pH 10. It has been established by IR spectroscopy that nickel hydroxide salts are formed as a result of the interaction of the spent electrolyte with the precipitant. The results of thermogravimetric and differential thermal analysis of the precipitate showed three endothermic effects: at temperatures up to 100 °C, it corresponds to dehydration; at 280±10 °C - to the removal of a part of chemisorbed water and carbonates; at 420 °C - to the final removal of water. As a result of heat treatment of the hydroxocarbonate precipitate, a black fine powder of nickel (II) oxide is obtained, the IR spectrum of which has a set of bands characteristic of this compound. Two variants of the technological scheme for the regeneration of spent electrolytes for the preparation of initial working solutions for chemical nickel plating from nickel (II) hydroxocarbonate and nickel oxide are proposed. The quality of the obtained solutions was checked by applying a nickel coating on brass products. The thickness of the coating was measured by scanning electron microscopy. It has been established that the highest quality coating is obtained using an electrolyte prepared from nickel hydroxocarbonate.