Search

The influence of the concentration and composition of humic acids (HAs) on the biodegradation of petroleum hydrocarbons was investigated. The HAs were obtained from oxidized brown coal by alkaline extraction upon the mechanical treatment of coal in the presence of 3 and 8 wt % NaOH (HA1 and HA2, respectively). It was found that solid-phase alkaline hydrolysis in the presence of 8 wt % NaOH with the subsequent separation of HA2 with water led to an increase in the degree of aromaticity and the number of phenolic groups. The soil microflora stimulated by HA1 and HA2 had an increased destructive oil-oxidizing activity. A decrease in the concentration of phenanthrene in solution due to the formation of a complex upon interaction with humic acids was established by spectrophotometry.

The effect of complex physicochemical treatment combining low-frequency acoustic action and the use of depressor additives on the composition and viscosity properties of oil sludge was studied. After the complex action, the viscosity of the treated sediments additionally decreased by a factor of 1.5–2, and the thixotropic recovery of properties increased to 72 h. The minimum values of the viscosity of the mixtures of oil sludge with oil correspond to a maximum decrease in the concentration of benzene and alcohol–benzene resin components and an increase in the amount of the oil fraction.

The mechanical treatment (MT) of brown coals in the presence of a complex of oxidizing alkaline reagents and mineral salts increased the yield of water-soluble humic substances (HSs) by 20–30%. The composition of coals and reagents in the MT affected the concentration of acidic functional groups in humic acids. Ion-exchange processes during the MT of coals with mineral salts were accompanied by an increase in the concentrations of macro and trace elements in the composition of HSs. A significant increase in the antioxidant activity of humic acids was found upon MT with ammonium phosphate and ammonium sulfate. Mineral elements in HSs exhibited physiological activity by influencing the development of wheat roots and seedlings.

Formation of stable water-in-oil emulsions in light and heavy crude oils was shown to involve the buildup of interfacial layer characterized by increased contents of the main emulsifiers, asphaltenes and resins. An increase in the proportion of asphaltenes in the interfacial layer, nearly 4-fold for the light oil and 1.3-fold for the heavy oil samples, was accompanied by changes in their elemental and structural-group compositions. The proportions of resins in the interfacial layers exceeded by 25–86% those in the original oils. IR-spectroscopic examination revealed increases in the concentration of carboxy and methylene groups in the asphaltenes and resins from the interfacial layer of the light oil and in the concentration of sulfoxide and carboxy groups from the interfacial layer of the heavy sulfurous oil. The dependence of the surface activity of resins and asphaltenes on pH of the aqueous phase was elucidated. Asphaltenes and resins exhibited decreases in interfacial tension (2.3–3.2-fold maximum) in the pH range 10–12 compared to pH range 4–6, which was due to neutralization of their constituent carboxy groups. Reduction of the interfacial tension in the acidic region was attributed to the presence of sulfoxide groups, possessing the properties of weak bases, in the emulsifiers.

Mire ecosystems in Western Siberia play a significant role in the environment and sustain ecological balance in the biosphere. The aim of the research was to study the chemical and biological processes of mire pedogenesis and the influence of this process on the formation of the composition of bog water and its migration to surface waters. The research was carried out in the southern taiga zone of Western Siberia in a small catchment of the Klyuch River within a catena of geochemically linked mire landscapes. The chemical and microbiological properties of the peat soils were studied in autonomous, transitional, and accumulative geomorphic positions; their influence on the formation of chemical composition of bog water was determined in each position. It was shown that a predominance of certain plant associations (oligotrophic sphagnum, cotton grass, or sedges) caused the accumulation of organic matter of significantly different chemical compositions. The biochemical activity could be traced throughout the peat profiles and affected significantly the chemical composition of bog water. Bog water had certain individual chemical properties in each landscape position. The factors affecting the migration of substances and the removal of chemical compounds beyond the studied profile were determined. The overall removal of macroelements with runoff flows during the growing season amounted up to 4843 kg/km2 for Ca2+, 51.7 kg/km2 for total Fe, 1419.0 kg/km2 for $${\text{SO}}_{4}^{{2 - }},$$ 2.253 × 10–3 kg/km2 for Pb, 10.037 × 10–3 kg/km2 for Cu, 317.29 × 10–3 kg/km2 for Mn, 41.191 × 10–3 kg/km2 for Zn, 8.151 × 10–3 kg/km2 for Ni, and 29.651 × 10–3 kg/km2 for Ti. The removal of organic matter reached 583.2 kg C/km2. The influence of bog water (especially, its organic components) on the water composition in the Klyuch River was clearly shown. Our data on the chemical composition of bog water in the system of geochemically linked more landscapes and on the bog water migration from the boggy catchment can be used to forecast the geochemical situation in the surface waters of boggy territories.

The elemental and structural-group compositions and paramagnetic properties of the humic acids of peat occurring at different depths of peat deposits of various geneses have been investigated. With decreasing the depth of peat occurrence, the extracted humic acids were characterized by a decrease in the Н/С ratio and the amount of carboxyl and methylene groups and an increase in the signal intensity of organic paramagnetic centers (PMCs), which indicated an increase in the aromatic conjugation structure. The change in the amount of PMCs in the humic acids of peat along the depth of a deposit was directly dependent on the Fe3+ content.

The influence of the formation temperature of emulsions and their water cut on their rheological properties and the amount and composition of deposits precipitated from them has been studied. It has been shown that at a formation temperature of 40°C, the emulsion is characterized by maximum values of viscosity, activation energy of viscous flow, and amount of the deposit precipitated and by higher temperatures of phase transitions due to crystallization of paraffin hydrocarbons.

The formation of organic deposits in model petroleum-containing systems of various compositions has been studied. Introduction of asphaltene–resin substances into a model paraffin system reduces the amount of precipitated wax deposit to 40 wt %; significantly changes the ratio of liquid and solid hydrocarbons in the n-alkane composition of the deposits, shifting the distribution maximum towards a lower molecular weight; and substantially reduces the mechanical strength. In the model paraffin system in the presence of resins and asphaltenes, which contain a greater amount of condensed aromatic structures and a smaller amount of paraffin structures, a precipitate is formed with an increased proportion of the liquid phase. The deposits are characterized by lower strength of the crystal lattice and, hence, a decreased value of ultimate shear stress.

The effect the mechanochemical modification of humic acids has on their surface-active and acid–base properties is studied. The dependence of the surface activity of humic acids on structural changes, concentration, and the pH of the medium are determined. It is shown that in an alkaline medium, associates of humic acids are characterized by the minimum average particle radius, an increased degree of dissociation of acidic groups, and enhanced surface activity at the gas–liquid interface. A neutral or acidic medium facilitates aggregation and an increase in the size of macromolecules of humic acids.

The motion of electrons in giant fullerenes due to geometrical potential is investigated in the one-electron approximation. It is shown that because of flexural excitation of curvature, the geometrical potential induces a normal surface force, which affects the mechanism of small-amplitude surface oscillations of giant fullerenes. The inclusion of the geometrical potential in giant fullerenes reduces or completely compensates the effect of free transverse (radial) oscillations of the spherical layer.

The generalization of literature data and the results of our scientific research over many years has led to the conclusion that physicochemical effects on natural organic materials can be key in the manifestation of their biological activity to reduce the toxicity of pollutants in the environment and improve plant growth. The bioactive properties of humic substances were studied using luminol-dependent luminescence and bioluminescence. It was shown that humic substances have the highest physiological activity for germination of wheat seeds at the concentration of 0.01 g/l. Possible to reduce the concentration of humic substances by the mechanoactivation or the UV-irradiation. The results of this work are promising for the development of approaches for the biological recultivation of polluted or depleted lands using humic preparations isolated from peat. The evaluation of morpho-physiological responses of wheat and the enzyme activity of a soil in presence of an irradiated humic acids were discussed.

The eigenvalues and eigenfunctions for clusters with planar, cylindrical, and spherical geometry with arbitrary potential energy profiles were calculated by means of an implemented algorithm. The results of numerical and analytical solutions for clusters of various geometry were compared. The proposed algorithm for determination of cluster eigenvalues and eigenfunctions shows a power law rate of convergence of the solution towards the target eigenfunction coinciding with the rate of convergence in the modified Wielandt method. This algorithm was used to calculate the geometrical potential of giant fullerene as a function of radius for the state with l = 0. The numerical results are in good agreement with the theoretical results.

The analysis of the mechanochemical transformations of humic acids (HAs) in caustobioliths of different genesis (peat, brown coal, and oxidized coal) was carried out. It was found that the greatest changes in the peripheral carbohydrate fragments and the aromatic framework of a HA macromolecule occurred upon the mechanical activation of less transformed peats. The mechanochemical solid-phase alkaline hydrolysis of HAs was performed. Changes in the composition of HAs in the process of mechanical activation, which consist in an increase in the number of acid functional groups and in the degree of oxidation of aromatic and aliphatic fragments and in a decrease in the aromaticity of macromolecules, were detected.

The results of the pyrolytic analysis of products of the organic matter of Sphagnum fuscum, fuscum peat, and humic acids separated from peat with the use of pyrolysis–chromatography–mass spectrometry in the Rock-Eval version are presented. It was shown that Sphagnum fuscum and peat differed only slightly in the degrees of chemical transformation. Benzene, phenol, and their alkyl-substituted homologues predominated in the thermal desorption products of humic acids upon pyrolysis to 400°C. Acetic acid, monohydric phenols, syringol, and guaiacol, which are the basic compounds in the high-temperature fraction, were formed on the pyrolysis humic acids to 700°C from the carbohydrate, phenylpropionic, and guaiacylpropane structural fragments.

The structural properties of humic and himatomelanic acids are studied by means of 1Н NMR spectroscopy and differential thermal analysis after mechanochemical modification of peat. The relationship between the structural modification of humic and himatomelanic acids and their surfactant properties in aqueous solutions is established. It is shown that the critical micelle concentration of transformed himatomelanic acids is halved in comparison to the initial sample, while the adsorption equilibrium constant grows by 9 times.

The rheological properties of water-oil emulsions formed at different temperatures are investigated. It is shown that viscosity, and pour point of water-oil emulsions depend on the conditions of their formation and the degree of water cut. An increase in the emulsion formation temperature from 10 to 40°C leads to an increase in the mean diameter of water droplets. The water content has more influence on the rheological properties of emulsions formed at 10 and 20°C, than the conditions for their formation The pour point of emulsions formed at 10 and 20°C does not change, and the values of dynamic viscosity increase with increasing water content by almost 2 times. The formation temperature of 40 and 60°C has a significant effect on the rheological properties of emulsions. Emulsions formed at 40°C are characterized by maximum values of the pour point, mean diameters of water drops, and the viscosity. For emulsions formed at 60°C, the minimum values of the pour point, the mean diameters of water drops and viscosity are observed.

Aggregation of asphaltenes over time in the presence of dispersant S5A has been studied using photon correlation spectroscopy. The addition of the dispersant to toluene solutions of asphaltenes decreases the size of the aggregates, stabilizes their growth, and reduces the rate of aggregation for a considerably long time. The growth stabilization is achieved at the asphaltenes to dispersant ratio of 0.2–4.

Conditions for the solid-phase mechanochemical activation of coals, which make it possible to substantially increase the yield of water-soluble humic preparations enriched in humic acids and mineral elements, are given in this work. It was found that the humic preparations isolated from mechanically activated coals are characterized by an increase in the antioxidant activity and a change in the cationic and anionic composition. The concentration of acidic ionogenic groups in humic acids increased.

Effect of ultrasonic treatment on the molecular parameters of polymeric additives based on polyalkyl acrylate is investigated. The viscosity, temperature, and energy characteristics of high-wax crude oil and solutions of petroleum wax in decane and aviation fuel TS-1 in the presence of initial and ultrasonified additives are determined. Results obtained indicate that the pour point depression ability of the additives is not reduced after treatment in an ultrasonic field.

A composite additive for oil pipeline pumping has been tested as a viscosity modifier and crystallization modifier (depressant) in two crude oils and gas condensate of West Siberian deposits with the different content of resins and waxes. The additive represents a toluene solution of a cationic surfactant and an amphiphilic copolymer of alkyl acrylate C16-C20 with a salt of acrylic acid and higher amine. Pour points, rheological characteristics, phase transition temperatures, energies of the destruction of supramolecular structures were determined for investigated oils with different concentrations of the additive. The comparison of the efficiency was made for the composite additive, a commercial depressant and surfactant-free additive.

The composition and viscosity–temperature properties of waxy, high-resin crude oil treated in ultrasonic field have been studied by gas chromatography–mass spectrometry, IR and 1H NMR spectroscopy, and rotational viscometry techniques. It has been shown that the ultrasonic treatment leads to an increase in the proportion of lower n-alkanes in the oil fraction of the treated crude and a reduction in viscosity and the pour point of the crude oil.

The deposit formation process in water/oil emulsions based on waxy high-resin oils with different amounts of the aqueous phase has been studied. It has been shown that the deposition rate greatly increases with an increase in the relative amount of the aqueous phase. Relationships of the component composition of paraffin hydrocarbons and the structural group composition of asphaltenes in asphaltene–resin–wax deposits with the water content of the emulsions have been revealed.

Interaction of humic acids with polyaromatic hydrocarbons (PAH) (naphthalene and anthracene) and triazole series fungicides (cyproconazole (CC) and tebuconazole (TC)) is investigated by the method of fluorescence quenching depending on the concentration of substances in solutions and their structural features. Humic acids were modified by mechanochemical activation in a planetary mill. The complex character of intermolecular interactions between PAH and fungicides with humic acids, including donor-acceptor and hydrophobic binding, is established. Thermodynamically stable conformations of biocide molecules were estimated using ChemOffice CS Chem3D 8.0 by methods of molecular mechanics (MM2) and molecular dynamics. Biocide molecules with pH 7 are in energetically favorable position when the benzene and triazole rings are almost parallel to each other. After acidification of solutions to pH 4.5, the CC molecule retains the geometry for which donor-acceptor interactions are possible: the benzene ring in the molecule represents the electron donor, and triazole is the acceptor. In this case, the electron density in CC is redistributed easier, which is explained by a smaller number of carbon atoms between the triazole and benzene rings, unlike TC. As a result, the TC triazole ring is protonated to a greater degree, acquiring a positive charge, and enters into donoracceptor interactions with humic acid (HA) samples. The above-indicated bond types allow HA to participate actively in sorption processes and to provide their interaction with biocides and PAH and hence, to act as detoxifying agents for recultivation of the polluted environment.

Conditions were found for solid-phase mechanochemical activation of coals, allowing a significant increase in the yield of water-soluble humic preparations enriched in humic acids and mineral elements. The humic preparations are characterized by a decrease in the molecular mass and by changes in the ionic composition and surface activity. The physiological activity of the humic preparations was determined.

The mechanochemical solid-phase reactions of humic acid with Cu2+, Ni2+, and Cd2+ metal ions were studied. The analysis of the mineral composition of humic acids by atomic emission spectrometry showed an increase in the concentrations of Cu2+, Ni2+, and Cd2+ ions after mechanical treatment.

In this work, based on a comprehensive analysis of the optical absorption spectra obtained by spectrophotometry in the visible region, the change in the stability of asphaltenes isolated from wax deposits of emulsions with different water contents were studied. Asphaltenes of oil-water emulsion wax deposit with a small water content are characterized by maximum values of the light absorption coefficient. Asphaltenes which characterized by maximum values of the coefficient of light absorption and more capable of aggregation form wax deposit of 10 and 30 % of water-oil emulsions. A further increase in the water content in the emulsion to 50 and 70 % leads to the fact that the values of the light absorption coefficient are reduced, i.e. wax deposit form more stable asphaltenes. The least stable asphaltenes contain a highly aromatic polar fraction, are characterized by high molecular weights and precipitate from emulsions with a small water content and minimal average droplet sizes.

Effect of impact of acoustic conditions on the breakdown of a stable oil-water emulsion is studied. The emulsion contains 80, 10 and 10 wt% of a solution of petroleum paraffin in 6 wt% of kerosene, distilled water, and highly resinous oil, respectively. Samples are treated in an ultrasonic field for 1-15 min at a frequency of 22 kHz, intensities 2, 6, 18 W/cm2, and temperatures 0 and 20 °C. It is shown that under optimal conditions of treatment (temperature 20 °C, 10 min, field intensity 18 W/cm2) ultrasound causes the breakdown of the model emulsion. After demulsification, water, paraffins, and asphaltenes are concentrated in the lower layer. Ultrasonic treatment can be successfully used to treat watercut oils for transport.