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A study was made of the change in the dynamic viscoelastic properties of silicone rubber with the addition of a small fraction (0.05; 0.10%) of single-walled carbon nanotubes. In the region of linear deformation, the elastic modulus and loss factor were measured. It has been established that the addition of nanotubes and the aging of materials lead to an increase in the elastic modulus, and the loss factor can either increase or decrease.

Problems are considered that describe the process of obtaining the residual angle of twist of a rod under creep conditions, taking into account elastic recovery after unloading. It is assumed that a constant linear angle of twist is set for the section being formed, i.e., the section is in conditions of pure torsion, without constraining the ends of the rod. It is believed that strains and stresses depend only on time and two spatial coordinates in the plane of the cross section of the rod. Direct and inverse problems of torsion of a rod with rectangular and angular cross sections in various kinematic creep regimes are considered. The speed of the angle of twist during the entire deformation process is set constant. A method of numerical calculation based on the finite element method is proposed, which makes it possible to obtain the stiffness characteristics of the section under torsion in the case of creep. It is shown that the minimum level of residual stresses is observed in the relaxation mode of deformation. For a rod with a cross-section of the angular type, modes are found in which stresses significantly decrease in the area of their concentration.

In the present study, an experimental approach is developed to study collisions of particles with a fixed air bubble. An air bubble with a diameter of 5.5 mm in deionized water is created, plastic particles (with diameters of 1.5, 2, and 2.5 mm) are released at different heights from the bubble surface, and their collisions with the bubble surface are studied. The results show that the particle size significantly affects the particle velocity and sliding time on the bubble surface. As the particle diameter increases, its sliding velocity on the bubble surface increases, and the particles are detached quickly from the bubble surface. The effects of the drag, capillary, pressure, weight, and buoyancy forces acting on the particles during the attachment-detachment on the bubble surface are also studied. The results show that the particle stays attached if the capillary force is dominant. The effects of the three-phase contact line on the capillary and pressure forces are also analyzed. A modified Bond number is proposed to check the attachment-detachment regimes.

Results of geochemical investigation of drainage waters discharging from the mining objects (dumps, quarries, tailings) of the Orlovskoe tantalum deposit (Transbaikal Territory) are presented. It is determined that the drainage waters from the dumps of overburden rocks and from blast holes are acid and weakly acid, and highly mineralized (TDS up to 4232 mg/L). With respect to the chemical composition, these waters are mainly of sulphate type, with anomalously high concentrations of aluminium, fluorine, chalco- and siderophilic elements. The waters of the tailing storage facility are neutral and weakly alkaline, with increased tungsten and arsenic concentrations. Thermodynamic calculations of the major forms of element migration in drainage waters show that simple cationic forms dominate for most metals, while the second prevailing forms are sulphate and fluoride complexes. The average concentrations of Mn, Al, Be, Zn, Fe, Li, Со, Ni, Cu, W, F^- and SO₄^2- are determined to be substantially higher than the maximum permissible concentrations for water objects for fishery, household, drinking and amenity water usage, which is connected both with the composition of the ores and host rocks of this deposit, and with technogenic activities.

In this study, the conditions for the precipitation of aluminium hydroxide from sodium aluminate solutions obtained from the alkaline solution of raw alunite ore by hydrogen peroxide, an eco-friendly reagent, are studied. Factors influencing the precipitation by H₂O₂ and aluminium hydroxide from diluted aluminate solutions (concentrations of hydrogen peroxide and alkali, volume ratios of hydrogen peroxide and aluminate solution, temperature, time, caustic modulus) are investigated and found under optimal conditions (initial concentration of hydrogen peroxide >15 %; temperature 20-40 °C, V_H2O2/V_sol = (5-20) : 20 mL, alkali concentration 42.33 g/L (according to Na₂O)) precipitation of ~95 % of aluminium in aluminate solution is achieved. The recovery of alkali (sodium hydroxide) after the precipitation of aluminium hydroxide by H₂O₂, its return to the leaching of alunite has been studied, and several difficulties have been eliminated in the precipitation of aluminium hydroxide by other methods. The characteristics of the obtained samples are confirmed by means of XRD, SEM/EDS analysis.

The problem of utilization of sludge from the storage facilities of the Baikal Pulp and Paper Mill (BPPM) for the purpose of improving the environmental situation in the Baikal region is considered. Geographical and seismic characteristics of the territory where this object of environmental danger is located are described. The factors threatening Lake Baikal are highlighted. Qualitative and quantitative characteristics of sludge-lignin contained in sludge storage facilities are presented. During the recent years, all the numerous attempts to utilize sludge-lignin invariably ended in failure. Transportation of waste to other temporary settling tanks located at a distance from Lake Baikal also would not solve the problem and can only worsen the current situation due to the large volume of accumulated waste and the permanent flow of rain and snowmelt water into the settling tanks. A retrospective review of the technical, technological and organizational measures taken by the administrative and engineering personnel of the BPPM and aimed at economically affordable and environmentally friendly disposal of sludge waste from sedimentation tanks was carried out. The analysis of patent, scientific and technical data bases made it possible to select a number of documents concerning the reactivity of lignins in the sulphate production of cellulose. The information is found that the dry sludge-lignin product of BPPM had been in demand by oil and gas exploration enterprises throughout Siberia for several years (1980-90s) as a cheap substitute for water-soluble cellulose esters, starch, xanthan resins and other components for washing liquids during the construction of deep oil and gas wells. Ways of utilization of the sludge-lignin component of the BPPM sedimentation tanks are proposed.

The effect of the mixtures of ethers and alcohols on the performance characteristics of motor petrol is investigated. The objects of investigation are industrially available domestic oxygenates: methyl tert -butyl ether (MTBE) and isobutyl alcohol (IBA). Investigation of the effect of the ratio of these oxygenates in the two-component mixture on the change in antiknock activity of petrol revealed a synergistic effect in the octane number within the range of the concentrations of MTBE (20 to 80 wt. %) and IBA (80 to 20 wt. %). Involvement of this two-component mixture in petrol provides an increase in the octane number. The optimal ratio of oxygenates is determined (MTBE/IBA = 50 : 50 wt. %), which provides, along with the manifestation of the synergistic effect in octane number (an increase by 7.9 units), a more uniform distribution of octane numbers over fractions and stability of performance characteristics during transportation and storage of commercial fuel. Resulting from the discovered synergism of oxygenates MTBE and IBA, a new additive to motor petrol is developed. In order to enhance and expand the range of action of the new additive based on the two-component mixture of MTBE and IBA, a formulation involving monomethylaniline (MMA) and anti-corrosion additive DCI-11 is developed. At the same time, the amount of MMA involved in motor petrol compounding did not exceed the sensitivity of the method. In comparison with the additive based on the two-component mixture, the use of the additive with an extended range of action made it possible to enhance the anti-knock characteristics (at the level of 1 octane unit, depending on the ratio) and anticorrosive properties (degree of corrosion 0 points) of petrol.

The effect of natural surfactants (SA) on the efficiency of the polymer additive against the formation of deposits in high-paraffin oil with increased content of resin-asphaltene components is investigated. It is demonstrated that the addition of the polymer to oil, either individually or with natural SA, causes a decrease in the amount of the formed deposits. It is determined that the maximal inhibiting ability is exhibited by the composition containing the polymer and 0.03 wt. % naphthenic acids (SA). Natural SA, either alone or together with the polymer, when added to oil, cause a decrease in the size of associates of paraffin hydrocarbons and their aggregates in the oily fraction of the oil deposits under investigation.

As an alternative to mercury release by cementation on metallic aluminum, for the purpose of improving the purity of commercial selenium, we investigated the processes of selective sorption of mercury ions from the technological solutions of selenous acid onto styrene-divinylbenzene Lewatit MP 68 resin. The isotherms of mercury ion sorption are obtained, the main quantitative parameters and limiting stages of the process are assessed. It is established that for a low degree of resin filling with the sorbate (with the equilibrium concentration of mercury ions in solution ≤0.4 mmol/dm³) and for the sorbent - sorbate type interaction, the distribution coefficient decreases initially, and then increases while the sorption ability increases and the structures of sorbate - sorbate type are formed. The degree of mercury extraction from solution (β) is inversely proportional to the equilibrium concentration of mercury ions in the solution ( С_eq) and is described by the linear equation: β = -133.5 С_eq + 99.81. Experimental data processing shows the simultaneous occurrence of the stages of external (film) and internal (gel) diffusion, which is evidence in favour of mixed diffusion sorption mode. The rate constants of external diffusion are approximately three times larger than the rate constants of internal diffusion. It is shown that the kinetic equations of pseudo-first and pseudo-second order models provide satisfactory description of experimental data, and that the difference between determination coefficients is not large ( R_i² > 0.98). The values of thermodynamic functions of mercury sorption within the temperature range 298-333 K were determined: -Δ G = 2.35-2.99 kJ/mol, Δ H = 3.1 kJ/mol, Δ S = 18 J/(mol•K). The practical significance of the revealed sorption parameter (dynamic exchange capacity of Lewatit MP resin is 68-269 g/dm³, specific volume of solution for resin saturation in the dynamic mode is 3800, element content in saturated resin is, %: Hg ~26.0, Se <1.0) is due to their involvement in designing the industrial installation.

A new method of purification of rough sphene concentrate from phosphorus impurities has been developed, based on its treatment with low-concentrated solutions of orthophosphoric or sulphuric acids in the presence of sulphocationite. It is shown that this method provides effective purification of sphene concentrate and makes it possible to increase the efficiency of the technology through significant reduction of the consumption of acids, elimination of the formation of liquid waste, and due to the possibility of using aluminium, which is formed during the decomposition of nepheline contained in the initial concentrate.