Home – Home – Jornals – Chemistry for Sustainable Development 2015 number 2

Separation of low-caking coal of KS technological grade into fractions with different densities was carried out. Their composition and chemical-technological properties were studied. It was established that the most aromatic fusainized components of coal are concentrated in coal fractions with the density higher than 1.40 g/cm³. The maximal content of vitrinite gelified substances is characteristic of coal fractions with the density lower than 1.30 g/cm³.

Analysis of the qualitative and quantitative composition of 13 representatives of polycyclic aromatic hydrocarbons (PAH) in the samples of coal from the Pikhtovskiy area of the Kedrovsko-Krokhalevskoye black coal deposit in the Kuznetsk Basin was carried out. Extraction of PAH from coal was performed using organic solvents (hexane, toluene, dichloromethane) in an ultrasonic field; quantitative determination was carried out by means of high performance liquid chromatography. It was demonstrated that the most efficient extracting agents are dichloromethane and toluene. Benzo(a)pyrene was detected in coal samples. Its content varies from 0.004 to 0.042 mg/kg; maximal concentrations were determined for phenanthrene - up to 0.535 mg/kg.

Coal from the Usinsk deposit of the Pechora coal basin was studied by means of IR spectroscopy and XPA. The structural parameters of coal samples were determined; their methane-bearing capacity was estimated with the help of the volumetric method in order to predict methane content of coal beds. The dependence of the amount of methane sorbed by coal on the thermodynamic conditions of tests was demonstrated.

Coal from the Pechora Basin of the Usinsk deposit was investigated using petrographic analysis. It was shown that coal samples are characterized by the close petrographic composition and are related to grade Zh (medium volatile coal) according to classification on the basis of genetic and technological parameters. On the basis of the data obtained, this kind of coal may be recommended as a raw material for the production of metallurgical coke.

The high heat value of black coal was measured in a calorimetric set-up. Analysis of the data showed that the coal combustion heat is directly dependent on carbon content. An increase in oxygen content causes a decrease in the calorific efficiency of raw coal. Confirmatory calculation of coal combustion heat according to the empirical formulas of Mendeleev, Dulong, Vondracek, Nivel and Given showed that the smallest deviations of calculated Q^daf values from experimental data on combustion heat may be obtained using Mendeleev's and Nivel's formulas.

Experiments on low-temperature alkylation of solid fossil fuels (SFF) of low coalification stage - brown coal, peat - were carried out using alcohols as alkylating agents. On the basis of the results of experiments involving analytical methods (IR, NMR spectroscopy, and gas chromatography-mass spectrometry) and the experiments with methanol labelled with ¹⁴С isotope, the distribution of the attached carbon from alcohol in soluble and insoluble products of brown coal alkylation was established. The efficiency of alkylation of brown coal and peat by alcohols under catalysis with proton acids is directly proportional to acid strength and increases in the sequence of alcohols: methanol < isopropanol < n-butanol < isobutanol < n-amyl alcohol. It was shown that esterification and interesterification of carboxylic and ester groups of the organic mass of SFF at low coalification stage in the presence of strong protonic acids proceed via A_AC2 and A_AL1 mechanisms (according to Ingold).

Effect of carbon nanomaterial on the thermal stability of photochemically treated polydimethylsiloxane materials doped with this carbon nanomaterial was studied. It was demonstrated that even the introduction of a small amount of carbon nanomaterial into high-molecular polydimethylsiloxane rubber SKT causes a substantial increase in the thermal stability of photochemically hardened polymer during thermolysis both in the inert atmosphere and in the air. This is assumed to be connected with its participation in suppression of destruction processes. The mechanisms of thermal and photochemical processes taking place in the polymer matrix are proposed.

Principal possibility to use polymeric phosphonate and dioxide of zirconium containing nanoparticles of palladium, silver and platinum as solid-phase nanoreactors for the catalytic oxidation of alkyl pyridines of coal-tar resin (β-picoline, γ-picoline, 2,6-lutidine) to pyridine carboxylic (nicotinic, isonicotinic and 2,6-pyridine carboxylic) acids - precursors of antituberculous preparations - was demonstrated.

Results of the synthesis and investigation of gold-carbon nanostructured composites are presented. The parameters of the porous structure of Au/C nanocomposites based on porous carbon materials (PCM) were determined. It was established that the pore size distribution functions calculated according to the nonlocal density functional theory for PCM-1 sample obtained by carbonization of naturally oxidized black coal, and composites based on it, are qualitatively similar, and the positions of major maxima coincide. It was shown that for the decoration of the surface of PCM-2 sample obtained by carbonization of individual aromatic compounds, the major maximum on pore size distribution functions shifts from 9 to 12 E, the maximum with pore size less than 4 E appears. The effect of specific surface of composites on the capacitance of electrodes made of them was studied.

Nickel hydroxide is formed on the surface of porous carbon matrix as a result of decomposition of nickel ammine at a temperature of 90 °C in an open-type reactor under intense mixing of the reaction mixture. Porous carbon material obtained by means of high temperature carbonization of hydroquinone - furfurol mixture was used as a matrix. The result is the formation of nanostructured composite filled with the crystallites of anhydrous Ni(OH)₂. Studies by means of X-ray diffraction and small-angle scattering of X-ray radiation showed that nickel hydroxide crystallites formed on the surface of carbon matrix have smaller size than the crystallites formed in solution without any matrix.

Nanosized powders of nickel-copper system were obtained by reduction of metal salts with hydrazine in strongly alkaline solutions. The particle size was studied using X-ray diffraction methods including small-angle scattering. The size of crystallites and nanoparticles, phase composition, lattice parameters of two fine metal phases formed in the system (solid solutions) were determined; oxidation products were studied. It was established that the size of bimetal nanoparticles within a broad range of compositions is substantially smaller in comparison with pure components (nickel and copper) obtained under the same conditions. It was shown that the ability of particles to get oxidized increases with a decrease in nickel content. The samples containing 90 % copper and obtained in the atmosphere of nitrogen are easily oxidized by atmospheric oxygen to CuO. In the case of preliminary etching with hydrochloric acid, these samples are oxidized to Cu₂O.

Nanoparticles of bimetal systems Co/Au and Ni/Au were synthesized in aqueous medium on the basis of reduction - electrochemical substitution of metals. The core/shell structure was confirmed by means of transmission electron microscopy, optical spectroscopy in the visible region, and small-angle X-ray scattering (SAS). Using the SAS curves, the mass functions of nonuniformity size distribution were calculated in the approximations of uniform spherical particles and core/shell structures. It was shown that the structure of particles is adequately described within the core/shell spherical model. On the basis of the analysis of particle size distribution profiles within this mode, the size and morphological parameters of Co/Au, Ni/Au particles were estimated.

A review of the works of the authors during the recent five years dealing with the investigation of the threshold of explosive decomposition of compounds based on TEN and ultrafine particles of different kinds depending on the content of inclusions in experimental samples under the action of the first laser harmonic is presented. Experiments with the samples containing Al 0.1 mass % under initiation by the second laser harmonic were carried out. It was established that explosion is initiated as a result of light absorption by inclusions with heating to high temperature but not as a result of optical breakdown. Experiments with different Al/Al₂O₃ ratios in separate particle were carried out. They demonstrated domination of light absorption processes. Comparative characteristics of the shock sensitivity of pure TEN and the samples of TEN with different concentrations of ultrafine Al particles were studied.

Polymer matrix, filler and composites based on low-density polyethylene and flue ash microspheres were studied using IR spectroscopy, DSC and TG, as well as the data on combustion heat. It was demonstrated that the introduction of microspheres into the polyethylene matrix leads to the change of structure as a result of an increase in the degree of polymer crystallinity, and to the formation of new chemical bonds, decrease in melting point and heat of combustion of the composites, an increase in the temperature of the start of intense thermal destruction.

Outlooks for the use of natural material — iron-manganese concretions (IMC) from the Gulf of Finland — as adsorbent for SO₂ are considered. The initial material in the form of pellets and powder was studied by means of X-ray spectral fluorescence method, by means of XPA, BET, TGA, SEM, determination of mechanical strength. The dependences of the physicochemical parameters of the material on thermal treatment within the range 100–1000 °C were established. IMC samples were tested in SO₂ sorption process. It was established that the sorption capacity of IMC samples with respect to SO₂ increases with an increase in adsorbent humidity. The promising character of the use of IMC samples with humidity above 40 % in gas purification from sulphur dioxide was demonstrated.

Methods of granulation of natural iron-manganese concretions (IMC) for obtaining adsorbents of gas purification from sulphur dioxide were developed. Granulated samples containing 80 to 100 % IMC and binders of different chemical nature were studied by means of the thermal desorption of Ar, low temperature adsorption of N₂, mercury porosimetry, TGA, SEM, determination of mechanical strength. Dependences of the physicochemical parameters of samples on chemical composition and thermal treatment within the range 100–400 °C were established. Granulated samples were tested in SO₂ sorption. It was established that the sorption capacity of samples with respect to SO₂ increases with an increase in adsorbent humidity. The optimal compositions of adsorbents, conditions of their thermal treatment are determined; recommendations for the use of the developed adsorbents in the processes of gas purification from sulphur dioxide are presented.

The structural characteristics of mainly mesoporous carbon materials synthesized through alkaline carbonization of hydroquinone-furfurol and phenol-furfurol mixtures were studied using a set of physicochemical methods (X-ray phase analysis, Raman spectroscopy, TEM and SEM, low temperature nitrogen adsorption). It was shown that the structural fragments of synthesized materials are composed of randomly oriented graphene planes and their layered aggregates. The average size of crystal-ordered regions is 12–15 Е.