Home – Home – Jornals – Chemistry for Sustainable Development 2019 number 5

The possibility of obtaining a polydisperse porous material from the birch bark bast with subsequent separation into an enterosorbent and a porous substrate is demonstrated. A technological scheme is developed for processing birch bark bast, which allows one to obtain polydisperse porous material with the yield of 43.5 %. It is proposed to use the fraction of the size less than 0.25 mm as an enterosorbent, and the fraction of 0.25-1.0 mm as a porous substrate to obtain biocomposite fertilizers. It was established that the enterosorbent from birch bast is not inferior in its properties to the industrial enterosorbent "Polyphepan" from hydrolytic lignin. It is shown that, on the basis of the porous substrate, it is possible to obtain a complex biocomposite fertilizer with a growth-promoting effect and increased resistance to the washing out of active components by water. Slow leaching of macro- and microelements from the fertilizer determines the effect of its prolonged action. Thus obtained fertilizer is superior in its resistance to leaching of phosphates and potassium to the industrial granular fertilizer brand "Kemira Universal-2". Taking into account the particle size, lignin content and swelling ability, the porous substrate can also be used as a structuring additive in the soil. To obtain porous materials from the birch bark bast for various purposes, the enlarged plant is proposed, which allows processing up to 12 kg of the raw material in one technological cycle.

Results of the field studies of the snow cover composition around dumps and a highway of the Gorlovka coal deposit are presented. The prevailing element in technogenic dust is carbon. The concentrations of almost all the elements in the dissolved and suspended parts of the snow cover exceed background values. The migration ability of the elements in snow samples collected near the dump and near the highway are similar. However, the distribution coefficients of the elements in snow samples from the highway region are lower, which is the evidence of their transfer in more mobile forms here. The influence of the Gorlovka anthracitic deposit on the surface layer of the atmosphere extends to more than 1000 m. At the same time, the highway along which the extracted coal is transported has a stronger influence on the state of the atmosphere than the dump for overburden and host rocks. The shielding effect of forests located along the road is shown.

A limited life span of endoprostheses in the absence of other complications is explained by the aseptic implant instability arising and developing as a result of insufficient osteointegration. The surface of implants made of the VT-6 alloy was treated to form calcium phosphate coatings including those containing germanium (0.4 and 2.5 mass %), for the purpose of carrying out a comparative analysis of the response of an organism. The surface of the resulting coatings was investigated by means of scanning electron microscopy. It was established that the introduction of germanium has a substantial effect on the surface morphology of the coatings. It was shown with the help of the light microscopy of histological sections that osteointegration processes are most intense with the group of implants containing germanium at a level of 2.5 mass % in the calcium phosphate coating.

One of the main requirements for tantalum oxide semiconductor capacitors is the reduction of the equivalent series resistance (EPS), the value of which is directly related to the electrical conductivity of the semiconductor manganese dioxide layer formed on the surface of the tantalum electrode. Analysis of the current state of the production of electrolytic capacitors in Russia showed that the industry survives a steady trend towards an increase in switching frequencies from 10 to 100 kHz and higher, necessitating a reduction in the EPS of the finished capacitor. At the same time, manufactured products do not have the necessary characteristics for operation at higher frequencies. Existing technology solutions do not provide the production of high-quality capacitors, since they are multistage, energy-intensive and require continuous improvement. This paper deals with the search for ways to improve the electrical characteristics of a manganese dioxide cathode coating on tantalum oxide semiconductor capacitors. A theoretical analysis of the literature was conducted in order to determine the probable causes of the increased equivalent series resistance of a capacitor. The properties of factory-made tantalum oxide semiconductor capacitors were investigated by means of X-ray phase and photomicroscopic analysis; their electrical parameters were determined. It was shown that an increase in the equivalent series resistance of capacitors is due to the presence of an impurity of high-resistance manganese oxide (III) in the composition of the cathode coating based on manganese dioxide. It was established that manganese oxide (III) contaminates the impregnating solution of manganese nitrate, from which the cathode coating on tantalum bulk-porous anodes is obtained by thermal decomposition. To reduce the EPS of the finished capacitor, a method is developed for removing manganese oxide (III) from the semiconductor coating by cleaning the precursor, manganese nitrate, and modifying the surface of the cathode coating with oxidizing agents. The proposed method can be recommended for practical implementation in the production of tantalum oxide semiconductor capacitors, which will improve the electrical characteristics by reducing the equivalent series resistance of finished products.

The changes in the composition of the residual fractions and the structure of the asphaltene molecules during the primary processing of heavy oil are investigated. It was established that the atmospheric-vacuum distillation of heavy oil is accompanied by the formation of additional resin-asphaltene substances (more than 20 mass %). The initiation of chemical reactions between oil components occurs at the stage of fuel oil production due to the destruction of mainly sulphur-containing fragments in asphaltene molecules. It was shown that during tar production, the destruction and elimination of asphaltene-saturated fragments occur with a decrease in the content of naphthenic and paraffinic carbon by 5.5 and 1.7 %, respectively. Recombination reactions between the resulting macroradicals of asphaltene molecules contribute to an increase in their aromaticity factor by 7.2 % and the average molecular mass by 190 Da. Collection of the fraction 350-450 °C leads to a decrease in the average molecular mass of asphaltenes by 425 Da with an insignificant redistribution of carbon in various structural fragments.

Processes occurring in the dumps of sulphide-bearing rocks had drawn the researchers' attention for a long time. Environmental hazards connected with the activity of mining industry facilities under the conditions of climate change can be estimated by modeling. Modeling was performed in the water-rock-atmosphere systems (software suite Selector), where rock is an average mineral composition of rocks from the Allarechensky Deposit Dumps of copper-nickel ores. The conditions for the carryover of different components during weathering of rocks in the dump were determined, and the effect of climatic factors on the formation of new phases was evaluated. It was demonstrated that abrupt temperature changes promote rock weathering. In addition to copper and nickel, potassium and aluminium will pass into solution during the cold period. Gibbsite and aluminium silicates will be formed during the warm period. Comparison of modeling results with field studies revealed the adequacy of the model and high degree of the interaction of rocks and atmospheric precipitation in the dumps. Evaporation gives rise to more acid solutions, increased transfer of nickel, copper, iron and sulphates into solutions. The basic premise is that the destruction of wastes mineral matrix occurs practically all the year round under the regional climatic conditions, due to the formation of highly mineralized solutions inside the dump body and on its surface. Atmospheric precipitation, filtered through rock fragments with high sulphide content, affects the hydrosphere causing an increase in the concentration of all the major ions (Clˉ, SO₄²ˉ, HCO₃ˉ, Na⁺, K⁺, Ca²⁺, Mg²⁺) by a factor of several units, compared to pure natural waters.

The effect of ionizing radiation on bituminous coal samples was studied. It was established that pre-treatment of coal leads to an increase in the amounts of oxygenated and asphaltenic fractions in extracts. The effect of ionizing radiation on subsequent thermal destruction of coal was shown. In the process of coking of the treated and extracted coal samples, the yield of coke residues with macroporous structure increased.

Review and analysis of the modern data on the content of phenol compounds in the plants of the Salix L. genus were carried out. The works aimed at the search for chemotaxonomic markers and their application in systematics are presented. It is demonstrated that the qualitative composition of phenol compounds is an invariable, stable sign for the taxons of the Salix genus. Phenol glycosides may be used to identify morphologically similar species and hybrid forms. Special attention is paid to the species that have been the subjects of investigations in different countries: S . babylonica L., S . alba L., S . raddeana Laksch. еx Nasarow, S . caprea L. and S . acutifolia Willd.

Influence of ionizing radiation on the physicochemical characteristics of poly-N-methylallyl-5-vinyltetrazole (MPVT-A) and the rheological kinetic properties of energy-rich compositions prepared from irradiated MPVT-A samples was studied. It is established that ionizing radiation can significantly reduce the induction time of solidification of the compositions based on MPVT-A.

The literature data on the research in the field of homo- and copolymerization of norbornene and its derivatives are discussed in the review. Due to specific structure, norbornene and its derivatives provide the basis to synthesize the polymers and copolymers with various functionalities, differing from each other in the structure and physical-mechanical characteristics of final products. Depending on polymerization conditions, the polymers synthesized on the basis of norbornene are characterized by high optical purity, high thermal and chemical stability, mechanical strength. Copolymers of norbornene with olefins and acrylic monomers combine the properties typical for norbornenes with such characteristics of polyolefins or polyacrylates as high adhesion, elasticity, flexibility of macromolecules, which promotes broadening of their application range. Thus, the availability of the raw material basis of norbornene and its derivatives, together with the unique performance characteristics of the polymers and copolymers based on them, attracts the attention of researches to the studies into the synthesis of new norbornene monomers and the synthesis of polymers and copolymers on their basis for use in various branches of industry. The data presented in the review provide evidence of the promising character of studies in the area of the synthesis of high-molecular compounds with valuable performance characteristics on the basis of norbornene hydrocarbons.

Regulation of the transport characteristics of oil is often implemented with the help of depressor and inhibiting additives. A characteristic feature of new developments in the area of oil additives is the composite nature (two or more components of the active substance), which provides their multifunctional action. Results obtained in the investigation of the effect of complex additives based on polyalkylacrylate (PAA) and petroleum-polymer resins modified through nitration (N-PPR) on the chilling temperature and viscosity of paraffin and high-paraffin oils of West Siberia, as well as on the amount and composition of asphaltic resinous paraffin sediments (ARPS) are presented. It is established that, in comparison with the additive based on PAA, the complex additive causes a decrease in the amount of ARPS (by 10 % as average), a two-fold increase in the depression of oil chilling temperature and a decrease in its dynamic viscosity. The efficiency of the complex additive was revealed to depend on the method of N-PPR preparation. The best results with respect to all parameters are demonstrated by the additives for which the N-PPR were synthesized by means of ion and initiated polymerization. It was shown in the evaluation of the surface activity of resinous asphaltene oil components and the components of the developed compositions that among the studied samples N-PPR are characterized by the lowest surface tension. The resins of oil kinds under investigation differ from each other in surface tension only insignificantly. Among all components, asphaltenes are characterized by the highest surface tension. A new complex additive based on PAA and modified PPR is proposed, which may be used to reduce the chilling temperature and viscosity of paraffin and high-paraffin oil, as well as the amount of ARPS formed in them.

The quantitative content of 22 chemical elements (As, Br, Co, Cr, Cu, Mn, Mo, Nb, Ni, Pb, Rb, Sc, Se, Sr, Ti, Zn, Zr, V, Y, Ca, Fe, K) in the vegetative organs of Hemerocallis hybrida was determined for the first time with the help of X-ray fluorescence analysis with synchrotron radiation (XRD). Comparative data on the elemental composition of leaves and rhizomes in the plants of varieties Speak to me and Regal Air in the forest-steppe zone of West Siberia are presented. The specific features of the content of 19 microelements and 3 macroelements in above-ground and underground organs were revealed. The concentrations of all elements in the leaves and rhizomes of Speak to me and Regal Air plants were at the maximum permissible level. The leaves of Regal Air were distinguished by the higher (by a factor of 1.5-7) content of molybdenum, bromine, chromium, rubidium, selenium. The concentrations of lead, strontium, yttrium, zirconium, niobium were 1.5-6 times higher in the leaves of Speak to me. Underground organs were found to be the richest in trace elements. It was shown that the total content of trace elements is 1.5-3 times higher in the organs of the Regal Air variety. The variety specificity of the quantitative content of chemical elements in vegetative organs is detected.

The necessity to introduce the principles of green economics into subsoil management as one of the most important branches of Russian economy affecting the quality of the environment to the highest extent is considered. The main kinds of the effect of mining and primary processing of mineral resources on the state of geological environment, surface relief and soil cover are presented, as well as the forms of the influence on human health for different stages of the industrial process. The long-term negative effect of the consequences of mineral resource mining is stressed, together with the high cost of recultivation and rehabilitation works. The major goals in the introduction of green approaches in subsoil resource management include improvement of the normative-legal basis of subsoil usage with respect to the ecological aspects of raw material mining and processing, the formation of the state authorities for geological management and innovative development of the economics of the country, broadening of the range of application of financial mechanisms for the technological renewal, public disclosure of the entire ecologically significant information on the companies involved in subsoil resource management.