Home – Home – Jornals – Chemistry for Sustainable Development 2017 number 2

Organic synthesis products are widely used in the daily life beginning with medicinal, sweet preparations, lacs, dyes up to plastic, rubber, etc . Benzene that is amongst the top ten largest of the biggest substances of the chemical industry being highly liquid and high priced products. In this regard, this product is manufactured both at petrochemical enterprises and their by-product coking plants. Coal crude benzene contains unsaturated and sulphur compounds and it is required to preliminarily purify it from these undesirable impurities to obtain pure products from it. Even insignificant amounts of sulphur in benzene and toluene when using them in organic synthesis processes cause fast poisoning of the catalyst, and resinous substances formed resulting from polymerization of unsaturated compounds cover the catalyst surface and thereby deactivate it. Analysis of the published works on purification methods of coal crude benzene from unsaturated and sulphur compounds was performed in the present review. The advantages and shortages of the known methods were considered. Prospects of ozonolytic purification of coal crude benzene were demonstrated.

Tellurium reduction in alkaline solutions in the concentration range of tellurite ions of 0.001-1 М was studied by a voltammetric method on updated solid indicator electrodes (Au, Pt, Ni and graphite). It was detected that a change in the form of the cathode current-potential curve was observed for all electrodes at constant alkali concentrations and an increase in the tellurium concentration in solutions above 0.2-0.3 М. It was found that a change in the ratio of hydroxide and tellurite ions concentrations could be one of the probable causes for this. An opportunity of using the studied electrodes for express control of the tellurium concentration in the alkaline electrolyte used to obtain high purity tellurium was demonstrated.

Samples of an Al-Fe alloy of composition of (2.15±0.08) mass %, admixtures of not more than 0.2 mass %, were studied. It was demonstrated by XPA that the intermetallide of composition Al_3.2Fe and polycrystalline aluminium were formed at alloying of metals. The interaction of Al-Fe alloy samples with liquid Ga-In eutectics was studied by methods of scanning electron microscopy and energy-dispersive X-ray spectroscopy. It was found that an Al-Fe alloy became activated slower by liquid Ga-In eutectics than polycrystalline aluminium and Al-Ni alloys. The intermetallide phase of Al_3.2Fe composition does not undergo significant chemical changes. It was demonstrated by multiple frustrated total internal reflection IR spectroscopy that aluminium chloride complexes of various compositions were in situ formed during the interaction of activated samples of an Al-Fe alloy with tert-butyl chloride. The complexes showed catalytic properties.

The preparation of new derivatives of polysaccharides showing the biological activity, precisely, antimicrobial properties remains quite a priority task not only in chemistry of high- molecular compounds but also in pharmaceutics and medicine, since some antimicrobial compounds obtained on the basis of natural polymers are superior to synthetic low-molecular weight antimicrobial compounds on some criteria. New water soluble pectin derivatives containing sulphamic groups in their structure were obtained in this work by the interaction of sulphamic acid with polysaccharide aldehyde groups. The structure and composition of the resulting compounds were studied by IR spectroscopy, elemental (nitrogen, sulphur) and X-ray crystal analyses. Sulphamic pectin derivatives with various contents of sulphamic groups were obtained by changing the concentration of sulphamic acid in relation to dialdehyde pectin derivatives. The optimum ratio of reactive components that is -СНО/NH₂SO₃H = 1.0 : 2.5 and the reaction time of 45 min were found. Study results of antimicrobial action of antimicrobial action of the synthesized sulphamic pectin derivatives were presented. The biological activity of the resulting compounds was studied by the disk diffusion method in relation to gram positive and gram positive negative bacteria. Direct dependence of the antimicrobial activity of the studied preparations on the quantitative content of sulphamic groups in pectin was found. It was determined that sulphamic pectin derivatives with a substitution degree of 35.0 showed antimicrobial activity in relation to Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Proteus vulgaris, Streptococcus faecalis, Streptococcus pyogenes, Streptococcus faecalis, Pseudomonas aeruginosa with a concentration of 50 μg/mL. Antimicrobial action begins to decrease with the decrease in the number of sulphamic groups. Study results of acute toxicity of sulphamic pectin derivatives were presented. According to the results, they can be referred to class V almost nontoxic substances.

The activity in the carbon monoxide (CO) oxidation reaction of МеО _х /М and Pd/МеО _х /Ni-Al/НС catalysts where MeO _x : Al₂О₃, Al₂О₃-СеО₂, Al₂О₃-MnО₂ carrier is applied to Ni-Al/НС (grids made of HC with an evaporated Ni-Al layer) was studied. Samples, in which grids made from fechral and nichrome were used, were prepared for comparison. It was demonstrated that intermediate Ni-Al coating itself serving to increase adhesion of oxides to a metal substrate exhibited the catalytic activity. The most active samples activated and not activated by palladium were determined according to the results of catalytic trials. All catalysts were characterized by X-ray phase analysis, scanning electron microscopy methods. The most active Pd/Al₂O₃/Ni-/HC sample was additionally studied by scanning electron microscopy (SEM) with local analysis.

Potassium sorption processes from aqueous solutions of KH₂PO₄, K₂HPO₄, K₃PO₄, KCl, and KNO₃ by porous substrates of bast and birch bark were studied. The effect of the nature of the salts on potassium sorption was found. It was demonstrated that the investigated salts by their capacity to potassium sorption could be placed in the following row: K₃PO₄ > К₂HPO₄ > KCl > KNO₃ > KH₂PO₄. Comparison of sorption of potassium and phosphates from solutions of phosphorus-containing salts was made. The effect of pH of solutions and the background electrolyte on potassium sorption from various salt solutions was studied. It was found that the application of the background electrolyte exerted a positive effect on potassium sorption from solutions of KH₂PO₄, KCl and KNO₃. It was demonstrated on an example of potassium chloride and potassium nitrate that an increase in the pH of solutions of the salts to 10.7 led to a larger increase in potassium sorption in comparison with the effect reached in the presence of the background electrolyte. It was found that the highest sorption of potassium (А_∞) was reached from solutions of K₃PO₄ and KCl (рН 10.8) and amounts to 32.55 и 30.20 mg/g, respectively. Potassium sorption isotherms obtained under various conditions, for which values of the constant К_L and the limiting sorption А_∞ were determined according to the Langmuir equation, are given. Potassium sorption values were calculated using these significations and compared with the experimental data. It was demonstrated that porous substrates of bast and birch bark showed close sorption activities in relation to potassium. The substrates investigated exceed activated carbon of birch wood.

Assessment of the chemical composition of snow melt water was carried out in the zone of influence of the aerial technogenic load from the largest source of emissions in the territory of the Murmansk Region that is a copper-nickel combine (Monchegorsk area) of the Kola Mining and Metallurgical AO. The results of direct analytical determination in the framework of annual monitoring were complemented by the results of retrospective analysis by means of physicochemical modelling (Selektor program complex). The obtained results testify a change in the deportments of elements in snow melt water when decreasing the level of the multicomponent aerial technogenic load after production modernization. The minimisation of dust emissions and an increase in the efficiency of purification of fume gases from sulphurous anhydride contributed to a shift of the redox potential of snow melt water from the negative to positive region and a transfer of some pollutants elements with a variable valence into the oxidized form. A decrease in dust emissions that exerted the alkalinizing effect contributed to an increase in water acidity and consequently, an increase of the proportion in them of the aluminium ionic form recognized most toxic for biota. The sulphates concentration in the atmospheric deposition of the winter season currently does not go beyond All-Russian weighted average concentrations even in the local area of model objects. Increasing the proportion of copper chloride complexes was noted in snow melt water, a basic pollutant, which testifies a possible increase in its migratory activity that is driven by an increasing effect of sea aerosols when softening the regional climate. The practical significance of the work is expressed in an opportunity to reconstruct element speciation in melt water both during retrospective analyses and planning the procedure of biotesting in engineering and environmental survey and monitoring studies.

Chemical transformations of petroleum extracts of peat wax occurring in the process of mechanochemical treatment (cavitation) of the most typical types of high-moor peat for the territory of Khanty-Mansiysk Autonomous District - Yugra were studied. It was demonstrated that hydrolysis of ester bonds in the composition of wax molecules proceeded in alkaline media resulting from mechanochemical treatment of peat raw materials. Alcohol groups of waxes formed as result of hydrolysis are subjected to oxidation to aldehyde groups followed by condensation. Peat waxes are capable of entering into reactions with ammonia molecules, which is confirmed by elemental analysis results during the processes listed. It was suggested that free-radical states, as well as hydrogen peroxide formed due to mechanochemical treatment of aqueous alkaline media were a source of an oxidizing agent. Additionally, based on elemental analysis data and IR spectra obtained, a hypothesis was put forward of mainly the aldol condensation mechanism for processes initiated by mechanochemical treatment. A preliminary conclusion was made of the fact that only a part of peat waxes participates in the stated processes, which allows using this type of raw materials more rationally, simultaneously obtaining humic acids and bitumenols from it. It was demonstrated that qualitative characteristics of peat wax isolated from oxidative aminolysis products met requirements for technical conditions imposed on raw peat wax.

The sorption process of carbon dioxide by an ionic liquid monomer (ILM) that is 2-methacryloxyethyl diethylammonium chloride, homopolymer based on it, as well as copolymers obtained by copolymerization of the indicated monomer with styrene and methacrylic acid at the molar ratios of 1 : 2 and 1 : 1, respectively, was studied. A relatively high level of absorptive capacity of ILM in comparison with the homopolymer and copolymers based on it was found. The observed relatively high absorptive capacity of СО₂, of the studied ILM is explained by the interaction of the contrarily charged fragment of the monomer molecule. Thus, a decrease in the absorptive capacity of samples in the transition from the monomer to the homopolymer on its base and further to copolymers distinguished by the content of ILM links in the macrochain composition, and consequently, fragments with opposite charges. It was demonstrated that the sorption process of carbon dioxide of the samples studied was reversible and one could reach complete desorption of CO₂ with the recovery of their adsorptive effect. Based on the results obtained, the ILM indicated and its homopolymer and copolymers on its base can be recommended as sorbents for carbon dioxide adsorption.

Sapropels and carbon-mineral composites obtained by thermal treatment of sapropel at various temperatures were studied by X-ray phase analysis (XPA), transmission electron microscopy (TEM), BET and small angle X-ray scattering (SAXS) methods. It was found that the mineral phase in sapropels formed both elongated layered sapropels particles with fractal dimensions and compact large quartz particles. It was demonstrated that heating sapropels at 300°С led to dispersion and stratification of mineral particles in sapropels, but herewith, the organic phase blocked up the pores formed and hinders an increase in the specific surface of the composite obtained. An increase in heating temperature to 600 °С leads to freeing the porous space from the carbon phase and increasing the total specific surface. A further increase in heating temperature to 900 °С gives partial sintering of the mineral phase and transitioning from fractal volumetric structures to surface ones, herewith, the value of the specific surface of composition materials almost does not change.

It was found that mercury contents in saline soils of Bol’shoye Yarovoye Lake met the average content in solonetz soils of the steppe zone of Altai Territory. Differences between types of soils are explained by the peculiarities of solonetz and solonchak processes. The distribution of mercury in bottom deposits is uneven both along cores on depth of individual wells, and in different wells. The average content of mercury and the value of the Hg/Al ratio in bottom deposits are significantly higher than their values in soils because of local pollution. Low mercury contents and Hg/Al ratios were found in coastal wells only. Factor analysis and pair correlation method detected differences in correlations of mercury between soils and bottom sediments both in granulometric fractions, and the initial samples. Correlation analysis results in the initial samples of soils and bottom sediments give the overall picture of mercury distribution in the sedimentation process. Mercury in soils has positive correlations with the terrigenous component that is its major natural source. A negative correlation with the “carbonate” group (Са, Mg, Sr) and antimony is typical. Mercury in bottom deposits has positive correlations with antimony and manganese, and is bound with the major composition of precipitates indirectly only. These results argue of a change in the deportment of mercury in the sedimentation process, which confirms its local entrance into precipitation from a technogenic source that is accompanied by antimony.

An opportunity for bioremediation of ground water polluted by oil products through a system of observation wells was studied. The activity of bioremediation processes was assessed by a change in the content of nitrogen (ammonia, nitrate, and nitrite) in water, the number of aerobic and anaerobic microorganisms and oil products. Microbial growth was stimulated by the introduction of mineral fertilizers into ground water as sources of N and P. Prior to treatment, the number of ammonifying and hydrocarbon oxidizing microorganisms in water collected from wells at polluted sites did not exceed 10⁵ CFU/mL and 10³–10⁵ CFU/mL, respectively. In response to nutrients feeding that limits the growth, the number of aerobic microorganisms increased by 3–4 orders. The number of ammonifying microorganisms increased to 1.8 × 10⁸ CFU/mL, hydrocarbon oxidizing — 2.3 × 10⁷ CFU/mL. An increase in the concentration of ammonia nitrogen (to the values above 50 mg/L) happened in ground water with delay of 2–6 weeks. Dynamics analysis of the chemical composition of ground water by the data of all wells demonstrated that a concerted fluctuation of the activity of nitrification and denitrification processes proceeded in oil products biodegradation in the active phase, and accordingly, of ammonium and nitrate concentrations. Predicting the chemical composition of ground water using a neural network confirmed the same. The content of oil products in ground water decreased by 65–97 %.

A new gas-phase process of halogen-free dimethyl ether (DME) carbonylation to methyl acetate is a promising eco-pure preparation method of methyl acetate due to excluding methyl iodide, replacing methanol for cheaper raw materials that are DME and the removal of the separation stage of the reaction products of the catalyst and methyl iodide. The work presents studying an opportunity of using promoted by silver or copper as catalysts for this reaction. Catalysts with composition of 1 % Ag/Cs_1.5H_1.5РW₁₂O₄₀, 1 % Cu/Cs_1.5H_1.5РW₁₂O₄₀ и Cs_1.5H_1.5РW₁₂O₄₀ were studied by BET, X-ray phase analysis (XPA), scanning electron microscopy (SEM) and IR spectroscopy of adsorbed pyridine. It was demonstrated that the specific surface of samples was about 60 m²/g, the concentration of strong BrØnsted acid sites (BAS) was found at a level of 130 μmol/g, the phase composition of the promoted samples fully corresponded to the initial Cs_1.5H_1.5РW₁₂O₄₀ sample and represented a mixture of two phases that are heteropolyacids and acid cesium salt. High concentrations of BAS demonstrate superacid character of the resulting catalysts capable of activating a C-O bond in the DME molecule. Trials of the samples under industrial catalysis conditions (pressure of 10 atm, temperature of 200 °С, the composition of the initial mixture of DME/CO = 1 : 10) demonstrated that a 1 % Ag/Cs_1.5H_1.5РW₁₂O₄₀ catalyst exceeded the activity of the initial acid Cs_1.5H_1.5РW₁₂O₄₀ catalyst in 2 times, the selectivity by the target product methyl acetate is 60 %. The use of 1 % Cu/Cs_1.5H_1.5РW₁₂O₄₀ does not lead to a change in the activity of Cs_1.5H_1.5РW₁₂O₄₀, the selectivity reduces to 40 %. The data obtained can serve as a basis for elaboration of a silver-containing highly effective catalyst for eco-pure halogen-free DME carbonylation to methyl acetate.

An approach was disclosed to the development of mathematical models of industrial processes using quantum chemical calculation methods of thermodynamic parameters of target and side reactions in combination with experimental data analysis of the operation of an industrial transalkylation process that is one of the preparation stages of ethylbenzene. A scheme of transformations in the transalkylation process was elaborated, thermodynamic parameters of target and side reactions were determined, a kinetic model was compiled and its parameters defined. Adequacy of a model implemented in the HYSYS medium was tested resulting from comparison with industrial data. Application prospects of the developed mathematical model for the transalkylation process to increase energy and resource efficiency of ethylbenzene production were noted from the viewpoint of an increase in process selectivity and minimization of costs on developing a given quantity of the products.