Home – Home – Jornals – Chemistry for Sustainable Development 2022 number 2

This paper presents conventional and innovative technologies for wastewater and industrial solution purification from Ni²⁺ ions and accompanying non-ferrous metals. Several methods including sorption, extraction, flotation, chemical, electrochemical, membrane and microbiological separation of impurities from the liquid phase are introduced. Chemical methods involve nickel deposition in the form of insoluble compounds (hydroxide, carbonate, bicarbonate, sulphide, dimethylglyoximate), or metal powder by adding certain reagents. Carbon, aluminosilicate and some other inorganic materials in initial and pre-modified forms, as well as weakly acidic, strongly acidic, weakly basic, including chelate ion-exchange resins and fibres are used for sorption. The extraction of nickel ions from the liquid phase is carried out with the derivatives of organophosphorous, carboxylic acids, as well as with materials that combine the properties of solid sorbents and liquid extractants. Nanofiltration and reverse osmosis are the most relevant methods among the membrane purification methods. Foam separation of nickel ions during flotation is carried out using anionic and nonionic surfactants. Electrochemical methods include electrocoagulation, electroextraction, electroflotation, and electrodialysis using soluble and insoluble electrodes, as well as galvanic coagulation without connection to external power. Living and non-living biomass of some species of bacteria, fungi, algae, as well as their complex mixture in the form of activated sludge can be deployed for microbial extraction of nickel from aqueous media. The above purification methods are considered on the basis of case studies, both generally applicable and specific ones. Their advantages and disadvantages are briefly described.

The currently widespread methods of processing fuel oils obtained during the primary separation of oil are complex multistage processes, including preliminary vacuum distillation and subsequent cracking of the resulting vacuum gas oils, as well as the oxidation of residual tar into bitumens. For small-scale industries, such processes are costly and, in some cases, unprofitable. The article proposes a technology for thermolytic processing of fuel oil over a tin-lead melt in a semi-continuous reactor. The main advantages of the proposed technology are low process temperature and pressure close to atmospheric, as well as almost complete elimination of the formation of carbon deposits on reactor walls. The reported results describe experiments on thermal cracking of fuel oil carried out according to two kinds of destructive distillation: the classical version, and the version involving a tin-lead melt. It is shown that during destructive distillation on a tin-lead melt, deeper cracking occurs in comparison with classical destructive distillation. The content of gasoline fraction (IPB-180 °С) and diesel fraction (180-360 °С) in thermal gas oil obtained by means of classical destructive distillation is higher than in thermal gas oil obtained by destructive distillation on tin-lead melt, while the content of fractions boiling above 360 °C is lower. The group composition, density and dynamic viscosity of thermal gas oils differ insignificantly. For thermal gas oil obtained over a tin-lead melt, a slight decrease in sulphur content is observed. Analysis of thermal gas oils for tin and lead showed their absence. Thermal gas oils have a high content of aromatic compounds, which makes them a promising raw material for needle coke production. Multiple analysis of the tin-lead alloy after the completion of the process showed that the alloy was free from mechanical impurities present in the fuel oil, it also did not contain coke released during thermolysis, and the mass of the alloy remained constant, which means that in this case the alloy plays the role of an effective heat carrier, which makes it possible to deepen fuel oil thermolysis.

The methods of manufacturing the sintering additives to coal charges from the vacuum residues of visbreaking tar, one of the most widespread and large-tonnage products, are considered. The starting raw material was subjected to deep vacuum distillation on a laboratory unit and thermal oxidation in a batch reactor. Experimental samples of sintering additives were obtained, and the possibility to produce sintering additives of petroleum origin on this basis was investigated. The physicochemical characteristics of the obtained products were determined; the possibility of their transportation, crushing, mixing and use instead of sintering coal grades in coal coking charges was assessed. A comparison of the obtained sintering additives was carried out for different production methods: an increase in the extent of tar conversion in visbreaking, deep vacuum distillation of the visbreaking residue, and oxidation of the visbreaking vacuum residue. The possibility of the industrial production of sintering additives from visbreaking residues was evaluated on the basis of research results.

Results of the studies of powder and structural composites (plates) based on low-density polyethylene (LDPE 15803-020 and LLDPE 6101RQ) and ultra-high molecular weight polyethylene (UHMWPE from Braskem company) and inorganic additives (SiC, TiO₂, CaCO₃, SiO₂) within concentration range 0.05-70 wt. % are presented. It is established that ultradispersed inorganic particles promote a decrease in the amount of the crystalline phase of polymers and an increase in wear resistance for the samples: UHMWPE (containing 7 wt. % SiC ( S _sp = 10 m²/g)) - by a factor of about 150; LDPE 15803-020 (20 wt. % SiC ( S _sp = 6-10 m²/g)) - by a factor of 2-2.5. For LLDPE 6101RQ samples with the low additive content (0.05-5 wt. % ТiО₂, SiO₂, CaCO₃), tensile strength increases by 7-24 %, мodulus of elasticity (along the axis) increases by a factor of 1.2-1.4, and relative elongation at fracture decreases within the range of 13.5-38.0 %. The maximal increase in tensile strength is observed for samples containing 20 wt. % SiO₂ and 50 wt. % ТiО₂ (by 38.5 and 43.6 %, respectively), while relative elongation at fracture decreases 2.8 and 3.9 times, and мodulus of elasticity increases by a factor of 1.9 and 2.0, respectively. Comparative data on the oxygen permeability of the plates, with different methods for the initial components’ mixing, show that samples prepared by mixing the polymer with inorganic additives in a mixer (the amount of additives 5 and 20 wt. %) gave a decrease in oxygen permeability within 5.6-11.2 %, while the samples prepared through mixing in a planetary mill activator, AGO-3, showed a decrease in oxygen permeability in the range of 16.8-28.7 %, compared to the original sample.

The mechanisms of the coagulation-based water purification using titanium-containing coagulants were studied. Investigation of colloidal systems formed during hydrolysis of traditional coagulants based on aluminium and iron compounds, as well as innovative and promising titanium-containing coagulants, was carried out. The surface characteristics (surface charge, specific surface area) of hydrolysis products of titanium compounds were determined under conditions close to those of the coagulation water purification. The surface characteristics of the products of hydrolysis of traditional and titanium coagulants were compared. It has been established that the hydrolysis products of titanium compounds carry a negative charge on their surface, and their surface that is extremely developed in comparison with traditional coagulants, which indirectly confirms their ability to adsorb pollutants. The sedimentation characteristics of the resulting hydrolysis products of various coagulants were studied. It was shown that the coagulation slimes formed as a result of the use of titanium-containing reagents have a larger flake size, which means they quickly settle to the bottom during settling. The increased efficiency of complex titanium-containing coagulants (Al-Ti) due to the phenomena of charge neutralization and nucleation on the surface of hydrolysis products of titanium compounds has been confirmed and scientifically substantiated. Evaluation of the efficiency of titanium-containing coagulants in the purification of drinking water from the Moscow water intake was carried out. It was found that in the purification of water from the surface water intake, titanium-containing reagents significantly exceeded traditional reagents in the effectiveness (a decrease in the content of suspended solids, colour index), and residual concentrations of titanium compounds in purified water meet the requirements of drinking water quality standards (0.1 mg/L). The sediments obtained with the use of titanium-containing coagulants were distinguished by an increased sedimentation rate and more readily gave up moisture during the filtration process, which would allow reduction of the dimensions of the treatment equipment.

Concentrations of organochlorine compounds (OCs) were determined, and comparative analysis of OCs in the bottom sediments of the Chernaya river, small lakes of the Baydar valley, the Sevastopol Bay and the Chernorechensky reservoir, sampled in 2008 and 2019-2020, was carried out. A noticeable difference in the levels of pollution with OCs in the river, lakes and the bay was detected. This concerns mainly such OCs as polychlorinated biphenyls (PCB), the content of which in sediments of the studied areas varied within a wide range - from 0.5 in lakes to 900 ng/g dry mass in the Sevastopol bay. Increased anthropogenic pressure on the river water area in the region of Baydar valley and in the estuary area has led to the formation of zones with the local maxima of the concentrations of PCB and organochlorine pesticides (1,1,1-trichloro-2,2-bis(chlorophenylethane), DDT) in the bottom sediments of the Chernaya river. In the Baydar valley, the sediments in lakes were on average less contaminated than river sediments, which is due to the isolation of lake ecosystems; they may be classified as non-polluted and weakly polluted. The maximal OCs concentrations were detected in the Sevastopol Bay. The ratio of DDT metabolites in the composition of organochlorine pesticides depended on redox conditions in bottom sediments: under anaerobic conditions of the Sevastopol Bay, DDT was transformed into DDD (1,1-dichloro-2,2-bis(4-chlorophenyl)ethane), under aerobic conditions in the river sediment - into DDE (1,1-dichloro-2,2-bis-(4-chlorophenyl)ethylene). Reconstruction of sedimentation geochronology using radiotracer methods shows that the variability of OCs content at different depths of fresh-water sediments depended on the temporally varying amounts of OCs income into the water areas but not on the natural conditions of sediment formation. According to estimates, at present, the runoff from the Chernaya river contributes not more than 14 % ∑DDT and 4 % ∑6PCB into the bottom sediments of the Sevastopol Bay.

The catalytic properties of ZSM-5 type zeolites modified with copper, zirconium and boron in the process of obtaining high-octane gasoline from the straight-run gasoline fraction of gas condensate have been studied in a flow-through installation at atmospheric pressure without hydrogen within the temperature range 350-430 °C. Cracking and aromatization of hydrocarbons mainly take place on non-modified HZSM-5 zeolite; with an increase in reaction temperature from 350 to 430 °C on HZSM-5, an increase in the content of aromatic hydrocarbons (from 10.8 to 16.9 mass %) and a decrease in the yield of liquid hydrocarbons (from 68.6 to 60.8 mass %) is observed. Modification of HZSM-5 zeolite with copper significantly changes the content of high-octane components in the catalyzate. An increase in copper concentration in HZSM-5 up to 2.0 mass % leads to an increase in the ability of the catalyst to provide isomerization and aromatization. At the optimum temperature (380 °C), the content of isoparaffinic and aromatic hydrocarbons in the catalyzate increases up to 36.8 and 24.6 mass %, respectively. An increase in the concentration of copper in HZSM-5 up to 3.0 mass % promotes an increase in the aromatization ability of the catalyst. Modification of the catalyst 2 % Cu/HZSM-5 with boron in the amount of 0.5-1.0 mass % has a small effect on its isomerization and aromatization properties, but significantly increases the yield of liquid products. It is found that the modification of the catalyst 2.0 % Cu-1.0 % B/HZSM-5 with zirconium in the amount of 0.5-1.5 mass % significantly increases the content of isoparaffinic hydrocarbons in the catalyzate (42.1-43.5 mass %). The highest activity is exhibited by the bimetallic catalyst consisting of 1.0 % Zr-2.0 % Cu-1.0 % B/HZSM-5, which allows obtaining the gasoline fraction with 88-94 octane number according to the research method. The addition of boron in the amount of 1.0 mass %, followed by the introduction of zirconium and copper, makes it possible to increase the duration of catalyst operation by up to 200 h. With respect to the content of isoparaffinic and aromatic hydrocarbons and benzene, the gasoline fraction corresponds to the Euro-4 and Euro-5 class. The possibility of refining low-octane straight-run gasoline fractions in the presence of a bimetallic catalyst under unconventional conditions without hydrogen supply to the reaction zone at atmospheric pressure is demonstrated.

As a result of sedimentation, suspended particles carry chemical pollution from the surface layer of water into bottom sediments, playing a significant role in waters’ self-purification from mercury. For the purpose of establishing the features of mercury distribution in the surface water of coastal and open-sea areas and concentrating it in the suspended matter, mercury concentrations were measured in water sampled in different seasons of the years 2018-2019 from the surface water layer of the Black Sea, and empirical dependencies of the parameters of mercury concentrating by the suspended matter on the seasons and depths of the water areas were determined. It is demonstrated that dissolved mercury forms dominated in the Black Sea during the period under investigation, regardless of the seasons. The concentration of dissolved mercury form in the water of the Black Sea varied from 10.0 to 130.0 ng/L, and the average concentration was 54.9 ng/L. The coefficient of mercury accumulation by suspended matter (K_ss) was determined, which varied within the range (0.01-3.33)•10⁶. The values K_ss > 10⁶ provide evidence of the high concentrating capacity of suspended matter in sea water and prevalence of sedimentation over other biogeochemical mechanisms of water self-purification. The formula for calculating the percentage pool of mercury in suspended matter was analysed. The values of the percentage pool of the suspended form of mercury were obtained, ranging from 3.2 to 75 % of the total mercury content in the surface water of the Black Sea for its coastal and open water areas in different seasons of the year.

Mumijo is a product of natural origin, composed of a complex mixture of organic compounds and exhibiting physiological activity in some cases. The Altai mumijo is widely known in Russia, but Tuvinian mumijo has been studied much less. The data on the location of mumijo in the Republic of Tyva, its elemental composition, isotopic composition of carbon, amino acid spectrum, and mineral formations associated with mumijo are presented. The investigated mumijo is a waste product of small rodents, which underwent aqua transfer, weathering and bacterial processing.

The carbon isotope composition analysis of 51 melliferous plants species of the Tomsk region, 35 samples of pollen load, 77 samples of honey and 36 samples of dead bees taken from different geographic regions of Russia was carried out. The stable carbon isotope ratios were measured to reveal the applicability of isotope ratio mass spectrometry to detect honey adulteration with sugar syrup and to determine the geographical origin. Seven adulterated honey samples were identified with the help of the method of honey adulteration detection based on comparison of the ¹³C/¹²C isotope ratio in honey sample and in the protein isolated from honey, which was an internal standard. Some differences in the carbon isotope composition (δ¹³C) are observed for honey samples from the Tomsk Region collected in 2019 and 2020, which points to the necessity of further studies of the influence of climatic conditions and honey harvesting season on the ratio of stable carbon isotopes in honey. Carbon isotope analysis demonstrated differences between honey samples differing from each other in geographical origin. Higher δ¹³C values are typical for honey samples from the European part of Russia and the Black Sea region. The δ¹³C values of honey from Siberian regions with a lower average temperature or higher air humidity are lower. For local areas, the “canopy effect” was revealed, in which the carbon isotope composition of the pollen load for forest ecosystems is depleted in ¹³С isotopes, compared to meadow ecosystems. Trophic enrichment values (Δ¹³С = 1.0±1.2 ‰) in the chain “pollen load - bee” were also determined.