Atomic Absorption Analysis Research Articles

Hydrothermal precipitation of copper from leaching solutions of metallurgical dusts

In this work, we aim to establish the main regularities of hydrothermal precipitation of copper from the previously unstudied sulfuric-nitric acid and sulfate solutions of atmospheric and autoclave processing of metallurgical dusts. Pyrite was used as a sulfidizer. The elemental composition of the products was determined by X-ray fluorescence, inductively coupled plasma atomic emission spectrometry, and atomic absorption analysis. It was found that copper precipitation by the proposed technology enables its recovery at a level of more than 95%. For sulfate solutions with a high arsenic concentration, a two-stage scheme of oxidation-hydrothermal treatment with the following parameters was proposed: temperature 180°С, duration 2 h, oxygen consumption 0.026 dm3/g pyrite (for the 1st stage), and 200°С and 2 h (for the 2nd stage). Extraction in the cake amounted to 95.4% of copper (in the form of Cu2S) and 91.4% of arsenic (in the form of FeAsO4), which allowed further separation of these metals by flotation. An autoclave treatment of a Cu–Zn–Fe–As–NO3 solution in the presence of pyrite at 180–220°С produced the activation energy values (kJ/mol) corresponding to the kinetic regime calculated by the two methods: 64.6 by the conventional method and 60.5 by the shrinking core model. The kinetic parameters of CuSO4–H2SO4–FeS2–H2O and CuNO3–H2SO4–FeS2–H2O systems were also determined. Flotation enrichment of copper autoclave precipitation cake was shown to result in a high degree of Cu and As separation, with the recovery amounting to Cu ˃ 95% and As ˂ 5%. Precious metals contained in pyrite are transferred to a flotation concentrate by 92.7% (Au) and 96.5% (Ag). The composition of the resulting flotation concentrate comprised (%): 12 Cu; 37 Fe; 38 S; 13 other elements. It is shown that, in order to obtain a product with the required content of copper, flotation concentrate should be separated into pyrite and copper concentrates followed by an additional flotation of primary copper concentrate in an alkaline medium in the presence of lime. Hence, our study has established the main regularities of hydrothermal precipitation of copper from the sulfuric-nitric acid and sulfate solutions of atmospheric and autoclave processing of metallurgical dusts.

Medium scale-up synthesis of nanomaghemite as an inhibitor of cadmium uptake in seedlings of Theobroma cacao L

The aim of this research was to show that the absorption of divalent cadmium ions (Cd2+) in Theobroma cacao L. seedlings can be controlled and adjusted by remediation with maghemite (γ-Fe2O3) nanoparticles (NPs), i.e., leading to the low tolerance limits established by the European Union (EU) in 2014 for Cd in products made from cocoa. The research had two stages; the first one involved the medium scale synthesis of 92 g of 15 nm γ-Fe2O3 NPs via room temperature chemical co-precipitation of ferrous salts and their characterizations using diverse physicochemical techniques. In the second stage, and for the first time, three doses of these γ-Fe2O3 NPs (1, 2, and 4 g) were applied to the substrate of cocoa seedlings of genotypes ICS 39, ICS 95, and CCN 51 for three months of exposure. A morphological analysis revealed non-significant toxic effects on the seedlings’ height, leaf area, and stem diameter among the genotypes and tested doses. The results of the atomic absorption analysis of the treatment with 4 g of γ-Fe2O3 NPs showed a concentration of 0.10 mg kg−1 of Cd2+, a limit lower than the control and the recommended value by the 2014 EU regulation. Thus, the transport and/or absorption of the Cd2+ toxic metal were significantly inhibited, since up to 74 % of Cd2+ uptake in the genotype ICS 95 was experimentally observed. Also, the environmental Fe-dynamics in the seedlings and soils demonstrated no transport of γ-Fe2O3 NPs to the seedlings. Thus, the study found that the Cd2+ adsorption in remediated soil using γ-Fe2O3 NPs involves three steps: electrostatic exchange, Fe-oxide adsorption, and substrate-γ-Fe2O3 NPs complexation and precipitation.

MACRO- AND MICROELEMENT COMPOSITION OF THE HERB AND ROOTS OF HAPLOPHYLLUM DAURICUM (L.) G. DON.

Haplophyllum dauricum is a rich source of lignans with antitumor activity. It has been actively used in the practice of Traditional medicine. In addition to lignans, the chemical composition of the species is represented by coumarins, flavonoids, alkaloids and essential oils. However, the composition of the elements of the species, which are necessary for the development of quality criteria of medicinal plants, has not been studied before. In this regard, the purpose of the work was to study the content of macro- and microelements in the aboveground and underground parts of Haplophyllum dauricum of the flora of Buryatia and Transbaikal territory. The content of the following elements was determined by inductively coupled plasma atomic emission spectrometry: Li, Be, Na, Mg, Al, P, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Zr, Mo, Cd, Sb, Te, Ba and Pb. The content of Hg was determined by the "cold steam" method using an atomic absorption analyzer. According to the obtained data, Haplophyllum dauricum is a rich source of calcium, potassium, magnesium and phosphorus, which were dominant. Among the microelements, iron and titanium were in highest concentration, which were accumulated mainly in the underground part of the plant. The content of heavy metals did not exceed the maximum permissible concentration established by the State Pharmacopoeia of the Russian Federation.

A technology for gold extraction from tailings resulting from polymetallic ore beneficiation

We propose a technology for processing of copper-zinc ore flotation tailings with the purpose of extracting gold using ultra-low (10–30 mg/dm3 ) concentrations of NaCN. The material composition of the starting materials was examined using the methods of inductively coupled plasma, gold assay atomic absorption and X-ray diffraction analysis. The NaCN concentration in solution was determined by titrimetric and photometric methods; pH levels were determined by potentiometric analysis. The laboratory studies established optimal conditions for cyanidation of tailings resulting from flotation beneficiation of copper-zinc ores, which underwent preliminary lime treatment: mass fraction of the 0.071-mm mesh minus – 70.5%; duration – 8 h; NaCN consumption – 0.3 kg/t (at a concentration of 30 mg/dm3 ); L:S =1:1. Under these conditions, the gold extraction rate amounted to 32.0–33.6%. Pre-grinding of flotation tailings to the size of 90% of the 30 mm mesh minus led to an increase in gold extraction of up to 41.5–44.7% at an NaCN consumption of 0.6 kg/t of the same concentration and L:S =1.5:1. The results obtained served as the basis for experimental cyanidation of waste tailings according to two schemes, i.e., using tailings of initial coarseness and pre-ground tailings. A good agreement was achieved between the laboratory and experimental results. At present, the use of pre-ground tailings seems unreasonable economically, due to high costs of NaCN (0.6 kg/t vs 0.3 kg/t) and active chlorine (5.6 kg/t vs 1.2 kg/t). According to pilot tests on a flotation tailing sample weighing 67 t (with an Au content of 1.35 g/t), the gold extraction level was 31.9% at an NaCN consumption rate of 0.135 kg/t. As a result, we propose a technology of gold extraction from flotation tailings of copper-zinc ore based on the application of ultra-low concentrations of NaCN. The expected profit can amount to 1276.74 mln RUB per year, with the economic efficiency of 88% and the payback period of 1.4 years).

Development of a Predictive Model for Iron Levels in Bovine Muscle Tissue Using Hair as a Predictor.

The assessment of iron levels in cattle muscle tissue is crucial for livestock management because it influences both animal health and meat quality, key factors in sustainable development. This study aimed to develop an optimal model for noninvasively predicting the iron content in Hereford cattle muscle tissue, contributing to a comprehensive understanding of the animals' elemental status. The research involved the atomic absorption analysis of muscle tissue and hair samples from cattle. A regression model was constructed using the least squares method to identify the most effective approach. These findings have ecological applications, aiding in evaluating environmental health and establishing acceptable iron thresholds for animals. The proposed mathematical model utilizing biomarkers (levels of Mg, K, Fe, Al, Cr in hair) will allow for the assessment of iron levels in cattle muscle tissue throughout the period of productive use, with the possibility of adjustment and tracking the changes in elemental status over time. The utilization of the developed method will enable the diagnosis of animal elementosis and assessment of the iron level burden. Subsequently, this will allow for the improvement of the qualitative characteristics of the final product. Thus, the obtained data contribute to fundamental knowledge regarding the content and variability of iron levels in the muscle tissue of cattle.

Atomic absorption determination of copper and zinc in pharmaceutical preparations

The effect of Triton X-100 surface-active substance on the value of the analytical signal during the atomic absorption determination of copper and zinc was studied. It was shown that the maximum value of the analytical signal in the determination of analytes is achieved when Triton X-100 is used at a mass fraction of 5%. The sensitivity of the atomic absorption determination of copper increases by 1.74 times and that of zinc by 1.58 times. Sample preparation of pharmaceutical substances was carried out using ultrasound treatment. The most complete extraction of metals was achieved when the samples were treated with ultrasound for 25 minutes, and homogeneous solutions were obtained. The use of acetylacetonates of metals as standard samples of the composition increased the accuracy of copper and zinc determination due to the similarity of the calibration and analyzed solutions. The correctness of the result of the atomic absorption analysis was checked by the "injected-found out" method and by varying the weight of the sample. It was established that the systematic error is not significant. The limits of detection of copper (Cmin=0.002 g/ml, Ctheor=0.004 g/ml) and zinc (Cmin=0.003 g/ml, Ctheor=0.004 g/ml) were determined by the atomic absorption method, they are lower than those given in literature.

Influence of Ultrahigh Dilution Treatment of the Charge on the Growth and Spectroscopic Properties of Nd:MgMoO4 Potential Laser Crystal

The influence of the charge treatment by ultrahigh dilution (UHD) technology on oxide single crystals grown by the Czochralski technique was studied for monoclinic MgMoO4 crystals doped by 1 at. % of Nd3+ ions. The series of 10 Nd:MgMoO4 crystals was grown from the charges that were subjected to UHD treatment, as well as from the charges treated with two types of control or with no special treatment at all. The grown crystals were studied by X-ray powder diffraction analysis, inductively coupled plasma atomic emission spectroscopy, mass-spectrometry, optical absorption, emission spectroscopy and luminescence kinetic analysis. We found that: (i) wetting of MgO + MoO3 mixture by a water-ethanol solution before calcining leads to some enrichment of the mixture with MoO3, whereas the wetting of the charge after the calcining leads to some enrichment of it with MgO; (ii) congruent melting composition of MgMoO4 crystal is in the field of some MoO3 excess; (iii) the solid-phase solubility of the excess MoO3 in MgMoO4 probably does not depend on temperature, whereas the solid-phase solubility of the excess MgO in MgMoO4 crystal depends on temperature. We suggest that the corresponding solidus line passes through the range of retrograde solubility; (iv) the crystals grown within this range are characterized by the enhanced Nd3+ segregation coefficient between the crystal and the melt (approximately 0.006 versus 0.004); (v) unit cell parameters of MgMoO4 crystal with the excess of MoO3 are larger than those of the crystal of the stoichiometric composition and of the crystal with the excess of MgO; (vi) the shapes of the optical absorption and luminescence spectra of Nd:MgMoO4 crystal do not depend on the charge treatment; (vii) luminescence decay kinetics are single-exponential for all the studied crystals, the luminescence decay time being different for the crystals grown from the charges that underwent different types of treatment; (viii) the luminescence intensity of Nd:MgMoO4 crystal grown from the charge that underwent UHD treatment before calcining (solid-phase synthesis) is reduced by an order of magnitude in comparison with the other studied crystals.

Magnetically recoverable Fe3O4@SiO2@SBA-3@2-ATP-Cu: an improved catalyst for the synthesis of 5-substituted 1H-tetrazoles.

Functionalization of Fe3O4@SiO2@SBA-3 with double-charged 3-chloropropyltrimethoxysilane (CPTMS) and 2-aminophenol, followed by mechanical mixing of the solid product with copper(i) chloride produces a new, greener and efficient Fe3O4@SiO2@SBA-3@2-ATP-Cu catalyst for the synthesis of 5-substituted 1H-tetrazoles. XRD, SEM, atomic absorption, TGA, N2 adsorption-desorption, and VSM analyses were performed for the characterization of the Fe3O4@SiO2@SBA-3@2-ATP-Cu structure. Nitrogen adsorption-desorption analysis revealed that Fe3O4@SiO2@SBA-3@2-ATP-Cu has a surface area of 242 m2 g-1 and a total pore volume of 55.72 cm3 g-1. In synthesizing 5-substituted 1H-tetrazoles, Fe3O4@SiO2@SBA-3@2-ATP-Cu shows superior yields in short reaction times at 120 °C. This catalyst also showed high thermal stability and recyclability at least for 4 runs without apparent loss of efficiency.

Tables of spectral lines and atlases of spectra for atomic emission, atomic absorption and atomic fluorescence analysis. Bibliographic index

An illustrated bibliographic index of books with tables of spectral lines and atlases of spectra used in practical atomic emission, atomic absorption and atomic fluorescence analyzes has been compiled. The time range covers the period from the emergence of these analytical methods to the present. The index presents the most significant publications for practical work, published in various countries. For each book and atlas, a full bibliographic description and a brief summary of the publication are provided. Most books and atlases in the index are accompanied by illustrations of covers or title pages, as well as email addresses or identifiers that make it easy and quick to find the publication on the Internet. The index is intended for the practical activities of analysts specializing in the field of atomic spectral analysis.

Ecological and geochemical features of mercury load on the territory of south of Western Siberia

Relevance. The need to study contribution of biogenic factors to migration of elements and response of ecological and geochemical system to natural and technogenic situation, which makes it possible to identify the presence of biogeochemical anomalies. Aim. To determine ecological and geochemical features of mercury load in the south of Western Siberia (Tomsk region, Kemerovo region, Altai Territory) according to research (leaves of aspen (Populus tremula L., family Salicaceae)). Objects. Aspen leaves, widely used to analyze the biogeochemical cycle of chemical elements and their migration in the "soil–plant" system, reflect the elemental composition of growing environment and can act as a biogeoindicator for biogeochemical studies. Methods. Sampling of aspen leaves, drying at room temperature, grinding, atomic absorption analysis of mercury on an RA-915M analyzer with the PIRO-915+ attachment (pyrolysis method). The application program STATISTICA 12 was used to process the data analysis and calculate eco-geochemical indicators: concentration factor, enrichment factor, bioaccumulation factor, concentration clarke. Results. The article presents original data on Hg gross concentration in aspen leaves in Tomsk, Kemerovo regions and Altai Territory. The authors have revealed the features of pollutant accumulation depending on the area of growth, geography and orography of the territory, geochemical features of the study areas, and the influence of anthropogenic factors. Calculations of the main geo-environmental indicators of the mercury load were made. The calculation results indicate that the concentrations are higher than the background, the Clarke of the noosphere, and the average for the dry matter of terrestrial plants. The presence of the element in the form available to plants was revealed in the substrate, as evidenced by the results of calculating the bioaccumulation coefficient. Geographically, Hg accumulation in aspen leaves in the south of Western Siberia is associated with the prevailing wind direction and the impact of anthropogenic sources.

Changes in the level of trace elements in the rat brain after exposure to low doses of cadmium

Cadmium is one of the most common toxic elements. Due to its great chemical similarity to calcium, copper and zinc, it can replace them. Food is the main route of cadmium intake into the human body. There are very few studies on the effect of low doses of cadmium on the metabolism of trace elements, so it is of interest to study the effects of exposure to low levels of cadmium in brain tissues.
 The study aims to evaluate the accumulation of cadmium in the brain of experimental animals and its effect on the level of trace elements.
 We have divided the animals into four groups (n=10): the first group served as a control, groups two, three and four, received one, ten and 100 micrograms of cadmium per kg of body weight (Cd1, Cd10, Cd100), respectively, for 30, 60 and 90 days. The researchers injected cadmium chloride solution daily through a gastric tube. The content of cadmium, calcium, copper and zinc in the brain was assessed using atomic absorption analysis.
 The results of this study showed that cadmium chloride intoxication did not lead to metal accumulation in the brain in the Cd1 and Cd10 groups, and the value of cadmium concentration in the Cd100 group did not depend on the time of exposure. The researchers have observed statistically significant changes in zinc and copper concentrations after three months of exposure to cadmium. The zinc content increased depending on the dose, and the copper content decreased.
 Exposure to cadmium for three months in small doses does not lead to significant accumulation in the brain, but causes an imbalance of essential elements such as calcium, zinc and copper.
 Ethics. The study was conducted in accordance with the European Convention for the Protection of Vertebrate Animals Used for Experiments or Other Scientific Purposes (ETS No. 123), Directive 2010/63/EC of the European Parliament and of the Council of the European Union dated 09/22/2010 on the protection of animals used for scientific purposes and approved by the Bioethical Commission of the Ufa Research Institute of Occupational Medicine and Human Ecology.

Synthesis, Characterization and Breast Anti-cancer Activity of Iron(II), Cobalt(II), Nickel(II) and Copper(II) Complexes with a Hexadentate Schiff Base Ligand Derived from 2,5-Dihydroxy-1,4-benzoquinone with 5-Amino-2-methylphenol

The complexes of Fe(II), Co(II), Ni(II), and Cu(II) Schiff base ligand derived from 2,5-dihydroxy-1,4-benzoquinone and 5-amino-2-methylphenol were synthesized. The ligand was synthesized by the reaction between the mentioned ketone and amine in 1:2 molar ratio, respectively. The four metal complexes were synthesized by refluxing the ligand with the related metal(II) chloride salts. The synthesized compounds were characterized using FTIR spectroscopy, UV-visible, 1H-NMR, conductivity, atomic absorption, magnetic susceptibility, and thermogravimetric analysis. According to the results, the chelation between metals and ligand occurs with the imine groups and the deprotonated hydroxyl groups of 2,5-dihydroxy-1,4-benzoquinone and 5-amino-2-methylphenol in the ligand. The conductivity test of the four complexes shows the non-electrolytic nature of them. The magnetic susceptibility values of Fe(II), Co(II), Ni(II), and Cu(II) complexes are 4.20, 4.11, 2.97, and 2.34 B.M, respectively. The thermogravimetric and atomic absorption analyses suggest the general chemical formula for the complexes is [M2(L)(H2O)6]. In addition, the ligand and one of its metal complexes (Co(II) complex) were examined against breast cancer cells, and they gave the IC50 of 101.24 and 129.2 µg/mL, respectively. This result suggests that Co(II) complex is a better anti-cancer agent in comparison with the ligand.

Biogeochemical and microscopic studies of soil and Phragmites australis (Cav.) Trin. ex Steud. plants affected by coal mine dumps.

Developed areas of the coal industry are subjected to long-term anthropogenic impacts from the input and accumulation of overburdened coal material, containing potentially toxic heavy metals and metalloids (HMM). For the first time, comprehensive studies of soils and plants in the territory of the Donetsk coal basin were carried out using X-ray fluorescence, atomic absorption analysis, and electron microscopy. The observed changes in the soil redox conditions were characterized by a high sulfur content, and formations of new microphases of S-containing compounds: FeS2, PbFe6(SO4)4(OH)12, ZnSO4·nH2O, revealed the presence of technogenic salinization, increased Сorg content, and low pH contents. Exceedances of soil maximum permissible concentrations of Pb, Zn, Cu, and As in areas affected by coal dumps were apparent. As a consequence of long-term transformation of the environment with changes in properties and chemical pollution, a phytotoxic effect was revealed in Phragmites australis (Cav.) Trin. ex Steud, accompanied by changes in ultrastructural and organization features of roots and leaves such as increases in root diameters and thickness of leaf blades. The changes in the ultrastructure of cell organelles: a violation of the grana formation process, an increase in the number of plastoglobules, a decrease in the number of mitochondrial cristae, and a reduction in the electron density of the matrix in peroxisomes were also observed. The accumulation of large electron-dense inclusions and membrane fragments in cell vacuoles was observed. Such ultrastructural changes may indicate the existence of a P. australis ecotype due to its long-term adaptation to the disturbed environment.

CATALYTIC HYDROGENATION OF CO IN THE PRESENCE OF LIGNIN-BASED CATALYSTS OBTAINED BY HYDROTHERMAL SYNTHESIS

The work is concerned with the development of a new type of iron-containing catalyst (Ct) based on lignin for the hydrogenation of carbon monoxide. Catalytic systems were obtained by hydrothermal synthesis and studied using a set of physicochemical methods (Fourier Transform IR spectroscopy, Raman spectroscopy, low-temperature nitrogen adsorption, elemental analysis, atomic absorption analysis, X-ray phase analysis, X-ray photoelectron spectroscopy, transmission electron microscopy). Brunauer-Emmett-Teller (BET) surface area analysis, elemental analysis, atomic absorption analysis, X-ray fluorescence (XRF), transmission electron microscopy (TEM). It is shown that the formed catalysts are fine-grained, non-pyrophoric, non-hygroscopic, black powders. The catalytic systems are determined to exhibit high activity in carbon monoxide hydrogenation: the conversion is close to 100%, the productivity with respect to С5+ hydrocarbons reaches 131.6 g/(kg Ct•h).

Redox State and Biogenic Elements in Osteoporosis with Different Localization

The redox state of the human body is the result of a complex influence of enzymes, metabolites, biogenic elements, and endogenous lifestyle factors. With age, unfavorable changes occur and degenerative and pathogenic processes are unlocked, various diseases appear, such as osteoporosis. In the present work, the radical scavenging activity (RSA%) and the blood serum conclusions of copper and magnesium were investigated in patients with osteoporosis of the hip, as well as in patients with osteoporosis of the lumbar spine. 66 menopausal and postmenopausal women aged 63.41±7.81 were investigated - newly diagnosed with osteoporosis and controls. Exclusion criteria were as follows: diabetes, endocrine and liver disease; intake of estrogenic and biogenic elements. Bone mineral density (BMD) was measured in all patients using dual-energy X-ray absorptiometry (DEXA). Patients with T-Score ≤ -2.5 were divided into two groups – with osteoporosis of the hip and with osteoporosis of the lumbar spine. A control group with T-Score > -1.0 was formed. Serum RSA% was established using the experimental method for determining antioxidants ABTS decolonization assay. Serum copper and magnesium levels were determined using atomic absorption analysis. According to the RSA% indicator, we obtained the following values: 73.30 ± 9.84 in the group with lumbar vertebrae osteoporosis; 68.87 ± 13.26 in the hip osteoporosis group; 55.67 ± 1.37 in the control group. When monitoring the radical scavenging activity, depending on the localization of the disease, we detected higher values in patients with osteoporosis of the lumbar spine. Serum copper and magnesium concentrations of all patients were elevated relative to the controls, but there was no statistical difference between groups with different disease localization. Patients with osteoporosis were found to have a higher protective antioxidant capacity in response to increased free-radical processes in the body and cellular metabolic disorders.

Study of the basic laws of dissolution of gold and copper in solutions with an ultra-low concentration of sodium cyanide

The work sets out to study the basic physicochemical dissolution patterns of gold, copper, and natural copper-containing minerals (chalcopyrite, bornite and azurite) in solutions with an ultra-low concentration of sodium cyanide (from 0.102∙10-3 to 4.08∙10-3 mol/L). The influence of various factors on the rate of dissolution of Au and Cu in solutions with ultra-low NaCN concentrations was studied by the rotating disk method; for natural copper minerals, the powder diffraction method was used. The concentration of gold and copper in solutions was determined by atomic absorption analysis. The chemical composition of the studied copper minerals was determined using the X-ray phase method, while the specific surface of the minerals was detected using a laser granulometer. The process of gold dissolution is shown to proceed in both diffusion and kinetic regions. In the diffusion region, the rate constant was 0.334∙10-6 L∙cm-2∙s-1/2∙rad-1/2; in the kinetic region – 0.919∙10-6 L∙cm-2∙s-1/2. The calculated value of the apparent activation energy for the diffusion region was 22.5 kJ/mol; for the kinetic region – 40.1 kJ/mol. The addition of glycine to a solution with an ultra-low concentration of sodium cyanide is shown to increase the specific dissolution rate of gold by 1.2 times: from 0.692∙10-9 to 0.82∙10-9 mol/cm2∙s. The process of copper dissolution is shown to take place in the diffusion r egion. The rate constant was 0.496∙ 10-6 L∙cm-2∙s-1/2∙rad-1/2 at an activation energy of 17.0 kJ/mol. With a fractional supply of sodium cyanide, the dissolution rate of copper minerals is reduced by 10–30% compared to a single load. The calculated apparent activation energy values for chalcopyrite, bornite, and azurite were 22.03, 24.2, and 24.1 kJ/mol, respectively. Thus, the use of ultra-low concentrations of NaCN in the process of cyanidation of gold and copper has a positive effect, which can be used i n the processing of gold-copper raw materials to significantly reduce the consumption of sodium cyanide.

Inorganic compounds of sunflower stems

This paper presents the results of studying the inorganic components of sunflower stems. The test objects are the extracts obtained at different pH values of the medium and ash samples before and after treatment of stems with water, acid, and alkali. The results show that the nature of the extractant has a negligible effect on the yield of extractive substances from the crushed stems. According to atomic absorption analysis, the main ions in extracts obtained in different media are potassium, calcium, magnesium, and sodium ions. The mass fraction of ash after treatment of stems with solutions at different pH values varies from 0.5 to 5.2%. The lowest ash yield is characterized by a sample of stems after acid extraction. According to energy dispersive X-ray fluorescence spectroscopy, all ash samples contain mainly K, Ca, Mg, and P compounds. The ash components of the core and outer part of the stem were also studied in comparison with the original sample. The ash content of the stem core (9.3%) is higher than that of the outer shell (7.4%). The IR spectroscopy shows that the nature of band splitting in the IR spectra of the ash samples practically does not depend on the stem part and the pretreatment of raw materials at different pH values. Absorption bands characteristic of carbonates and silicates are observed in the IR spectra of the stem ash. According to X-ray diffraction analysis, the studied ash samples are in a crystalline state.

Catalytic Hydrogenation of Anthracene on Binary (Bimetallic) Composite Catalysts

The catalytic activity of the binary composite catalysts of Fe2O3-CoO/CaA and Fe2O3-CoO/ZSM-5 was studied. They were obtained by impregnation of CaA and ZSM-5 zeolites with aqueous solutions of sulfates of iron (FeSO4·7H2O) and cobalt (CoSO4·7H2O). The total metal content was no more than 5%. Then, oxidizing burning at 720 °C for 60 min was performed to produce the metal oxides. It was found that the obtained Fe-Co/CaA catalyst contains iron and cobalt as CoFe2O4 compound, and the Fe-Co/ZSM-5 catalyst includes CoFe2O4 and CoFe. The phase composition of the obtained catalysts was detected by the X-ray diffraction analysis. The surface morphology was investigated by the electron microscopy. The elemental composition of the obtained catalysts was determined by energy dispersive spectroscopy with mapping and inductively coupled plasma atomic emission spectroscopy. The atomic absorption analysis by the IR-spectroscopy showed the shifts of absorption bands in the infrared spectra of the pure zeolites and with added Fe and Co. The catalytic hydrogenation of anthracene was performed to determine the catalytic properties of the obtained catalysts. It is one of the most common model compounds applied to investigate the efficiency of catalytic systems. The result of hydrogenation found that conversion of anthracene at 400 °C, initial pressure of 6 MPa and duration of 60 min using the Fe-Co/CaA catalytic system equaled to ~87%. However, hydrogenation products equaled to ~84%. Anthracene conversion using the Fe-Co/ZSM-5 catalytic system and the same conditions was ~91%; among them, hydrogenated derivatives were ~71%. The proposed method is characterized by its simple execution. The obtained catalysts are be slightly inferior to platinum and rhodium catalysts in the catalytic activity.

SORPTION PROPERTIES OF OXIDIZED AND NON-OXIDIZED ACTIVATED CARBON FOR COPPER(II) IONS

The problem of obtaining effective sorption materials is relevant in connection with the growing volumes of industrial wastewater and the development of individual technologies for their purification, including sorption methods. Activated carbon has established itself as a unique sorbent with a high sorption capacity for compounds of various nature. Modification of its surface, its oxidation leads to an increase in adsorption activity. The aim of this work is to compare the sorption properties of oxidized and non-oxidized activated carbon with respect to copper(II) ions. The concentration of Cu(II) ions in the solution was determined by atomic absorption analysis on an MGA-915 spectrometer. The degree of coal oxidation was characterized by the value of the static exchange capacity. Studies on the model synthetic nitrogen-containing carbon SKN showed the presence of different amounts of oxygen-containing surface functional groups: weakly acidic (lactonic) ‒COO‒; strongly acidic (carboxylic) ‒COOH; phenolic ‒OH. It is shown that without access to oxygen, the mechanisms of interaction of activated carbon of different oxidation states with Cu(II) ions are different: when weakly oxidized carbon is used, reductive sorption occurs, and if highly oxidized carbon serves as a sorbent, ion exchange occurs. It was found that for SKN coal with a low oxygen content, the boundary sorption of Cu(II) ions in a deaerated medium is about 40 mg/g; in the presence of oxygen, it decreases to 6 mg/g. An increase in the proportion of carboxyl and phenolic groups leads to an increase in the sorption of Cu(II) ions. Reductive sorption of copper(II) from aerated solutions is thermodynamically prohibited. It is recommended to use additional oxidation of coal to increase the content of PFG and the sorption capacity of the sorbent. For the extraction of copper(II) from aqueous technological solutions, carbon materials with a sufficient amount of oxygen-containing functional groups of various nature are most effective.

Mathematical modelling of the manganese level in the muscle tissue of cattle

The results of determining the most effective model for predicting the level of manganese in the muscle tissue of Hereford cattle for in vivo assessment of the elemental status of animals by low invasive methods are presented. The experiment was carried out using hematological and biochemical blood tests and atomic absorption analysis of the muscle tissue of cattle. The data obtained are used to fit the regression model using the least square method. Skeletal muscle samples weighing 100 g from the diaphragm muscle of the Hereford cattle bred in the southern part of Western Siberia in the conditions of industrial complex were taken for analysis. Manganese concentration in tissues was assessed by atomic absorption analysis on an MGA-1000 spectrometer. The content of erythrocytes, leukocytes, and hemoglobin was determined on an automatic hematology analyzer PCE-90VET. Protein, albumin, globulin, urea, uric acid, and cholesterol levels were determined by photometric methods on a Photometer-5010 semi-automatic biochemical analyzer. The effects of regression models were calculated using the least square method. Selection of the best model for efficiency and accuracy of model estimation was based on a comprehensive assessment of the values of internal and external quality criteria. Statistically significant associations ( p < 0.05) were found between the dependent and independent variables. Within the pool of predictors, correlation ( p < 0.05) was observed. As a result of model fitting, an optimal regression equation including two indicators (erythrocyte sedimentation rate and globulin level) for predicting manganese levels in bovine muscle tissue was obtained. There are no signs of multicollinearity between the main effects of the model, which confirms the values of the variance inflation factor 1.2. The resulting model satisfies the necessary assumptions about the residuals. The distributions of the model residuals fall within the confidence intervals of the normal distribution curve. The autocorrelation coefficient was 0.039 ( p > 0.05), indicating the independence of the residuals. The resulting model can be used for in vivo assessment of manganese concentration in bovine muscle tissue.