Journal of Chemistry and Technologies

PRODUCTS OF THE INTERACTION OF CHROMIUM(VI) WITH SOME DERIVATIVES OF 6,7-DIHYDROXYBENZOPYRILYLIUM SALTS AND THEIR APPLICATION IN CLOUD POINT EXTRACTION

2025-11-04T13:37:18+02:00

The interaction of chromium(VI) with a series of alkyl- and phenyl-substituted salts of 6,7-dihydroxybenzopyrylium was studied. Using spectrophotometric methods, the stoichiometry of the reaction products was established. Based on the data obtained from potentiometric, spectrophotometric, and mass spectrometric studies, a reaction mechanism was proposed. The chemical and analytical characteristics of the reaction products were determined, and it was noted that the most intensely colored analytical forms were those based on perchlorates of 6,7-dihydroxy-2,4-diphenylbenzopyrylium and 6,7-dihydroxy-4-methyl-2-phenylbenzopyrylium. The optimal conditions for micellar-extraction preconcentration of the reaction product of chromium(VI) with 6,7-dihydroxy-4-methyl-2-phenylbenzopyrylium perchlorate were established as follows: 1 vol.% Triton X-100, pH 2.0, 5×10⁻⁴ mol/dm³ of dye, 0.2 mol/dm³ sodium sulfate, and heating for 30 minutes at 70–80 °C. The calibration graph was linear within the concentration range of 0.05–1.7 mg/dm³, with detection and quantification limits of 0.015 and 0.05 mg/dm³, respectively. The developed method was tested on model solutions and samples of mineral waters.

DETERMINATION OF EXPLOSIVE COMPOUNDS IN SOIL BY HPLC-UV METHOD USING MODIFIED QUECHERS SAMPLE PREPARATION

2025-08-06T11:48:17+03:00

The method for analyzing explosives in soil was developed by HPLC-UV employing a modified QuEChERS sample preparation technique. The method of simultaneous determination of fourteen explosives in soil was validated according to the following criteria: specificity, linearity, limits of detection (LOD), limits of quantification (LOQ), accuracy, and precision. The chromatographic conditions for separation and determination of the explosives were optimized during the study. It was established that the most optimal mobile phase for the separation of fourteen explosives is water: formic acid in a ratio of 99.9 : 0.1 (by volume; eluent A) and methanol: formic acid in a ratio of 99.9 : 0,1 (by volume; eluent B). Chromatography was performed in isocratic mode (eluent A/B, 60/40). It was found that the correlation coefficients for fourteen explosives range from 0.998 to 0.999 (R² > 0.995). The limit of detection (LOD) and limit of quantification (LOQ) for explosives range from 0.012 to 0.081 mg/kg and 0.040 to 0.270 mg/kg, respectively. Percent recovery (R, %) in the range from 73.0 to 95.7 % indicates the acceptability of the explosives extraction procedure. The relative standard deviation (RSD, %) of the measurement results under conditions of repeatability ranged from 3.6 to 9.6 %. The obtained data suitability evaluation of method (validation) comply with the requirements of ISO 11916-1:2013 and method 8330A. The determined parameters of the proposed method also meet all the suitability assessment criteria and minimum permissible values according to Commission Decision 2002/657/EC. Therefore, the presented method is suitable for use in chemical analytical laboratories to determine the residual quantities of explosives in soils at the appropriate level.

STUDY OF THE La-Ni-Ce TERNARY SYSTEM ACROSS THE LaNi5-CeNi5, LaNi5-CeNi, AND LaNi-CeNi POLYTHERMAL SECTIONS

2025-07-15T11:48:26+03:00

Intermetallic compounds of transition metals, especially lanthanides, and the new phases based on them attract the attention of researchers as effective adsorbers for hydrogen. Using physicochemical analysis techniques, including Differential Thermal Analysis (DTA), Powder x-ray Diffraction (PXRD) and Scanning Electron Microscope (SEM), the ternary La-Ni-Ce system was investigated across the LaNi₅-CeNi₅, LaNi₅-CeNi, and LaNi-CeNi polythermal quasi-binary sections. The corresponding (T-x) phase diagrams have been constructed for the title system. The phase diagrams are quasi-binary and of the eutectic type. The systems have revealed wide regions of solid solutions based on starting compounds LaNi₅, LaNi, CeNi₅, CeNi. It has been established that the coordinates of the eutectic point formed on the basis of the initial components for the LaNi₅-CeNi₅, LaNi₅-CeNi, and LaNi-CeNi sections are 50 mol% CeNi₅, 1150 °C, 68 mol% CeNi, 650 °C, and 50 mol% CeNi, 620 °C, respectively. The obtained variable-composition phases can be considered as promising materials for hydrogen absorption.

PHASE RELATION IN THE Fe2O3-Gd2O3 SYSTEM AT 1300 AND 1400 °С

2025-08-04T19:23:16+03:00

The phase interaction in the Fe₂O₃–Gd₂O₃ system at 1300 and 1400 °C were studied across the full concentration range using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Samples, prepared in 1–5 mol% composition increments, were obtained by dissolving the oxides in HNO₃ (1 : 1), evaporating the solutions, and decomposing the nitrates at 800 °C for 2 h. The resulting powders were pressed at 10 MPa into 5 mm × 4 mm pellets and heat-treated in air at 1300 °C (300 h) and 1400 °C (100 h). The phase composition was determined using X-ray diffraction (XRD, DRON-3) and microstructural analysis (Superprobe-733, JEOL, Japan; Palo Alto, California, USA). At 1300 and 1400 °C, the isothermal sections of the Fe₂O₃–Gd₂O₃ phase diagram comprise four single-phase regions (B–Gd₂O₃, GdFeO₃(R), Gd₃Fe₅O₁₂, Fe₂O₃) and three two-phase regions (B–Gd₂O₃ + GdFeO₃, GdFeO₃ + Gd₃Fe₅O₁₂, Gd₃Fe₅O₁₂ + Fe₂O₃). The concentration dependence of the unit cell parameters for phases in the studied system was established. In the Fe₂O₃–Gd₂O₃ system at 1300 and 1400 °C, an ordered perovskite-type phase with orthorhombic distortion (GdFeO₃) is formed. Its homogeneity range at both temperatures extends from 48 to 52 mol.% Gd₂O₃.

SYNTHESIS OF NITRIFICATION INHIBITORS BASED ON Mn(II) COORDINATION COMPOUNDS

2025-08-05T14:17:01+03:00

The combination of two effective nitrification inhibitors, such as dicyandiamide (DCD) and 4-amino-1,2,4-triazole (ATC) in manganese coordination compounds can exhibit a synergistic effect in relation to the nitrification process of ammonium nitrogen in the soil. As a result of this effect, the efficiency of nitrogen fertilizer use is predicted to increase. Manganese, as a biometal, after the end of the inhibitor action can be involved in biochemical reactions of crop development. Therefore, the aim of the work was the synthesis of nitrification inhibitors (NIs) based on Mn(II) coordination compounds. A number of studies of the structure, composition and biological activity of the synthesized compounds were carried out. As a result, four substances with a ligand ratio of 4-amino-1,2,4-triazole and dicyandiamide (1 : 1, 2 : 1, 1 : 2, 2 : 2) were obtained. Their solubility in water, aqueous solution of fertilizer UAN-28 and pure KAS-28 was established. Thermal destruction of the studied substances was studied. Infrared spectroscopy proved 1,2-coordination of 4-amino-1,2,4-triazole through nitrogen atoms. The addition of dicyandiamide is carried out through the C≡N functional group. The manganese content in complex compounds was established. The degree of nitrification inhibition and the dynamics of nitrification rate changes were studied in laboratory conditions.

PHASE EQUILIBRIA IN THE HfO2–La2O3–Nd2O3 SYSTEM AT 1500 °С

2025-07-24T12:46:27+03:00

Phase equilibria within the HfO₂–La₂O₃–Nd₂O₃ ternary system (across the 0-100 mol% HfO₂ concentration range) were investigated using X-ray phase analysis and microstructural analysis. Based on the experimental results, an isothermal section of the phase diagram at 1500 °С was constructed. It was established that at this temperature, the HfO₂–La₂O₃–Nd₂O₃ system exhibits three continuous solid solution series: the hexagonal A-Ln₂O₃ type (P6₃/m), the monoclinic M-HfO₂ type (P2₁/c), and an ordered pyrochlore-type phase (Fd3^-m), Ln₂Hf₂O₇. The corresponding homogeneity regions border the biphasic fields (M + Py) and (Py + A), respectively. No new phases were found to form under the investigated conditions. The lattice parameter (a) of the ordered pyrochlore-type phase Ln₂Hf₂O₇ varies linearly: from a = 1.0572 nm for a biphasic sample (A + Py) of composition 2 mol% HfO₂ – 49 mol% La₂O₃ – 49 mol% Nd₂O₃, to a = 1.0696 nm for the solid solution boundary composition, and a = 1.06657 nm for a biphasic sample (Py + M) of composition 65 mol% HfO₂ – 17.5 mol% La₂O₃ – 17.5 mol% Nd₂O₃.

SYNTHESIS, X-RAY CRYSTAL STRUCTURE, SPECTROSCOPIC CHARACTERIZATION AND MALDI MASS SPECTRA, HIRSHFELD SURFACE ANALYSIS OF OCTANUCLEAR AZAMETALLACROWN COPPER(II) COMPLEX WITH 3,5-DIMETHYL-1H-PYRAZOLE, OBTAINED BY OXIDATIVE DISSOLUTION METHOD

2025-09-10T14:57:35+03:00

A novel copper(II) polynuclear complex with deprotonated 3,5-dimethyl-1H-pyrazole of composition
Cu₈(µ₃-O)₂(DMPZ-Н)₈(NCO)₂(OAc)₂·2CH₃OH has been synthesized and isolated in the crystalline state. A variety of techniques were employed to identify and characterize the structure of the complex, including IR spectroscopy, microanalysis, MALDI analysis, and single-crystal X-ray diffraction. It was observed that Cu₈(µ₃-O)₂(DMPZ-Н)₈(NCO)₂(OAc)₂·2CH₃OH had been formed as a result of a multistage process of oxidative dissolution of metallic copper with the participation of air oxygen and ammonium ions. This process results in the accumulation of a sufficient concentration of Cu²⁺ ions in the solution, which contributes to both the formation of the final product and the dissolution of metallic copper through the intermediate generation of Cu⁺ species. These intermediates are subsequently oxidized by atmospheric oxygen to yield divalent copper compounds. The resulting octanuclear complex Cu₈(µ₃-O)₂(DMPZ-Н)₈(NCO)₂(OAc)₂·2CH₃OH is a new inverted 24-azametallocrown-8, due to the implementation of the cyclic interaction (-Cu-N-N-)₈ formed by eight copper ions and eight μ₂-bridge coordinated 3,5-dimethyl-1H-pyrazole anions. A crystallographic 2-fold axis bisects the obtained octanuclear complex on the same two trinuclear fragments Cu2-Cu3-Cu4ⁱ and Cu2ⁱ-Cu3ⁱ-Cu4, which are sequentially linked by deprotonated bidentate-bridging coordinated molecules of 3,5-dimethyl-1H-pyrazoles and bridging μ₃-O^2-, which are the centers of coordination for three copper cations. Tetradentate-bridged cyanate groups additionally assemble the thrinuclear fragments into an octanuclear complex. Hirshfeld surface analysis, complemented by two-dimensional fingerprint plots, was carried out to investigate the intermolecular interactions in the crystal structure. The results revealed dominant H···H contacts (71.7 %) along with notable contributions from H···C/C···H, H···O/O···H and H···N/N···H interactions, confirming that hydrogen bonding plays a significant role in stabilizing the crystal packing.

POLYELECTROLYTE FILMS BASED ON SODIUM ALGINATE AND CHITOSAN: PREPARATION, PHYSICOCHEMICAL PROPERTIES, KINETICS OF CALCIUM PANTOTHENATE RELEASE

2025-06-16T12:51:07+03:00

A forming method based on alginate-chitosan polyelectrolyte complexes was developed, and the physicochemical properties of the resulting films were investigated. Ionic-strength-induced suppression of electrostatic interactions was employed to control complex precipitation during assembly. Films based on alginate-chitosan complex (AC) and its sodium hyaluronate modified version (AСН) were successfully obtained. The morphology of the obtained films was investigated by scanning electron microscopy, atomic force microscopy, and low-temperature nitrogen sorption-desorption. It was established that the films have a porous structure (pore surface area is from 2 to 5 m²/g, pore volume 5–10·10^-3 cm³/g, average pore size 3.5±1 nm). The mean square surface roughness is 345±30 nm. It was found that KBr also plays the role of a pore former in the system. The dependence of the swelling of the obtained polyelectrolyte films was studied at different pH values corresponding to the pH of the skin (5.5), open (7.2), and infected (8.2) wounds. It was found that the swelling of AC films is pH sensitive. Thus, the film swells the most (~ 300 %) in a weakly alkaline environment and the worst (~ 100 %) in a neutral one. The addition of sodium hyaluronate led to the formation of a denser complex, which levelled the pH sensitivity of swelling. Calcium pantothenate was immobilised in the films by adding a solution of drugs to the formation mixture. Infrared spectroscopy has shown that no covalent bonds are formed between calcium pantothenate and the polyelectrolyte complex. Analysis of release profiles has shown that the kinetics of calcium pantothenate release are best described by the Higuchi model, which is typical for diffusion-controlled drug delivery systems. The release process was pH-sensitive and independent of the polyelectrolyte complex. The obtained polyelectrolyte films demonstrate strong potential as matrices for the development of controlled drug delivery systems.

NEW QUATERNARY COMPOUND FeGdSbS4 IN THE FeSb2S4–FeGd2S4 SYSTEM

2025-06-03T10:31:02+03:00

For the first time, the quaternary compound FeGdSbS₄ was studied using various physicochemical methods over a wide temperature range. The study of the FeSb₂S₄–FeGd₂S₄ system revealed that at a ratio of FeSb₂S₄:FeGd₂S₄ = 1:1, the quaternary compound FeGdSbS₄ forms. FeGdSbS₄ melts congruently at 1200 K and has a berthierite-type structure (a = 11.382, b = 13.896, c = 3.614 Å; Z = 4; V = 571.606 Å³, space group Pbam). The specific electrical conductivity of FeGdSbS₄ at room temperature is 2×10⁻⁴ Om⁻¹·m⁻¹. FeGdSbS₄ is an impurity semiconductor. The thermal band gap ΔEg of FeGdSbS₄ is 1.31 eV. Investigation of the magnitude and sign of the thermoelectric power (TEP) and thermal conductivity in the FeSb₂S₄–FeGd₂S₄ system shows that both dependencies reach their maxima at the composition corresponding to FeGdSbS₄. The Seebeck coefficient (α) for FeGdSbS₄ is 1000 mkV/K, and the thermal conductivity is 1.32 Vt/m·K. The FeSb₂S₄–FeGd₂S₄ system is a quasi-binary section characterized by the formation of a quaternary compound FeGdSbS₄, which melts congruently and belongs to the berthierite structural type.

SEPARATION OF NATIVE NANO-DISPERSE CLAY SORBENT SUSPENSION BY FLOCCULATION AND SEDIMENTATION

2025-07-08T10:53:44+03:00

The growth of industrial and agricultural production inevitably leads to an increase in freshwater deficiency, and this is indeed observed on all continents of our planet. The only way to overcome this challenging problem is to develop effective methods for purifying circulating water from dispersed and soluble substances, including heavy metal ions and water-soluble components petroleum products (Toluene, Benzene, Phenol, and similar ones.) It is generally recognised that the simplest, most accessible, and cheapest way to purify water from soluble contaminants is the use of ultrafine clay sorbents. Studies on the process of separating clay suspensions have been conducted using samples of clays mined from deposits in Ukraine. The samples were treated with anionic flocculants. The effectiveness of flocculants, their optimal dose, and the optimal medium shear rate in the flocculator were defined using the device UltraFloc-Tester “UFT-TFS-029”. It was found that, depending on the properties of the clay, the treatment of the clay suspension (3 g/l) for 6 seconds in a flocculator at a medium shear rate of 1000–1500 s^-1 followed by subsequent separation in a flow-through horizontal micro-settler for 55 seconds, allowed to achieve the residual suspension concentration around 0.18–0.42 g/l. Additionally, it has been found that Magnafloc 5250 can be regarded as the most effective and commonly used all-purpose flocculant for the studied clay suspensions.

REGENERATION OF USED TURBINE OILS AND RECOVERY OF THEIR QUALITY PARAMETERS USING ACTIVATED BENTONITE

2025-09-02T11:22:22+03:00

This article covers the problem of regeneration of turbine oils used in the power engineering. The main attention is given to the process of purification and recovery of used Shell Turbo S4 GX46 mineral oil with usage of activated Navbahor bentonite as an adsorbent. The research analyzes the factors of oil degradation during operation (oxidation, contamination, mixing with water), and also studies the adsorption properties of bentonite using SEM (scanning electron microscopy), EDS (energy dispersive X-ray spectroscopy) and physicochemical analysis. The results show that due to the high content of SiO₂ (58.68 %) and Al₂O₃ (15.42 %), bentonite effectively removes contaminants, and the purified oil restores its kinematic viscosity, acid number and thermal stability. Considering the forecasts of global oil consumption, the use of bentonite is recommended as an economically and environmentally effective regeneration method. Gas chromatography-mass spectrometry analysis showed an increase in components such as tetratriacontane (26.53 %) and hexatriacontane (70.56 %) in the purified oil, confirming its improved stability and anti-corrosion properties. From an economic perspective, this method is efficient and gains importance in light of global projections suggesting a 3–4 % growth in oil consumption.

COMPREHENSIVE ANALYSIS OF THE CHEMICAL, AMINO ACID COMPOSITION AND HISTOLOGICAL STRUCTURE OF AFRICAN OSTRICH MEAT

2025-07-02T10:43:43+03:00

The work presents a comprehensive study of the chemical composition, amino acid profile and histological features of Ukrainian-produced African ostrich meat in comparison with traditional types of meat raw materials. Modern methods of chemical analysis were used to determine the content of protein, total fat, cholesterol and nitrogenous extractive compounds - carnosine, anserine, carnitine, creatine and taurine. Structural changes in muscle tissue were studied by histological method using the standard technique of staining sections with Ehrlich hematoxylin and eosin, which provides differentiation of cellular and tissue structures for further analysis. The results of the analysis indicate that ostrich meat is characterized by high biological value of protein: the total content of essential amino acids in it is not inferior to the recommended optimal ratio and in some cases exceeds the indicators of "ideal" protein. The total fat content of ostrich meat was significantly lower compared to chicken, turkey, beef and pork, which makes it an attractive dietary product with a reduced risk of developing cardiovascular diseases. The concentration of cholesterol in ostrich meat is at a level lower than similar indicators of most traditional types of meat, which also emphasizes its beneficial properties. Histological analysis revealed a characteristic fine-fibrous structure of ostrich muscle fibers with a low density of connective tissue layers, which contributes to the tenderness of the texture and ease of digestion. African ostrich meat should be considered as a high-quality dietary product with the prospect of using not only in traditional culinary technologies, but also in the production of functional food additives and ready-made dishes for preventive purposes. In the future, it is advisable to focus on standardizing the conditions for keeping ostriches, improving the technology of cooling and storing meat, as well as on further clinical and dietary studies to confirm its beneficial effects on human health.

COMPARATIVE ASSESSMENT OF MICRO- AND NANOPLASTIC RELEASE FROM POLYPROPYLENE AND POLYCARBONATE BOTTLES UNDER SIMULATED USE CONDITIONS

2025-09-03T15:52:56+03:00

This study provides a comprehensive comparison of polypropylene (PP) and polycarbonate (PC) bottles with respect to their chemical and mechanical stability under simulated conditions of routine consumer use, including thermal and chemical stress. The release of micro- and nanoplastics was systematically evaluated using dynamic light scattering (DLS) and scanning electron microscopy (SEM). SEM analysis revealed noticeable surface degradation, microcrack formation, and material fatigue, particularly in PP samples, indicating progressive structural deterioration. DLS measurements confirmed the presence of a broad particle size distribution ranging from 3.6 to 3777 nm, with high polydispersity indices (PDI > 0.7), reflecting heterogeneous particle release. Overall, PP exhibited a higher tendency to release micro- and nanoplastics, which is attributed to its lower thermal resistance and reduced chemical stability compared to PC. However, an environmental impact assessment using the AGREEMIP framework showed that PP has a comparatively lower overall environmental footprint. In contrast, PC presents higher potential health and environmental risks, primarily due to the possible release of toxic monomers and the hazardous reagents involved in its synthesis.

ANALYSIS OF MODERN METHODS OF LEGUME PROCESSING AND THEIR IMPACT ON THE NUTRITIONAL VALUE AND DIGESTIBILITY OF RAW MATERIALS

2025-05-28T13:05:36+03:00

This review article systematically analyzes and synthesizes current scientific literature on modern innovative methods of legume processing and their impact on nutritional value, functional properties, and sensory characteristics of final products. Key technologies, including fermentation, ultrasonic processing, high-pressure processing, extrusion, microwave and infrared heating, and electromagnetic field treatment, are critically reviewed and compared. Particular attention is focused on synthesizing reported data on the reduction of anti-nutrients, increasing the bioavailability of proteins and trace elements, and improving the texture and taste of legume-based products. This review analyzes the scientific basis and technological principles of each method and highlights literature-reported mechanisms through which they affect the structural and chemical composition of pulses. The synergistic effects of combined processing methods are discussed in the context of improved nutrient retention, reduced energy consumption, and enhanced processing efficiency. The synthesis of the literature indicates that these methods contribute to expanding the use of pulses in the food industry, particularly in the production of high-protein snacks, meat and dairy alternatives, gluten-free products, and functional foods with targeted health benefits. These technologies support sustainable and innovative food systems by increasing the value of pulses as affordable and environmentally friendly protein sources. In addition, special attention is dedicated to integrated processing approaches that combine several advanced methods to achieve high efficiency in improving the nutritional, physicochemical, and sensory properties of pulses. This review identifies the importance of process optimization, scaling-up potential, and the impact of processing conditions on product quality and consumer acceptance. The findings of this review can be used to develop novel food products, optimize production processes, increase supply chain sustainability, and guide further research in plant-based processing technologies. This review emphasizes the strategic role of pulses in supporting global food security and the transition to healthier and more sustainable diets.

CUTTING FOOD PRODUCTS WITH A WATER-POLYMER JET: SCIENTIFIC AND PRACTICAL ASPECTS

2025-10-22T13:11:27+03:00

A scientifically grounded hydrodynamic calculation method for determining the optimal parameters of food product cutting using a water-polymer jet has been developed. This method is based on an established criterion that incorporates the relaxation time of the polymer solution and the longitudinal velocity gradient, which occurs during the flow of the polymer solution through the nozzle of the hydro-cutting head. An analytical expression for the relaxation time of the polymer solution has been derived, linking the experimentally observed relaxation time with the extrapolated relaxation time at zero concentration. The validity of this relationship, which connects the relaxation time of the polymer solution with its concentration, temperature, and characteristic viscosity, is confirmed by experimental data on the concentration dependence of the relaxation time for two fractions of polyethylene oxide in water.The developed method for calculating the optimal parameters of food cutting using a water-polymer jet enabled a significant reduction in the working pressure of the hydro-cutting machine – by 4 to 5 times – through the implementation of a high-efficiency cutting process. Under equal conditions, the cutting depth of frozen pork at –25 °С was increased by 2 to 2.3 times compared to water jet cutting, whereas standard equipment achieved only a 1.85 – fold increase. The experimental prototype of the hydro-cutting machine for food products using a water-polymer jet was 10 times less expensive than industrial-grade equipment. The developed method for calculating the optimal parameters for hydrojet water-polymer cutting has confirmed the practical feasibility and economic efficiency of using a water-polymer jet for cutting food products, particularly for deeply frozen products, by implementing a high-efficiency hydro-cutting process.

CHARACTERIZATION OF LIGNOCELLULOSIC BIOMASS COMPLEX FOR UNLOCKING THE POTENTIAL OF SUSTAINABLE BIOFUEL PRODUCTION

2025-09-15T10:49:18+03:00

The present study investigates the chemical composition and delignification efficiency of various lignocellulosic biomass types as feedstock for bioethanol production. Agricultural residues and dedicated energy crops were identified as the most promising substrates due to their high cellulose (exceeding 40 %) and hemicellulose content (20–28 %), which are crucial for fermentable sugar yield. Non-fibrous biomass with higher lignin content, such as apricot and walnut shells (43–44 % lignin), exhibited structural resistance that hinders the effectiveness of pretreatment. Peracetic acid pretreatment was applied as a selective delignification method, demonstrating significant lignin removal while minimizing polysaccharide degradation. The optimal duration of pretreatment was established to be between 90 and 120 minutes, which provides a balance between preserving substrate yield and maximizing lignin reduction. Despite diffusion limitations in shell biomass, leading to higher residual lignin content, these substrates retained a significant proportion of polysaccharides, highlighting their potential for further use after process optimization. The findings provide critical insights into biomass-specific pretreatment strategies, facilitating enhanced enzymatic hydrolysis and subsequent biochemical conversion to bioethanol.

FLAME-RETARDANT BEHAVIOR OF UREA–METAPHOSPHORIC ACID COMPLEXES ON CELLULOSE-BASED MATERIALS

2025-08-07T13:16:43+03:00

In this study, novel urea metaphosphate complexes were synthesized at 1:1, 1:2, and 1:3 molar ratios using urea and metaphosphoric acid to obtain mono-, di-, and trimetaphosphate derivatives (UMP, UDP, and UTP). The synthesized compounds were comprehensively characterized through FTIR spectroscopy, powder X-ray diffraction (XRD), and elemental analysis, confirming their structural frameworks, protonation levels, and compositional features. Crystallographic analysis revealed distinct variations in unit-cell symmetry and packing as the phosphate chain length increased, indicating the formation of progressively more complex hydrogen-bonding networks. The flame-retardant performance of the complexes was examined using treated cellulose-based substrates, including paper, cardboard, and cotton fabric, in accordance with GOST R 50810-95 and GOST 12.1.004-91 standards. Experimental results demonstrated a clear enhancement in flame-retardant efficiency with increasing phosphate content, with UTP exhibiting the highest thermal stability and char-forming capability. Overall, the findings highlight the potential of urea metaphosphate complexes as multifunctional materials with promising applications in both agrochemistry and fire-protection technologies.

ESSENTIAL OIL OF LAVENDER FLOWERS (LAVANDULA ANGUSTIFOLIA MILL.) FROM LAM DONG, VIETNAM: CHEMICAL COMPOSITION AND BIOLOGICAL ACTIVITIES

2025-08-16T18:28:00+03:00

The current research examines the sensory qualities, key physicochemical parameters, comprehensive chemical profile, and notable bioactivities—particularly its antibacterial and antioxidant potential—of lavender (Lavandula angustifolia Mill.) essential oil. Gas chromatography-mass spectrometry was utilized to evaluate the volatile components of the essential oil extracted from lavender flowers. The results indicated that the primary chemicals responsible for the essential oil's distinctive aroma were linalyl acetate (39.22 %) and β-linalool (24.15 %). Furthermore, the study found that the oil possesses a freezing point below –20 °C. Assessment of the essential oil's biological properties revealed a moderate effectiveness in inhibiting the growth of Bacillus cereus and Escherichia coli, suggesting possible applications in antibacterial formulations. However, its antioxidant efficacy was significantly lower than that of the reference standard, vitamin C, evidenced by an IC₅₀ value of 77.11 mg/mL. By thoroughly examining these characteristics, this study contributes valuable scientific knowledge that can inform quality assessment and explore the broad range of potential applications for lavender essential oil in various industrial sectors.

PVA-CoFe2O4-BIOCHAR COMPOSITES: STRUCTURE AND PROPERTIES

2025-07-25T23:07:01+03:00

PVA-CoFe₂O₄-biochar composites were synthesized by a two-stage combined method. The resulting composites were characterized by X-ray diffraction, scanning electron microscopy, UV-visible absorption spectroscopy, vibrational magnetometry, and vector microwave analysis. The results of electron microscopy show that biochar has a block structure with large pores, so this structure can be used in the creation of composites. The magnetic properties depend on the content of cobalt ferrite in the composite. The results of the study of photocatalytic properties showed that the rate of destruction of methylene blue (MB) is 50–98% after 60 min of UV radiation. It was established that the reaction of photocatalytic decomposition of MB obeys pseudo-first-order kinetics. Among these catalysts, biochar showed the highest rate constant of 0.085 min−1, PVA/CoFe₂O₄-biochar composites – 0.05 min⁻¹.

When studying the absorption of electromagnetic radiation in the radar range from 8 GHz to 12 GHz by PVA/CoFe₂O₄-biochar composites, it was found that with an increase in the ratio of CoFe₂O₄-bichar components to 0.67 wt. parts CoFe₂O₄, the absorption losses of the composite reach –14.15 dB/mm at a frequency of 8 GHz and –12.37 dB at a frequency of 12 GHz.

IMPACT OF BIOTECHNOLOGICAL FACTORS ON THE EFFICIENCY OF CORN MASH FERMENTATION IN THE PRODUCTION OF RECTIFIED ETHYL ALCOHOL

2025-04-11T08:01:27+03:00

The article presents the results of studies on the influence of enzyme preparations, dry yeast, growth activators, and corn grain germs on the synthesis of ethanol and volatile impurities in the production of rectified ethyl alcohol. The research utilized enzyme preparations, dry distiller’s yeast, and activators supplied by leading domestic suppliers. It was established that as the solids content in the mash increased from 24 % to 28 %, the ethanol concentration in the fermentation mash rose by 13–22 % (from 12.4 % to 14.3 % v/v), reaching its highest level when using preparations from LLC “BIOTEST.” At the same time, the content of aldehydes, esters, and methanol in the experimental samples was the lowest. The minimum amount of aldehydes was formed in the fermentation mash with a solids content of 24 %, while the lowest concentration of fusel oils was observed in the wash obtained using preparations from LLC “A-PROFI.” The concentration of methyl alcohol was highest when using preparations from LLC “Novokontakt” and PE “KOUROS.” It was found that removing the grain germ before milling positively affects the qualitative composition of the fermentation mash. Processing raw materials with a lower content of ballast substances reduces the concentration of fusel oils, esters, and ethyl acetate in the fermentation mash, increases ethanol concentration by 7.7–8.9 %, and decreases methanol content by up to 40 %. Further processing of such wash in a distillation-rectification unit allows reducing energy consumption, lowering the production cost of rectified ethyl alcohol, and improving its quality indicators. The use of growth activators during yeast propagation increases ethanol concentration in the wash by 3.8 %, while the content of organic impurities rises insignificantly.

COMPARATIVE STUDIES OF THE PROPERTIES OF BOILED SAUSAGES OF FUNCTIONAL PURPOSE WITH TOMATO POMACE OR THEIR SUBCRITICAL EXTRACTS

2025-07-23T15:40:28+03:00

The development of technologies for functional cooked sausages (CS) involves reducing fat and salt content, eliminating sodium nitrite, and enriching their composition with tomato purée (TP) or their subcritical extracts. The purpose of the work is to investigate the properties of CS made using TP or their subcritical extracts. Methods: subcritical extracts of TP were obtained in a high-pressure reactor RVD-2-500; study of the properties of objects – using generally accepted methods. Results. Replacing 40 % of pork with chicken meat; removing sodium nitrite from the composition of CS, replacing 60–62 % of table salt with a mixture of spices and adding to the recipe composition of TP (in the form of powder – 3 %, 6 %, 9 %) or their subcritical extract (2 %, 4 %, 6 %), with their subsequent organoleptic evaluation allowed us to select samples with the addition of 6 % TP and 4 % TP extract. The improvement of the technology led to the enrichment of CS with dietary fibers, carotenoids (mainly lycopene), made it possible to reduce the hardness of VK by 2.1–8.1 %; improve chewing properties by 1.02–1.07 times; reduce fat content, increase the content of crude fiber, cooking yield and emulsion stability. There was a slight increase in the brightness of CS samples with TР and an increase in red color. The presence of lycopene led to an increase in the antioxidant properties of the samples: after 10 days of storage, the TBARS index for samples with 6 % TР and 4 % TР extract had values of 1.7 and 1.8, and the control sample had 2.3 mg of malondehydrate/kg. Microbiological indicators of all samples met the current requirements. Conclusions: samples with 6% TB and 4 % TР extract were positively perceived by experts and increased the nutritional value and consumer properties of CS.

THE EFFECT OF AERATION ON THE BIOCONVERSION OF CLITORIA TERNATEA L. TEA BY THE CULTURE OF MICROORGANISMS MEDUSOMYCES GISEVII DP-21

2025-01-11T11:10:15+02:00

Traditional kombucha is produced by fermenting an infusion of black or green tea using a symbiotic culture of bacteria and yeast (SCOBY). According to the classification of microorganisms, this culture is called Medusomyces gisevii. It ferments sucrose and other components of the wort, which can serve as the basis for creating new products with original sensory properties beneficial to human health. The article determines the optimal temperature for extracting Clitoria ternatea L. tea leaves for the preparation of kombucha fermented beverage. It was established that the change in the color of the wort during fermentation is caused by an increase in its acidity and a corresponding change in the coloration of the fermented wort. The influence of aeration during fermentation on the appearance of the drinks was analyzed. The effect of dry matter content, particularly sucrose, on the fermentation process was studied. Changes in titratable acidity during the fermentation of wort under different cultivation conditions were determined. The content of acetic, gluconic, glucuronic, pyruvic, malic, citric, and succinic acids in the fermented wort was identified. The organoleptic profile of the drinks was examined, which confirms the feasibility of aerating the wort during fermentation.

A NEW APPROACH TO PROCESSING POLYMINERAL POTASSIUM ORE FROM THE CARPATHIAN REGION

2025-10-06T09:02:39+03:00

Existing technologies for processing polymineral potash ores of the Carpathian region do not ensure the production of high-quality, highly concentrated fertilizers and are also characterized by a low degree of potassium extraction (less than 60 %). Shenitization of ore in dumps allows achieving a higher degree of conversion of sparingly soluble langbeinite and kieserite into readily soluble minerals but it is a long-term process. Therefore, it is proposed to convert sparingly soluble minerals into readily soluble ones from the residue after ore dissolution using reversible salt suspensions. Based on experimental studies, a new technology for the production of chlorine-free potash fertilizers has been developed which includes the conversion of pre-prepared ore with a reversible salt suspension. This technological method and grinding of the residue before conversion can increase the extraction of potassium into the product up to 82 %. The main products of the proposed technology are table salt, potash fertilizers, magnesium chloride (or bischofite). The residue, which contains insoluble components, in particular, polyhalite can be processed into a long-acting, chloride-free, granular potassium fertilizer with trace elements.

SYNTHESIS OF NOVEL N-BENZYL AND RELATED 1H-1,2,3-TRIAZOLE-4-CARBOXAMIDES AND THEIR ANTIBACTERIAL AND ANTIFUNGAL ACTIVITIES

2025-07-25T15:31:52+03:00

A series of novel N-benzyl and related 1H-1,2,3-triazole-4-carboxamides was synthesized and investigated as potential antibacterial and antifungal agents. The new amides were obtained via a convenient synthetic route involving the cyclocondensation of aryl azides with β-ketoesters to form 1H-1,2,3-triazole-4-carboxylic acids, followed by their conversion into amides through the reaction of the corresponding acid chlorides with appropriate amines. A preliminary antimicrobial screening at a concentration of 32 µg/mL was conducted against a panel of bacterial strains, including Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii, as well as fungal pathogens Candida albicans and Cryptococcus neoformans. Several compounds demonstrated selective or broad-spectrum inhibitory activity, with compound 5m showing the most consistent effectiveness across all tested strains. Notable antibacterial activity was observed for compound 5n (20.20 % inhibition of A. baumannii), while compounds 5a (22.35 % inhibition of C. neoformans) and 5h (17.70 % inhibition of C. albicans) exhibited pronounced antifungal activity. Compound 7a showed a promising dual action profile, inhibiting A. baumannii by 21.05 % and C. albicans by 13.20 %. Among all the tested microorganisms, A. baumannii and C. albicans were the most sensitive to the studied compounds. The results indicate that specific structural features of these 1,2,3-triazole-4-carboxamides contribute significantly to their biological activity and highlight their potential as scaffolds for the development of new antimicrobial agents.

NEW HYBRID XANTHENE-PYRYLIUM DYES: SYNTHESIS AND SPECTRAL PROPERTIES

2025-07-17T14:32:22+03:00

In this work we studied the interaction of N'-(4-formyl-2,3-dihydro-1H-xanthen-9-yl)-N,N-dimethylimidoformamide with 2,6-di-tert-butyl-4-methylpyrylium perchlorate and 2-methyl-4,6-diphenylpyrylium tetrafluoroborate in acetic anhydride under various conditions. Thus, when carrying out the reaction with 2,6-di-tert-butyl-4-methylpyrylium perchlorate at 100 °C for 6 h, the corresponding dye is formed with the amidine group replaced by acetyl. In the case of carrying out the reaction with 2-methyl-4,6-diphenylpyrylium tetrafluoroborate at room temperature for 1 h, the dye is formed with the amidine fragment preserved. The absorption spectra of the obtained dyes were recorded in various solvents and the extinction coefficients were calculated. The absorption maximum of 4-{(E)-2-[9-(acetylamino)-2,3-dihydro-1H-xanthen-4-yl]vinyl}-2,6-di-tert-butylpyrylium perchlorate in toluene and chloroform is approximately 675 nm, whereas in water it is hypsochromically shifted to 605 nm. The absorption coefficient of this dye in chloroform is observed to be the highest, with a value that is 5-7 times higher than that in water or toluene. A modification in the polarity of the solvent exerts minimal influence on the absorption maximum of 2-[(E)-2-(9-{[(1E)-(dimethylamino)methylene]amino}-2,3-dihydro-1H-xanthen-4-yl)vinyl]-4,6-diphenylpyrylium tetrafluoroborate, which is situated at approximately 715 nm.

SYNTHESIS OF N,N'-(((HYDRAZINE-1,2-DICARBONOTHIOYL)BIS(AZANEDIYL))BIS(2,2,2-TRICHLOROETHANE-1,1-DIYL))CARBOXAMIDES AND THEIR CYCLISATION INTO N,N'-(((1,3,4-THIADIAZOLE-2,5-DIYL)BIS(AZANEDIYL))BIS(2,2,2-TRICHLOROETHANE-1,1-DIYL))CARBOXAMIDES

2025-09-08T06:12:58+03:00

1,3,4-Thiadiazole derivatives are widely used in science and technology as biologically active compounds, components of polymer and rubber compositions, dyes and varnishes, catalysts, as well as materials for microelectronics and nanotechnology. This work presents the synthesis of new bis-amidoalkylated derivatives of 2,5-diamino-1,3,4-thiadiazole. The preparation of these compounds is based on the reaction of oxidative dehydrosulfonation of N,N'-(((hydrazine-1,2-dicarbonothioyl)bis(azanediyl))bis(2,2,2-trichloroethane-1,1-diyl))carboxamides using a mixture of iodine and triethylamine in DMF. The reaction was carried out at room temperature for two hours. This method yields target products in the range of 63–92 %. The advantage of the method is the absence of the need for expensive or hard-to-find reagents. NMR ¹H and ¹³C spectroscopy confirmed the structure of the synthesized compounds. The ¹H NMR spectra of synthesized 1,3,4-thiadiazoles are distinguished by the presence of doublet signals corresponding to two NH protons observed in the 9.53–6.69 ppm range, along with a doublet of doublets assigned to the CH proton of the alkylamide fragment appearing at 6.77–6.69 ppm. The ¹³C NMR spectra exhibit characteristic resonances of the C=O carbon at 168.8–164.7 ppm and the C=N carbon of the thiadiazole ring at 158.9–158.6 ppm. Furthermore, characteristics signals attributed to the CCl₃_ moiety and the CH carbon of the alkylamide fragment are observed at 101.5–101.2 and 70.0–69.4 ppm respectively.

ELECTROSYNTHESIS OF NI-FE FILMS WITH ENHANCED ELECTROCATALYTIC ACTIVITY FOR HYDROGEN EVOLUTION FROM ALKALINE ELECTROLYTE

2025-10-15T20:33:33+03:00

The work is devoted to the topical issue of creating electrocatalysts for hydrogen evolution from alkaline electrolyte. The rapid development of hydrogen energy using the electrolytic method of hydrogen requires the use of cheap, resource-intensive and highly catalytic cathode materials. The most variable and flexible in control is the electrochemical method of synthesizing electrocatalysts of this type. A very promising material for cathodic hydrogen release is the Ni-Fe alloy. The limiting factor for its use is the high internal stresses that arise during its electrosynthesis. To reduce the internal stresses of Ni-Fe electrocatalyst films, sulfur-containing modifiers sodium allyl sulfonate and sodium saccharinate were used in this work, which were introduced into the methanesulfonate electrolyte of electrodeposition. It was established that increasing the concentration of sodium allyl sulfonate from 30 to 100 mmol/l leads to a decrease in internal stresses from 300 MPa to 100 MPa. The use of sodium saccharinate in a concentration of 0.5 mmol/l to 6 mmol/l contributes to a decrease in internal stresses from 300 MPa to 0 MPa. This effect of modifiers on internal stresses is associated with a change in the alloy structure due to the incorporation of sulfur and hydrocarbon residues of modifiers. It was found that the Ni-Fe alloy obtained in the presence of allyl sulfonate demonstrates high electroactivity, approaching the electroactivity of platinum. This effect is explained by an increase in defects in the crystal lattice and the presence of nickel and iron sulfide particles in the structure of the cathode material. It is recommended to carry out the electrosynthesis of Ni-Fe, as electrocatalysts for hydrogen evolution, from a methanesulfonate electrolyte containing 80–100 mmol/l of sodium allyl sulfonate in the range of current densities from 3 to 7 A/dm².

ELECTRODEPOSITION OF Ni-BASED COMPOSITE COATINGS CONTAINING CERIUM COMPOUNDS FROM A DEEP EUTECTIC SOLVENT AND THEIR ELECTROCATALYTIC PERFORMANCE

2025-08-11T12:49:18+03:00

This work examines the electrodeposition of Ni-based composite coatings containing cerium compounds from a eutectic mixture of choline chloride and urea (reline), a typical deep eutectic solvent. The data reveal that depending on the concentrations of NiCl₂×6H₂O and CeCl₃×7H₂O dissolved in reline, coatings containing up to 49 wt.% cerium, present as embedded CeO₂, can be formed within an electrochemically deposited nanocrystalline nickel matrix. Variation of the Ni(II) and Ce(III) salt concentrations strongly influences the resulting surface morphology. Reaction schemes for the formation of these composite coatings are proposed, and cyclic voltammetry with successive scan cycles was used to identify the potential windows in which the relevant electrochemical reactions occur in reline-based solutions. The deposited coatings were tested as electrocatalysts for water electrolysis in 1 M NaOH. Special attention was paid to the electrocatalytic activity of the Ni-based composite coatings toward the anodic oxidation of urea, a potential alternative to the oxygen evolution reaction in green hydrogen production. Incorporation of CeO₂ into the nickel matrix led to a pronounced enhancement of electrocatalytic activity for hydrogen evolution, oxygen evolution and urea oxidation in alkaline aqueous solution. The proposed composite coatings may find application as multifunctional catalysts for green hydrogen generation. Moreover, adjusting the Ni(II) and Ce(III) concentrations in the deep eutectic solvent-based plating bath enables flexible and controlled tuning of the electrocatalytic behavior of deposited coatings.

MODELING FLOW DYNAMICS OF CHEMICALLY REACTING MAXWELL FLUIDS OVER POROUS STRETCHING SHEETS

2025-07-14T12:57:19+03:00

This study explores the flow dynamics of chemically reacting Maxwell fluids over porous stretching sheets, focusing on the interplay between fluid rheology, chemical kinetics, and porous media effects. It analyzes the influence of the viscoelastic properties of a fluid on momentum and concentration of boundary layers, considering chemical reactions and the permeability of the stretching sheet. The mathematical model accounts for the non-Newtonian nature of the Maxwell fluid, reaction kinetics, and porous medium resistance. Numerical solutions explore the effects of key parameters on velocity, concentration profiles, heat, and mass transfer rates. The findings offer insights into coupled transport phenomena in engineering processes involving non-Newtonian fluids, chemical reactions, and porous media. Dimensionless problems are numerically solved using the Runge-Kutta approach. The study focuses on important engineering parameters that affect velocity, concentration, and temperature profiles. Quantitative values of engineering factors such as skin-friction, Sherwood number, and Nusselt number coefficients are presented, and the results are analyzed using graphics and tabular representations. For program code validation, a numerical comparison with previously released data is provided.

INTEGRATED MULTICRITERIA ANALYSIS OF HYDROGEN AND AMMONIA AS ALTERNATIVE MARINE FUELS IN THE MARITIME TRANSPORT DECARBONIZATION PROCESS

2025-10-22T11:50:39+03:00

In this work, a new method of fuel selection for ships is proposed, taking into account indicators of efficiency, environmental friendliness and safety. First, the characteristics of hydrogen and ammonia as potential substitutes for traditional fuels are analyzed in detail with an emphasis on cost, energy efficiency and technical features of their storage and transportation. Next, with the help of statistical models, the risks of emergency situations were assessed, taking into account random factors for the quantitative determination of the probability of failures under different operating conditions. The next step is to formulate the task of optimal choice of route and type of fuel, combining economic costs and safety requirements. A separate section is devoted to the analysis of the full life cycle of fuel, from production to final consumption, which makes it possible to compare the environmental impact of different options. Based on the obtained results, a generalized index was developed that allows shipowners and operators to make informed decisions during the transition to «green» technologies. Examples of real projects illustrate the practical suitability of the approach and its prospects for fleet modernization in the face of global emissions reduction requirements.