Journal of Chemistry and Technologies

NATURAL ALUMINOSILICATES MODIFIED WITH ARENESULFONIC ACID FRAGMENTS AS CATALYSTS FOR ACETALIZATION OF GLYCEROL WITH CYCLOHEXANONE

2024-05-24T13:30:10+03:00

The kinetics of the reaction of glycerol with cyclohexanone in the presence of natural aluminosilicates of the domestic deposit (bentonite, clinoptilolite and trepel) modified with fragments of arenesulfonic acid were studied. The influence of the mass fraction of the catalyst, the reaction temperature and the molar ratio of the reagents on glycerol conversion was determined. It was found that in the presence of bentonite and trepel, unlike clinoptilolite, regardless of the influence of these factors, the glycerol conversion reaches ~100 %. The main product of the reaction is the five-membered cyclic ketal 1.4-dioxaspiro[4,5]decane-2-methanol with a selectivity of 99 % (determined on gas chromatograph Shimadzu GC-2030, Japan). The adsorption and acidic characteristics of the catalysts (pore size, surface area, Brønsted and Lewis acid centers) were studied and the influence of these characteristics on their catalytic properties was compared. It was established that the activity of the catalyst is due to a larger surface area and pore structure. Using the method of «double inverse values» (Lineweaver-Burk plot method), the features of the reaction were investigated, the Michaelis constants and maximum reaction rates and the concentration order of glycerol were determined. A possible reaction mechanism under conditions of heterogeneous acid catalysis is proposed. It is shown that the formation of the cyclohexanone-catalyst complex at the same rate is common to the three samples of catalysts and the subsequent «route» of the reaction differs depending on the concentration order of glycerol.

STUDY ON TNT TOXIC EFFECTS ON THE FUNCTIONAL STATE OF HYDROBIONTS IN THE MODEL CONTAMINATED WATER POND

2024-08-20T17:53:49+03:00

TNT (2,4,6-trinitrotoluene) and its derivatives make a significant contribution to the pollution of the water environment caused by hostilities in Ukraine, but the effects of TNT on hydrobionts have been little studied. In a model experiment, the effect of TNT in concentrations of 10 –75 mg/L on the mortality rate of Daphnia magna crustaceans was observed during 96 hours, and LD₅₀ = 41.8 mg/L was calculated. Impact of TNT on Carassius gibelio fish metabolic processes and red blood cells characteristics were studied during chronic (21 days at a dose of 5 mg/L) and acute (eight hours at a dose of 35 mg/L) experiments. A sharp increase in lipid peroxidation and glutathione S-transferase activity were recorded in the blood and spleen of Carassius gibelio during the chronic TNT action indicating the state of power oxidative stress and detoxification mechanisms activation. Both chronic and acute exposure to TNT caused an increase in the destructive changes in red blood cells of Carassius gibelio as compared to control, including size and shape variation, decreased hemoglobin content, nuclear shift, and cell division disruption. Cytoplasmic vacuolization in fish erythrocytes was detected under the influence of both TNT concentrations, while karyolysis only under acute exposure. The obtained data testify to the severe pathological consequences of 2,4,6-trinitrotoluene impact on the viability and functional state of aquatic organisms under the model conditions and dictate the need to conduct similar studies in the natural polluted aquatic ecosystems to identify ways of their restoration.

SYNTHESIS N-ALKOXY-1-(DIMETHOXYPHOSPHORYLOXY)BENZIMIDATES FROM N-ALKOXY-N-CHLOROBENZAMIDES

2024-05-21T17:20:32+03:00

Aim. To synthesize of N-alkoxy-1-(dimethoxyphosphoryloxy)benzimidates from the interaction of N-alkoxy-N-chlorobenzamides with trimethylphosphite. To investigate N-alkoxy-1-(dimethoxyphosphoryloxy)-benzimidates structure using the XRD study. Methods. Mass spectrometry, ¹H, ³¹P and ¹³C NMR spectroscopy, XRD study. Results. This study explores the reaction of N-alkoxy-N-chlorobenzamides with trimethylphosphite in ether resulting in the formation N-alkoxy-1-(dimethoxyphosphoryloxy)benzimidates. The obtained benzimidates are identified as the products of the nucleophilic substitution at nitrogen followed by an unusual N–O-migration of dimethoxyphosphoryl group. This reaction presents an original synthetic pathway to the N-alkoxy-1-phosphoryloxy imidates. In this research the possibility of the N-alkoxy-N-chlorobenzamides interaction with P-nucleophiles has been proved. The structure of N-alkoxy-1-(dimethoxyphosphoryloxy)benzimidates has been confirmed by the ¹H, ³¹P and ¹³C NMR spectra, mass spectra and XRD study. The XRD study of N-methoxy-1-(dimethoxyphosphoryloxy)-4-nitrobenzimidate has demonstrated that this compound is Z-isomer, and 4-nitrophenyl moiety and N-methoxy group are in a trans position towards to the C=N double bond. The coplanarity of the aromatic ring and the π-system of the C=N double bond is evident from the XRD data. Conclusions. As the result of our study the feasibility of N-alkoxy-1-(phosphoryloxy)benzimidates formation through the interaction of N-alkoxy-N-chlorobenzamides with trialkylphosphites has been elucidated. This outcome holds significant value for a better understanding of the synthetic importance of N-alkoxy-N-chlorobenzamides. The structural elucidation of Z-N-alkoxy-1-(dimethoxyphosphoryloxy)benzimidates has been done. A novel kind of the intramolecular N–O-migration of the phosphoryl group has established.

CONCEPTUALLY NEW MODEL OF GAS CHROMATOGRAPHY

2024-07-15T12:59:43+03:00

The paper describes a mathematical model of gas chromatography in terms of a set concentration waves passing through an adsorption column. An analytical solution is derived for the passage of concentration eigenwaves through the entire adsorption column. This makes it possible to find analytical solutions for an arbitrarily shaped concentration signal passing through the adsorption column. To do this, it is necessary to decompose the input concentration signal into a set of adsorption column eigenwaves and to obtain an analytical solution for each of the concentration eigenwaves at the exit of that column. All of the concentration eigenwave solutions are then combined. This is the solution for passing an arbitrary concentration signal through the adsorption column. This approach is suitable for any periodic adsorption process and allows for the variable concentration of components at the entrance to the adsorption layer. The wave approach to the analysis of chromatographic column processes provides an explanation for the empirical Van Deemter equations used in the practice of gas chromatography.

IMPROVEMENT OF THE THERMODYNAMIC CYCLE OF SINGLE-STAGE STEAM COMPRESSOR REFRIGERATORS

2024-10-10T14:06:51+03:00

The most common device used by mankind are refrigerators. Their number on the planet Earth is significantly inferior to the number of gadgets, but significantly exceeds the number of no less common cars, the main device of which, most often, are internal combustion engines. They, producing mechanical/electrical energy, pollute the Earth's atmosphere with carcinogenic gases and heat, and refrigeration plants, using this energy, pollute the atmosphere with heat. The efficiency of both the direct (energy) cycle and the reverse (refrigeration) cycle depends on the thermodynamic cycle on which they are built. Therefore, several improvements to the thermodynamic cycle of single-stage refrigerating machines are proposed: from the simplest to the most complex, respectively, from less to more efficient. The performed comparative calculations showed that the excess of the main efficiency indicators of the refrigeration cycle with limited regenerative heat exchange over the indicators of the simplest basic cycle (without surface supercooling of the liquefied refrigerant and superheating of saturated steam) do not exceed 6 %. Exceeding similar indicators of the cycle with maximum (limit) regenerative isobaric steam overheating and polytropic process of its compression over the indicators of the cycle with limited regenerative heat exchange reach tens of percent. At the same time, exceeding the indicators of a similar cycle, but with isochoric regenerative steam overheating, reach 100 %.

BEHAVIOUR OF ERYING-POWELL FLUID + NANOFLUID PARTICLES FLOW PAST A VERTICAL CONE IN THE PRESENCE OF MHD, SUCTION/INJECTION, HEAT AND MASS TRANSFER

2024-06-21T21:32:58+03:00

This study investigates the flow and heat and mass transfer characteristics of a nanofluid containing Erying-Powell fluid particles over a vertical cone in the presence of magnetic field, convective boundary condition and suction/injection effects. By using appropriate similarity transformations, the controlling non-linear partial differential equations (PDEs) are converted into ordinary differential equations (ODEs). The finite element method is then used to numerically solve the resultant system of ODEs. In any flow shape, the approach may be used to offer an approximate solution to various fluid rheology problems. Graphs are used to show how different important factors affect the velocity, temperature, and concentration profiles. For vertical cone shape, the skin-friction coefficient, heat transfer rate, and mass transfer rate are also calculated and shown in tables. Finally, the graphs and tables present a comparative study of the vertical cone results. Therefore, in any flow shape, the approach may be used to offer an approximate solution to various fluid rheology problems.

CONVECTIVE INSTABILITY IN POROUS MEDIA: IMPACT OF CHEMICAL REACTION ON MAXWELL-CATTANEO COUPLE-STRESS FERROMAGNETIC FLUIDS

2024-07-23T06:47:00+03:00

The current study analyzes the initiation of convection in a Maxwell-Cattaneo couple-stress ferrofluid within a porous layer, considering the effects of a chemical reaction. Small perturbations are applied to the fluid under the assumption of a zero-order energy release chemical reaction. The system is cooled from the upper layer while maintaining a steady temperature at the lower boundary. We employed linear stability analysis and determined Rayleigh number using the Galerkin Method (GM). This study emphasizes the influence of magnetic, chemical, Maxwell-Cattaneo, and couple-stress parameters on the initiation of ferro-convection. The findings indicate that both magnetic and chemical reaction parameters hasten the initiation of ferro-convection, while the porous medium and couple-stress parameters have a stabilizing effect. Notably, it is demonstrated that the destabilizing effects of chemical reactions and magnetic stresses can be effectively regulated in the presence of couple-stresses. The solutions provide insights into the potential application of ferromagnetic fluids for controlling efficient heat transfer mechanisms.

ATOMIC-ABSORPTION DETERMINATION OF COBALT IN TABLE SALT AND BRINES

2024-01-27T23:17:24+02:00

The extraction of cobalt in the form of diethyldithiocarbamate with methyl isobutyl ketone and chloroform from sodium chloride solutions was investigated. It was found that the interfering effect of sodium chloride begins at 50 g/dm³ when using methyl isobutyl ketone, and at 90 g/dm³ when using chloroform. It is shown that fulvic acids in concentrations above 12.0 mg/dm3 underestimate the results of cobalt determination, which makes quantitative determination impossible without the destruction of soluble organic compounds. It is proposed to use ultrasound with a frequency of 18–44 kHz and an intensity of ≥ 5 W/cm2 for at least 60 s to destroy soluble organic substances of cobalt. It was found that when using the extraction system sodium diethyldithiocarbamate – methyl isobutyl ketone, the quantification limit of cobalt determination is 0.90 mg/kg, which is insufficient for the analysis of real objects of table salt. When using the extraction system sodium diethyldithiocarbamate – chloroform, the quantification limit of cobalt determination is 0.04 mg/kg, which is insufficient for the determination of cobalt in vacuum evaporated table salt. The influence of surfactant concentrations on the analytical signal value in the atomic absorption determination of cobalt was studied. It is shown that the maximum sensitivity of cobalt determination is achieved when using aqueous solutions of Triton X-100 (ω = 5 %). In this case, the sensitivity of cobalt determination increases by 1.53 times. A method for the determination of cobalt in table salt and brines has been developed. The limit of detection of cobalt is 0.026 mg/kg.

BIOACTIVE COMPOUNDS EXTRACTED FROM THE HERB SPERANSKIA TUBERCULATA (BUNGE) BAILL

2024-05-31T14:01:08+03:00

Aim. Identification of bioactive compounds in preparations extracted from the herb Speranskia tuberculata using two different solvents and comparison of the effects of the extracts on human cancer cells of four different lines. Methods. Crude extracts were extracted using ethyl acetate or petroleum ether, followed by distillation, drying and preparation of working solutions based on dimethyl sulfoxide in the 12.5–75 μg/mL concentration range. MTT tests were used to determine the effect of drug concentrations on the viability of cancer cells of four commercially available lines: A549 (lung adenocarcinoma), HEPG2 (hepatocellular carcinoma of the liver), A375 (malignant melanoma) and HELA (pancreatic carcinoma). The tandem liquid chromatography-mass spectroscopy (LC/MS) method was used to identify the main compounds and compare the composition of both extracts. Results. The developed preparations reduced the viability of all 4 types of cancer cells. Ethyl acetate extracts are always more effective than petroleum ether extracts. IC₅₀ of ethyl acetate extract varied between 49–53 μg/mL for all cell lines. Approximately 100–200 compounds have been identified, and their number in petroleum ether extracts is roughly twice as high. Concentrations of 11 compounds significantly increased when switching from extraction with petroleum ether to ethyl acetate. The potential biological activity of identified compounds was analysed based on literature data. Conclusions. The studied preparations reduced the viability of various human cancer cells. Preparations extracted with ethyl acetate were more effective against all types of cells. Hundreds of compounds were identified in the extracts; some anticancer effects were discussed.

TECHNOLOGICAL RECOMMENDATIONS FOR THE PRODUCTION OF HYDROXYLAMMONIUM NITRATE

2024-05-30T19:57:16+03:00

The article presents the results of a comparative analysis of possible methods for obtaining a promising highly effective component for liquid, paste and solid “green” rocket fuels - hydroxylammonium nitrate (NH₃OH)NO₃ (HAN), which is not only safer, but also more efficient and environmentally friendly, since during its combustion mainly non-toxic gases such as water vapor, molecular nitrogen and carbon dioxide are released. The technology for obtaining the target product HAN by a simple exchange reaction of salts of hydroxylammonium sulfate and metal nitrate with the formation of the target product and an insoluble salt, metal sulfate, as a by-product has been studied. The feasibility of using this reaction as an accessible, cheap, non-toxic and non-carcinogenic raw material component is shown, ensuring high efficiency of the technological process due to low energy costs when drying HAN solutions, low yield of the by-product (calcium sulfate) and the possibility of its regeneration into the original calcium nitrate at high yield and purity of the target product.

RESEARCH OF COMMON OAK ACORNS USE FOR ALTERNATE SOLID FUEL PRODUCTION

2024-06-10T10:18:46+03:00

The article presents the experimental studies results of solid fuel production from fruits of common oak (Quercus robur). The calorific value, ash content, and moisture content of the initial plant material and the briquetted solid fuel samples were studied. The value of the highest calorific value for unformed raw materials is ~18163 kJ/kg, and for briquettes ~17428 kJ/kg. The data obtained indicate the prospects of using the common oak (Quercus robur) acorns as a raw material for the production of alternative solid fuels. The value of ash content for unformed raw material is ~0.93 % wt., and for briquettes ~1.22 % wt. The moisture content of all obtained briquetted samples was <1% wt. The data obtained indicate the prospects of using acorns of Quercus robur as a raw material to produce alternative solid fuels, since the parameters are close to existing European standards. The use of alternative solid fuel from acorns can improve the environmental situation by replacing traditional fuel resources and may be one of the ways to rationally use renewable natural raw materials.

THE POTENTIAL OF USING SPENT COFFEE GROUNDS IN THE TECHNOLOGIES OF FUNCTIONAL FOOD PRODUCTS. REVIEW

2024-08-10T16:33:12+03:00

Analytical review was conducted on information provided in 336 articles, books, laws, patents, and Internet publications included in the Scopus, Web of Science, PubMed, and Google Scholar databases using a wide range of search terms, including spent coffee grounds, nutritional value, biologically active compounds, food products, functional properties, consumer health, therapeutic effects. The growth of global coffee consumption and the mass production of spent coffee grounds (SCG), which contain a large number of valuable organic compounds, are a powerful antioxidant and have a positive effect on human health, led to the need for a comprehensive study of the properties of SCG and technologies for its use in food production. The work carried out an analytical review of the scientific literature, summarized the available information on the chemical and mineral composition of SKG, the content of amino acids, carbohydrates, non-protein nitrogenous compounds, caffeine, lipids, minerals and phenolic compounds, dietary fibers, other biologically active substances, which can be effectively used in various industries food industry. Data on the functional properties of SCG and its antioxidant potential, porosity, granulometric composition of SCG, microbiological safety of SCG are summarized, which allows positioning this product as a raw material for providing desired functional properties to food products. Examples of the use of SCG in the technologies of functional products are given. The impact of the use of some SCG biologically active compounds on human health has been analyzed, which makes it possible to reasonably use SCG in the technologies of various functional products with powerful therapeutic effects and a positive impact on the health of consumers.

STUDY OF MASS TRANSFER AND DIFFUSION PROCESSES OF SUCROSE INTO APPLE FRUIT PARTICLES

2024-05-04T20:25:13+03:00

In this study, we designed a setup for blanching and saturating apple fruit particles with sucrose using a bubbling mode of sugar syrup with inert gas. For the saturation process, a sugar syrup was prepared at a temperature of 70 °C and a concentration of 60 % Brix. Based on photomicrographs of blanched fruit sections, we determined the average diameter and total length of channels between blanched apple cells to ascertain the particle's surface porosity, which was found to be 0.162 m²/m². According to the established mechanism for the saturation process, we justified the physical essence of saturation processes in the external and internal diffusion regions. We demonstrated that irregular saturation exists in the external diffusion region at the beginning of the process and saturation occurs during the period of constant velocity. In the internal diffusion region, there is a period of decreasing saturation velocity. We proved that effective diffusion coefficients depend on both the hydrodynamic conditions of the process and the saturation region. In the external diffusion region, the coefficient of effective diffusion is 100–200 times larger than in the internal diffusion region. We proposed to generalize the saturation process separately for the external and internal diffusion regions. Based on the generalization of experimental data, we derived analytical dependencies of sucrose concentration change in apple fruit particles over time for the external and internal diffusion regions. These dependencies enable the theoretical calculation of the amount of sucrose transferring into apple fruit particles in the internal and external diffusion regions. Additionally, we derived dimensional equations in the article, which enable the calculation of the mass transfer coefficient for laminar, turbulent, and transitional regimes of bubbling syrup with inert gas. Using these dimensional equations, the amount of sucrose transferring from the syrup into apple fruit particles via mass transfer can be determined.

NOVEL METHODS OF SPINEL FERRITES PRODUCTION: MINI-REVIEW

2024-07-31T18:57:07+03:00

Spinel ferrites as a type of inorganic compounds have attracted the interest of scientists since their discovery in the last century until now. Spinel ferrites have become one of the best materials for various applications such as catalysts, adsorbents, gas sensors, lithium battery fillers, information storage systems, magnetic fluids, microwave absorbers, etc. The popularity of these ferrites is due to the ability to regulate their specific properties, such as coercive force, permeability, resistivity, and saturation magnetization, by changing their chemical composition and production technologies. In the review, a comparative analysis of various compositions of spinel ferrites, the structure of spinel ferrites, and possible applications was carried out. The classification of methods of obtaining was carried out. Liquid-phase methods can be considered more technologically feasible. When comparing hydrothermal, sonochemical, and sol-gel synthesis methods, it was found that the hydrothermal process makes it possible to adjust the size, shape, monodispersity, and crystallinity. The newest technologies for obtaining ferrites are also considered in detail; plasma, and ultrasonic. Their features are described.

DEVELOPMENT OF RESOURCE-SAVING TECHNOLOGY OF DYEING COTTON FABRICS BY REACTIVE DYES WITH REUSE OF TREATED WASTEWATER FROM DYEING AND FINISHING PRODUCTION AND CREATION OF A BASIC TECHNOLOGICAL SCHEME

2024-03-06T18:58:27+02:00

Consumption of water resources of the textile industry and the generation of large amounts of wastewater negative impact on the environmental ecosystem. The development of resource-saving technologies with the reuse of wastewater treated by adsorption method as a secondary resource in fabric dyeing technology is relevant. The work presents the results of the wastewater reuse treated with a natural zeolite sorbent during the cotton fabric Coarse calico (art. 3399) coloring with reactive dyes: Reactive Blue CB-RF, Reactive Red S-matrix, and Reactive Yellow S-3R. It was practically determined that using purified wastewater in the dyeing cotton fabric technology ensures the fabric coloring intensity 96–99 % compared to the standard (100 %). The obtained color’s stability is at the 4–5 points according to the «Gray standards scale». A series of experiments resulted in the possibility of using the doubly purified wastewater for dyeing cotton fabric with Reactive Blue CB-RF and Reactive Red S-matrix dyes to get a hue within 96 %. The color difference of all examined fabric samples (DE < 2) (when comparing between reference and dyed samples). Thus, the principle diagram of dyeing cotton fabric with reactive dyes and the repeated use of wastewater purified by the adsorption method has been developed. Dyeing according to this scheme has been tested in the production conditions of the Private Joint Stock Company Cherkasy Silk Plant (PJSC CSP) (Cherkasy, Ukraine). The expense of water treatment is calculated by comparing the costs of the water softening process and cleaning wastewater with a zeolite sorbent for its reuse. Cost savings of 10%. The spectrophotometric method was used in the work. The dyeing stability was determined according to Ukraine’s current state and international ISO standards. The Python programming language, engineering, and scientific data visualization libraries Matplotlib and Seaborn were used to visualize the experimental data.

WATER PURIFICATION FROM NITRITE BY THE ENHANCED ULTRAFILTRATION METHOD

2024-03-07T12:06:41+02:00

Commercial polyethersulfone membranes were modified to hydrophilize the surface and improve their transport properties for the nitrite removal process. The nitrites removal method from aqueous solutions is based on their ability to form complex due to binding with amino groups of the water-soluble polymer polyethyleneimine (PEI) in an acidic medium. The complex was separated using the modified membrane in the process of enhanced ultrafiltration. The surface of polyethersulfone membranes was modified using dopamine and polyacrylic acid in order to obtain a charged membrane surface, increase the water permeability coefficient, and improve transport properties. Modification conditions were established as the concentration of dopamine solution 10 mg/ml, pH = 8, T = 298 K, duration of modification 20 h, concentration of polyacrylic acid 0.5 wt.%, T = 298 K, duration of modification 2 h in the presence of EDAC. The effectiveness of the modification, the presence of new functional groups, and the change in surface morphology as a result of the modification were confirmed by infrared spectroscopy, scanning electron microscopy, and atomic force microscopy. The changes in the zeta potential of the membrane surface before and after modification were evaluated. The modification of the membranes leads to an increase in the mass transfer coefficient by 1.65 times and the water permeability coefficient by 1.2 times. The effect of pH, PEI concentration, and the presence of chlorides and sulfates on the process of nitrite extraction from solutions during ultrafiltration was studied. The optimal conditions for nitrite binding were determined as a pH value of 4; 0.5 wt.% concentration of PEI; and reaction time of 60 min. The ultrafiltration experiments of unmodified and modified PES020 commercial membranes were carried out. The productivity of modified membranes is higher than unmodified ones by 20–60 %, which compensates for a slight decrease in the retention coefficient in the process of nitrite removal. The retention coefficient of nitrites by this method is at least 70 %, which allows the effective use of this hybrid technology to remove nitrites from water in high concentrations.

BUCKWHEAT HUSK BIOCHAR: PREPARATION AND STUDY OF ACID-BASE AND ION-EXCHANGE PROPERTIES

2024-06-15T20:48:17+03:00

Ukraine is one of the world's leading producers of buckwheat grain, so it is very important to address the issue of including its processing waste in the production cycle. Buckwheat husk is a promising raw material for biochar production. The aim of the study is to obtain biochar as an additive during food waste composting and to characterise its acid-base and ion-exchange properties. The nature of the potentiometric titration curves of biochar is determined by the additive contribution of all ionised groups of biochar and allows us to classify the studied products as ion exchangers of polyfunctional type. It has been shown that, possessing the properties of ampholytes, biochars in the composting process not only act as acceptors of metal ions, but also function as a soft regulator of pH. The number of groups with the ability to exchange anions ranges from 0.1 (biochar-500) to 1.2 (biochar-MX). The groups with the highest pKa values in the range of biochars studied were found in biochar-500 (pK 7.5), biochar-MX (pK - 7.3) and biochar-300 (pKb 7.0). Other anion-exchange groups have pKb from 4.9 to 6.3 meq/g, which characterises them as weakly basic.

SIMULATION OF THE APPLICATION OF POLYMER COMPOSITE MATERIALS WITH FUNGICIDAL ACTION FOR THE PREVENTION AND TREATMENT OF ONYCHOMYCOSIS

2024-06-10T11:42:10+03:00

The object of research is the process of forming the properties of polymer composite materials with fungicidal properties in the production of medical products. In this work, the problem of effective polymer composite materials with fungicidal properties, which were specially developed to protect the nail from onychomycosis pathogens, was solved. The obtained results give grounds for asserting that the developed polymer composite materials have pronounced fungicidal properties against the causative agents of onychomycosis. Thanks to the optimal composition, the developed polymer materials have the ability to diffuse into the thickness of the nail. It was established that the membrane of bull hooves is the most similar in properties and chemical composition to the human nail and can be used as a model of the human nail in the study of the fungicidal activity of polymers, as well as the determination of the diffusion of active substances in the thickness of the nail. Pronounced diffusion of active substances into the composition of the nail is explained by the presence of urea in the formulation. Also, the effectiveness of the developed polymer materials is influenced by the fact that cation active surfactants, which were not previously used in antifungal agents, were used as active substances. It is shown that almost all the proposed variants of the polymer composite material with fungicidal action are effective against onychomycosis pathogens, except for the variants that contain polyhexamethylenebiguanide hydrochloride as an active substance. The presented results can be useful in the development of polymer composite materials with fungicidal properties for the prevention and treatment of onychomycosis. The practical application of these results is possible in the production of medical products.

ITHE INFLUENCE OF POLYETHYLENETEREPHTHALATE SOLID-SATE POLYCONDENSATION ON IT CRYSTALLIZATION AND MOLECULAR WEIGHT INCREASE

2024-06-10T13:04:14+03:00

This work provides information about the current understanding of polyethylene terephthalate solid-state polycondensation. It presents overall concepts about the mechanism’s polyethylene terephthalate solid-state polycondensation due to it transesterification and esterification reactions under time-temperature dependence. By analyzing a wide range of literature sources, it was found that decreasing the dimensions of polyethylene terephthalate granules/flakes occurs to increase a molecular weight and decrease a degree of crystalinity intense then by using a standard size raw. It was shown that conducting a polyethylene terephthalate solid-state polycondensation under 210 ˚C during 8 h allow to increase it molecular weight more than in 3 times. It has been shown that the increased content of polyethylene terephthalate oligomer derivates with carboxyl group can sighnifilcally increase it solid-state polycondensation quality, but it ratio oligomers with carboxyl and hydroxyl group must be around 2 : 1, correspondly. According to shown data content of diethylene glycol and acetaldehyde can sighnifilcally slow down a polyethylene terephthalate solid-state polycondensation rate.

RECYCLING OF WC-Ni SCRAP TO OBTAIN TUNGSTEN CARBIDE

2024-08-12T17:01:35+03:00

The paper is devoted to the relevant issue of recycling scrap of the strategic WC-Ni alloy used in the production of armor-piercing shells. The recycling of tungsten and nickel carbide eliminates the problem of shortage and high cost of these components. This paper investigates the effect of the concentration of hydrochloric acid and iron (III) chloride in the leaching solution on the extent of nickel leaching from cemented tungsten carbide. It was found that an increase in the concentration of both components leads to an increase in the process rate. It has been shown that the addition of iron (III) chloride to the acid leaching solution leads to a fivefold increase in the process rate. It has been established that the activation energy of the leaching process in a solution of 4.5 mol/L chloride acid is 50.5 kJ/mol. The activation energy of leaching in a solution containing 4.5 mol/L hydrochloric acid and 2 mol/L iron (III) chloride is 17.9 kJ/mol. When switching from an acid leach solution to a solution containing a mixture of acid and iron (III) chloride, the process moves from the kinetic to the diffusion region. To accelerate leaching under conditions of diffusion limitations, it is proposed to increase the efficiency of surface renewal of raw material pieces by selecting the size and rotation frequency of the grinding drum. It has been shown that the dependence of the leaching degree on the drum rotation frequency passes through a maximum. Increasing the diameter of the drum increases the leaching degree. A new method for leaching a WС-Ni composite to obtain high-quality tungsten carbide powder has been proposed. The process intensification is achieved by organizing leaching under self-grinding conditions with continuous mechanical renewal of the surface that is in contact with the leaching solution.

RHEOLOGICAL CHARACTERISTICS OF ENGOBE COATINGS FOR CERAMIC BRICKS

2024-04-14T23:35:27+03:00

This work discusses the rheological features of engobe coatings for ceramic brick. With the correct choice of rheological parameters, the engobe coating is well matched to the ceramic base andallows to improve the aesthetic and operational properties of the brick. The requirements for the rheological parameters of engobe suspensions are formulated. This will help to avoid such defects as cracking and chipping of the coating, exposure of the product surface, formation of craters and specks. The influence of the mineralogical and particle size distribution of suspensions on their sedimentation resistance has been determined. The suspensions containing at least 70 wt.% of particles up to 10 µm have high sedimentation resistance. At the same time, the content of fractions with a size of 10-60 µm can reach up to 30 wt% without signs of suspension stratification. These can be achieved with a clay content of at least 65 wt%. A graphical model has been developed that reflects the simultaneous effect of clay, water and deflocculant (rheotane) on the fluidity of engobe suspensions. This model allows egulate the rheology of engobe suspensions when one or more factors change. To achieve a fluidity engobe suspension containing 65 wt% clay, its moisture content should be 43-43.5 wt% and the amount of rheotane should be 0.21 wt%. With such parameters, the suspension has high sedimentation resistance, a fluidity of 14-17 s, good coating ability and high adhesive strength of the coating. After firing, a coating with a thickness of 140-180 microns, with a Mohs hardness of more than 7, and no signs of any defects, was obtained on the surface of ceramic brick samples. The research results can be applied to the development of engobes and glazes in the production of ceramic bricks and tiles.

THE DEGRADATION OF D-GLUCOSE IN ACIDIC AQUEOUS SOLUTION

2024-05-31T12:26:27+03:00

The objective of this work was to estimate glucose degradation products (GDPs) in model system D-glucose/H⁺ based on the changes in the pH values, absorption of ultraviolet (UV) light and integral intensities of carbonyl absorption (ν 1740–1710 cm^-1) by Raman spectroscopy. Spectrophotometric, pH-metric and Raman spectroscopy methods were used to elucidate mechanism of both glucose degradation and transformation of GDPs in the model D-glucose solutions after desired time and temperature of heating. Common features for all the tested solutions after heating were reduce in pH values and increase in UV absorbance at λ_max 225 nm (absorbance of 3,4-DGE) and in the carbonyl region λ_max 280-285 nm (absorbance of 5-HMF). This indicated that these intermediates had been formed during heating. Their stability increases with a decrease in initial pH values. By Raman and UV spectroscopy methods temperature zones were determined in which certain processes of transformation of D-glucose were seen. It was demonstrated that in the temperature interval at 80–95 °C at all pH values, formation of 3,4-DGE accelerated while the their transformation into 5-HMF slowed down. It was shown that the formation of unsaturated carbonyl-containing compounds (3,4-DGE), as starting intermediates for further transformations were slowed down at pH 3, which indicates a certain stability of D-glucose under these conditions.

JUSTIFICATION OF TECHNOLOGY OF SAUSAGES FOR HERODIETIC PURPOSE

2024-08-02T22:46:24+03:00

The development of food technologies to ensure adequate nutrition for the elderly is a priority concept for the development of the food industry. Sausages made from poultry meat are an important component of the diet of the elderly population. Expanding the range of sausages for herodietic purpose by using non-traditional raw materials of plant origin as a source of polyunsaturated fatty acids and dietary fibers is an urgent task in the meat processing industry. Purpose. Development of the technology of sausages for herodietic purpose using white flax seeds, hemp seed flour, psyllium, olive oil and sea salt. Methods. To evaluate the quality of the developed technology of sausages for herodietic purpose and comparative characteristics with the control, generally accepted methods of determining the chemical and fatty acid composition were used. Results. It was established that white flax seeds, hemp seed flour, psyllium, olive oil and sea salt are promising raw materials for use in the technology of sausages for herodietic purpose. According to the results of organoleptic quality indicators, it was established that sausages of the experimental composition are characterized by high organoleptic quality indicators. An increased mass fraction of dietary fibers by 2.02 % was established in the experimental sample compared to the control sample. The use of olive oil and white flax seeds in the technology of sausages made it possible to obtain a finished product of herodietic purpose with an increased content of omega-3 and omega-6 by 0.579 % and 0.783 %, respectively, compared to the control. According to the results of the study, the possibility of using white flax seeds, hemp seed flour, psyllium, olive oil and sea salt in the technology of sausages for herodietic purpose was proven, which allows to expand the range of functional food.

CRAFT TECHNOLOGIES OF MARINATING SEMI-FINISHED MEAT OF WILD ANIMALS – THE POTENTIAL OF THE MARKET OF ORGANIC PRODUCTS IN UKRAINE

2024-07-31T21:09:55+03:00

Modern approaches to the development of high-quality pickled game semi-finished products are based on a deep understanding of the chemical and biochemical processes that occur during pickling. The use of vegetable ingredients with a high content of organic acids, such as kiwi, in the technology of marinating game meat allows to significantly improve the structural, mechanical and taste qualities of the finished products. Studies have shown that optimal results are achieved when marinating wild boar meat for 24–27 hours using a marinade containing 20–30 % kiwifruit. This concentration is able to ensure the maximum quality and profitability of meat semi-finished products, as indicated by the results of the product yield study after pickling, heat treatment and organoleptic evaluation. The conducted structural and mechanical studies testify to the effectiveness of the developed marinades for improving the texture and juiciness of game meat, as well as emphasizing its unique flavor and aroma profile. It has been studied that the use of fermented pickles from cucumbers and cabbage as marinades for small pieces of semi-finished products from wild boar meat leads to high yields of finished products after heat treatment, which emphasizes their economic suitability for commercial production. Conducted research on the content of essential amino acids in the developed products showed a high balance of marinated semi-finished products from wild boar meat, and proved that a successful selection of components for marinating meat can positively affect the biological value of finished products. Thus, modern pickling methods, including the use of natural enzymes and organic acids, make it possible to create high-quality, safe and economically competitive pickled game semi-finished products. This opens up new opportunities for producers of meat products, contributing to the expansion of the assortment and satisfaction of the growing needs of consumers for healthy and organoleptically high-quality food.

FATTY ACID COMPOSITION OF THE GERODIETETIC PRODUCT FOR ENTERAL NUTRIOTION

2024-06-02T16:48:58+03:00

Lipids are one of the main nutrients determining nutritional value. The fatty acid composition of the developed gerodietetic product’s for enteral nutrition lipids and its biological effectiveness were researched. The determination of the lipids content was carried out by gravimetric method, Folch’s method was applied for their extraction. Fatty acids composition was analysed by gas chromatography method. Identification of fatty acids composition was carried out by comparing the obtained mass spectra with standard ones, their content was calculated by the area of the corresponding peaks. The coefficient of lipids biological significance was calculated as the ratio of eicosapentaenoic and docosahexaenoic acid (DHA) polyunsaturated fatty acids (PUFAs) sum to the mass fraction of total lipids. Based on the conducted research it was found lipids content in the developed product is 11.82±0.13 mass%. PUFAs dominate among them (44.85 mass%). The ratio of polyunsaturated, monounsaturated and saturated fatty acids is 1.00 : 0.52 : 0.67. Linoleic acid predominates on the quantitative composition of product’s fatty acids (22.19 mass%). The content of omega-3 fatty acids is 11.84 % of total lipids. The ratio of omega-3 to omega-6 fatty acids is 1.00 : 2.07, corresponds to the norms recommended in emergencies – 2.0 : 1 – 4.0 : 1. The content of omega-3 fatty acids is11.84 mass%. The ratio of omega-3 to omega-6 fatty acids is 2.07 : 1 and corresponds to the norms recommended for people in in emergencies – 2.0 : 1 – 4.0 : 1.The estimated biological significance of the developed product’s lipids is 40.4 %. The research results provide an opportunity to state that the developed gerodietetic product’s for enteral nutrition fatty acid composition is characterized by rather high nutritional value. It was experimentally confirmed that the developed product is characterized by sufficiently high content of PUFAs, in particular linoleic, α-linolenic, EPA, DHA.

EXTRACTION OF NON-FERROUS METALS FROM AQUEOUS AMMONIUM SOLUTIONS

2024-08-05T17:39:11+03:00

The work is devoted to the extraction of cadmium from ammonia aqueous solutions. The interaction of cadmium with 2-hydroxy-5-alkylbenzylethylenediamine in a wide pH range was studied. The composition of the extracted compounds was also determined. It has been shown that the state of cadmium in ammonia solutions depends on the pH value of the medium, as well as on the concentration of ammonium salt ions. It was found that cadmium in the reactions carried out is in amine forms – [Cd(NH₃)₄]²⁺. In this case, the extractant coordinates with the cadmium ion through the oxygen atoms of the phenolic OH group and the amine nitrogen group. This is confirmed by the fact that cadmium interacts with the reagent as a result of the exchange of the proton of the phenolic OH group and coordination by molecules of the NH group can be provided by the results of an IR spectroscopic study of the reagent and the extracted complex in CCl₄, taken in the range of 700-4000 cm^-1, characteristic of the appearance of ν-vibrations of hydroxyl and NH bonds in the molecules of the extracted compound. The IR spectra of the reagent and the extracted cadmium compound show that the characteristic absorption band of the OH group in the phenol molecule at a wavelength of 3590 cm^-1 sharply decreases, which indicates the replacement of the hydroxyl group proton with the extracted metal ion and the formation of a Cd–O bond. In addition, the absorption band of the NH bond at 1640 cm^-1 is shift into the short-wavelength region of the spectrum in the complex, which also indicates the participation of the NH group in the formation of the complex. These analyzes helped establish that indeed the cadmium ion in complex compounds is hydrogen bonded to molecules and forms a tetrahedral geometry.

QUANTUM-MECHANICAL METHODOLOGY FOR DETERMINING THE TEMPERATURE DEPENDENCE OF CONTACT ANGLE IN MELT–SOLID METAL SYSTEMS

2024-08-16T11:14:20+03:00

Aim. In order to determine the composite materials’ manufacturing process parameters, it is necessary to evaluate the stability of their structural components and determine the contact angle of wetting of the filler with the molten binder at the infiltration temperature. The development of a theoretical method for determining the dependence of the contact angle of wetting on temperature in melt – solid metal systems makes it possible to reduce the volume of experimental studies. Methods. The paper presents a quantum mechanical methodology for calculating the binding energy of interacting substances, as well as an experimental study of the dependence of the contact angle on temperature for tin – steel systems. The methodology is based on the calculation of the binding energy between atoms of interacting substances using density functional theory. Results. The calculations show an anomalous behavior of contact angle values for the tin–steel system with increasing temperatures. It means that, when the temperature increases, the values of the contact angle initially become lower, and later, in the temperature range of 450-510 °C, an increase in the contact angle is observed. The obtained theoretical and experimental data correlate well with each other. Conclusions. The appearance of extreme regions in the experimental and theoretical temperature dependences is associated with the thermal expansion of interatomic distances in the crystal lattice. The obtained theoretical and experimental data correlate well with each other and base on the thermal expansion of interatomic distances in the crystal lattice.

SYNTHESIS, CRYSTAL STRUCTURE, THERMAL STABILITY AND HIRSHFELD SURFACE ANALYSIS OF AZAMETALLOCROWN COPPER(II) COMPOUNDS WITH 4-IODOPYRAZOLE

2024-08-06T14:26:08+03:00

The reaction of copper(II) chloride and copper(II) bromide with 4-iodopyrazole (HIpz or C₃H₃IN₂) in the presence of copper powder in acetonitrile leads to the formation of the corresponding trinuclear copper(II) pyrazolates, [Cu₃(OH)(C₃H₂IN₂)₃Cl₂ ·2CH₃CN]₂ (1), and [Cu₃(OH)(C₃H₂IN₂)₃Br₂]_n (2), respectively. Both complexes maintain the [Cu₃(μ₃-OH)(μ-Ipz)₃]²⁺ core, but they exhibit relevant differences in their molecular structures, as well as in their supramolecular arrangements. The crystal structure of complex 1 comprises trinuclear 9-azaMC-3 units linked by chlorine anions into dimers and arranged into polymeric chains through hydrogen bonds formed between the hydrogen atoms of the OH group and the Cl⁻ anions of adjacent fragments. The crystal structure of complex 2 is built up from the parallel packing of supramolecular chains running along the c-axis direction. Within each chain, the trinuclear metallacrown-like complex subunits are interconnected by bridging bromine atoms. Analysis of the geometry of the polyhedra revealed that the coordination polyhedron geometry of the pentacoordinated copper(II) ions in both structures is intermediate between trigonal bipyramidal and square pyramidal. The process of thermal degradation of the synthesized complexes with metallocrown structure was studied with the help of differential thermal analysis and thermogravimetry. Hirshfeld surfaces analysis was performed to investigate the intermolecular atomic contacts in the crystal structure of the title complexes.

PHASE EQUILIBRIA IN THE La2O3-Lu2O3-Ho2O3 SYSTEM AT 1500 °С

2024-09-03T13:35:51+03:00

The phase equilibria in the La₂O₃–Lu₂O₃–Ho₂O₃ ternary system at 1500 °C were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM) in the whole concentration range. La₂О₃, Lu₂О₃, and Ho₂О₃ (99.99 %) were used as starting substances. The experimental samples were prepared with a concentration step of 1–5 mol%. The oxides were dissolved in HNO₃ (1 : 1) followed by evaporation of the solutions and decomposition of nitrates at 800 °C for 2 hours. The samples were heat treated at 1500 °C (for 70 h) in air. The phase composition of the test samples studied by X-ray diffraction (XRD, DRON-3), microstructural phase and electron microprobe X–ray (Superprobe-733, JEOL, Japan, Palo Alto, CA) analyses. Solid solutions based on various polymorphic forms of original oxides and ordered LaLuO₃ phase were detected in the system. No new phases were found in the system. The isothermal cross-sections of the La₂O₃–Lu₂O₃–Ho₂O₃phase diagram at 1500 °C are characterized by the presence of four single-phase (A-La₂O₃, B-La₂O₃_,R, C-Lu₂O₃ (Ho₂O₃)), five two-phase (C + R, A + R, B + A, B + R, B + C) and two three-phase ( A + R+ B, B + R + C) regions. Solubility limits are determined and concentration dependences of periods also lattice parameters of the unit cell of phases formed in the system are constructed. The range of homogeneity of solid solutions based on the R-phase extends from 0 to 8 mol% Ho₂O₃ and from ~47 to 54 mol% La₂O₃ at 1500 °C. Lu and Ho oxides form an continuous series of C-REE oxide solid solutions.