Physicochemical Transformations Research Articles

Long-Term Exposure of Fresh and Aged Nano Zinc Oxide Promotes Hepatocellular Carcinoma Malignancy by Up-Regulating Claudin-2.

Tumor development and progression is a long and complex process influenced by a combination of intrinsic (eg, gene mutation) and extrinsic (eg, environmental pollution) factors. As a detoxification organ, the liver plays an important role in human exposure and response to various environmental pollutants including nanomaterials (NMs). Hepatocellular carcinoma (HCC) is one of the most common malignant tumors and remains a serious threat to human health. Whether NMs promote liver cancer progression remains elusive and assessing long-term exposure to subtoxic doses of nanoparticles (NPs) remains a challenge. In this study, we focused on the promotional effects of nano zinc oxide (nZnO) on the malignant progression of human HCC cells HepG2, especially aged nZnO that has undergone physicochemical transformation. In in vitro experiments, we performed colony forming efficiency, soft agar colony formation, and cell migration/invasion assays on HepG2 cells that had been exposed to a low dose of nZnO (1.5μg/mL) for 3 or 4 months. In in vivo experiments, we subcutaneously inoculated HepG2 cells that had undergone long-term exposure to nZnO for 4 months into BALB/c athymic nude mice and observed tumor formation. ZnCl2 was administered to determine the role of zinc ions. Chronic low-dose exposure to nZnO significantly intensified the malignant progression of HCC cells, whereas aged nZnO may exacerbate the severity of malignant progression. Furthermore, through transcriptome sequencing analysis and in vitro cellular rescue experiments, we demonstrated that the mechanism of nZnO-induced malignant progression of HCC could be linked to the activation of Claudin-2 (CLDN2), one of the components of cellular tight junctions, and the dysregulation of its downstream signaling pathways. Long-term exposure of fresh and aged nZnO promotes hepatocellular carcinoma malignancy by up-regulating CLDN2. The implications of this work can be profound for cancer patients, as the use of various nanoproducts and unintentional exposure to environmentally transformed NMs may unknowingly hasten the progression of their cancers.

QUALITY AND SAFETY PARAMETERS BEFORE AND AFTER PASTEURIZATION OF APPLE JUICE

The research was carried out in September (2023) on the premises of the “Kosovo Agricultural Institute” in the city of Peja. The purpose of this research was to show the influence of pasteurization on the physical, chemical, and organoleptic characteristics of apple juice. During the study, several analyses of the physical, chemical, and sensory parameters of apple juice were carried out. The parameters that have been realized include: °Brix value, Total acidity, Vitamin C, pH and SO2, sensory parameters: aroma, color, taste, and clarity-turbidity. The purpose of this research is the importance of knowing the influence of some parameters on apple juice before and after pasteurization. Pasteurization of apple juice is of great importance due to various factors related to food safety, storage, and consumer health. In the analysis of sensory parameters, the juice before pasteurization had a milder and lighter aroma, had a lighter yellow color, tasted less sweet, less fresh, and had low acidity. Clarity was present but contained some turbidity. In the analysis of sensory parameters, the evaluation of physicochemical parameters and sensory parameters should contribute to valuable knowledge on the physicochemical transformations caused by pasteurization in apple juice. Understanding these changes is very important for maintaining product quality and ensuring customer satisfaction. The study provides a basis for optimizing pasteurization processes to minimize unwanted changes in juice characteristics.

Investigation of the Process of Agglomeration of Phosphorites Using Phosphate-Siliceous Shales and Oil Sludge

Introduction This article aims to discuss the physico-chemical features of the agglomeration process of phosphorus fines using phosphate-siliceous shales and oil sludge. Methods The composition and structure of the starting materials and physico-chemical transformations under thermal influence are studied using IR spectrometry and differential thermal analysis methods. Results The results of IR spectrometric analysis of the phosphate siliceous shales are characterized by intense peaks at 493.78, 547.78, and 678.94 cm-1, corresponding to Ca-O-P compounds. Moreover, the wave oscillations in the region of 837.11-995.27 cm-1 indicate the characteristics of Si-O valence bonds, and in the region of 1114.86-1431 cm-1 depict the characteristics of Si-O-Al compounds. The IR spectrum of oil sludge is characterized by the presence of wave oscillations in the region of 1411.89-2904.80 cm-1 corresponding to petroleum components. Conclusion The differential thermal analysis of the investigated sample of phosphate-siliceous shale does not have intense endo- and exo-effects, and it is characterized by a significant predominance of hydrate compounds of aluminosilicate and carbonate components.

Modifying the Effects around the Well can have an Impact on the Drilling Process

Environmental changes around a well can significantly affect the drilling process. This paper examines the effects of flow rate, bottomhole pressure, sheet permeability, viscosity, pressure gradient and well radius on the drilling process. It is shown that the energy-dynamic instability of the sheet’s near-shiva space, a highly active region in the formation, leads to changes in reservoir rock and fluid properties during the drilling process. These changes include physicochemical transformations such as deposition of asphaltenes, paraffins, and resins, as well as swelling of clay particles, which can disrupt reservoir physical properties and affect hydrocarbon flow. In addition, completion and production techniques and the chemistry of drilling and pressure fluids are particularly critical for low-permeability reservoirs. In this paper, the concept of skin effect is also introduced to assess the impact of process fluids on the bottomhole region, and a new assessment model is proposed. The results of the study are important for improving drilling technology and optimising reservoir development.

Possibilities of producing lightweight aggregates from silica-clay raw material and cellulosic waste

AbstractThe subject of the work is the characterization of lightweight aggregates intended for construction using the example of silica-clay raw material from south-eastern Poland (Dylągówka-Zapady deposit). The primary objective of the research is to assess the possibility of managing the accumulated organic waste, including cellulose pulp. This storage is problematic for processing plants and local government bodies and incurs high costs annually. Therefore, based on the patent (Kukułka et al. Method of producing raw meal, dried clay granules, and fired clay granules and the production line of raw meal, dried clay granules, and baked clay granules. Patent RP no P.429284.), an attempt was made to confirm the assumptions of the technology of fired clay granules, which can be used for zootechnical, agricultural, and construction purposes. The presented work assessed the physicochemical transformations in the clay-silica raw material after adding a significant amount of cellulose waste (10%, 20%, and 30%) in the temperature range of 25–1300 °C were assessed. Thermal methods such as thermodilatometry, Hot-Stage Microscopy with image analysis (IA-HSM) and thermal DSC/TG analysis with gas analysis were used for this purpose. Based on the first method, a temperature range was established in which sintering occurs without an apparent effect of densification. Therefore, the range of 850–950 °C was used to obtain fired granules, which were tested as a material for lightweight aggregates.

Uncovering phytochemicals quantitative evolution in avocado fruit mesocarp during ripening: A targeted LC-MS metabolic exploration of Hass, Fuerte and Bacon varieties

Avocado ripening entails intricate physicochemical transformations resulting in desirable characteristics for consumption; however, its impact on specific metabolites and its cultivar dependence remains largely unexplored. This study employed LC-MS to quantitatively monitor 30 avocado pulp metabolites, including phenolic compounds, amino acids, nucleosides, vitamins, phytohormones, and related compounds, from unripe to overripe stages, in three commercial varieties (Hass, Fuerte, and Bacon). Multivariate statistical analysis revealed significant metabolic variations between cultivars, leading to the identification of potential varietal markers. Most monitored metabolites exhibited dynamic quantitative changes. Although phenolic compounds generally increased during ripening, exceptions such as epicatechin and chlorogenic acid were noted. Amino acids and derivatives displayed a highly cultivar-dependent evolution, with Fuerte demonstrating the highest concentrations and most pronounced fluctuations. In contrast to penstemide, uridine and abscisic acid levels consistently increased during ripening. Several compounds characteristic of the Bacon variety were delineated but require further research for identification and role elucidation.

Employing limestone and calcined clay for preserving the strain-hardening response of PET fiber-reinforced cementitious composites

The degradation of polyethylene terephthalate (PET) fibers in alkaline environments limits their use in strain-hardening cementitious composites (SHCC). Prolonged PET exposure to alkaline environments has a detrimental effect on its mechanical performance, mainly due to the physicochemical transformation caused by alkaline hydrolysis. This study presents a tailored cementitious matrix design containing high amounts of limestone and calcined clay, replacing 75 wt% of Portland cement, to attain and maintain the strain-hardening response of composites incorporating PET fibers as dispersed reinforcement. Analytical and mechanical tests were carried out at different curing ages, ranging from 7 to 60 days, to study the effects of aging on virgin PET fibers, both within the matrix and outside it (in the pore solution). The results showed a pronounced degradation of the PET fibers in the test pore solution at pH 12.5, manifested by a progressive reduction in the load-bearing capacity of the individual fibers with prolonged immersion. Conversely, when the PET fibers were aged in-matrix under laboratory conditions and tested under tension, the performance of the corresponding composites showed resilience to aging, exhibiting reasonable tensile strength and remarkable strain capacities that exceeded 4 %.

Про фундаментальну підготовку фахівців авіаційної та аерокосмічної галузей

The subject of the study is the state of the fundamental training of specialists in aviation, rocket, and space technology. Recently, the processes of expanding and deepening the fundamental training of specialists in the specialized areas of specific higher education institutions have been intensified. Unfortunately, experience of recent years has shown, the priorities rightfully belong to the aviation and aerospace industries, both in the scientific/creative and design/production spheres. Training of the specialists in the field of aerohydrodynamics of aircraft and their components; gas dynamics of the modern aircraft engines of various types, is currently the priority. In addition, both – the problems in aeroelasticity and research in the field of aerodynamic acoustics related to the environmental safety of the operation of aviation equipment are important for the design of the modern aircraft. Moreover, the design of aircraft that overcomes trans- and supersonic flight speed, requires in-depth study of the processes of heat and mass exchange determining physico-chemical transformations, which are also present in the internal gas-dynamic processes of gas-turbodynamic and rocket engines of aircraft. Structure and comparative analysis study of programs and courses for fundamental training of specialists in the aerospace industry at the universities of USA, Canada, Germany, China, as well as in KhAI, Ukraine, are presented. This study provides comparative information about scientific and experimental bases of aerodynamic complexes available in Ukraine and in leading organizations of North America and Western Europe. This study demonstrates the real unification of deep fundamental theoretical knowledge and practical skills with experimental research based on existing modern research laboratories. Conclusion. Analysis and comparative indicators presented in paper allow us to state that based on today’s needs, the National Aerospace University "Kharkiv Aviation Institute" is capable of significant increase of the quality of training for specialists of all levels for the developed aviation and rocket-space industries of Ukraine.

Evaporation-Induced Transformations in Volatile Chemical Product-Derived Secondary Organic Aerosols: Browning Effects and Alterations in Oxidative Reactivity.

Volatile chemical products (VCPs) are increasingly recognized as significant sources of volatile organic compounds (VOCs) in urban atmospheres, potentially serving as key precursors for secondary organic aerosol (SOA) formation. This study investigates the formation and physicochemical transformations of VCP-derived SOA, produced through ozonolysis of VOCs evaporated from a representative room deodorant air freshener, focusing on the effects of aerosol evaporation on its molecular composition, light absorption properties, and reactive oxygen species (ROS) generation. Following aerosol evaporation, solutes become concentrated, accelerating reactions within the aerosol matrix that lead to a 42% reduction in peroxide content and noticeable browning of the SOA. This process occurs most effectively at moderate relative humidity (∼40%), reaching a maximum solute concentration before aerosol solidification. Molecular characterization reveals that evaporating VCP-derived SOA produces highly conjugated nitrogen-containing products from interactions between existing or transformed carbonyl compounds and reduced nitrogen species, likely acting as chromophores responsible for the observed brownish coloration. Additionally, the reactivity of VCP-derived SOA was elucidated through heterogeneous oxidation of sulfur dioxide (SO2), which revealed enhanced photosensitized sulfate production upon drying. Direct measurements of ROS, including singlet oxygen (1O2), superoxide (O2•-), and hydroxyl radicals (•OH), showed higher abundances in dried versus undried SOA samples under light exposure. Our findings underscore that drying significantly alters the physicochemical properties of VCP-derived SOA, impacting their roles in atmospheric chemistry and radiative balance.

INFLUENCE OF WELDING PARAMETERS ON THE PERFORMANCE CHARACTERISTICS OF THE THERMOCATODES

Methods of controlling welding parameters, physical and physico-chemical transformations that occur during welding are considered in the work. The physico-chemical mechanism of welding is considered - the deformation of the crystal lattice, the transfer of metal on the contacting surfaces, the mixing of deformation products, diffusion, phase transformations, the appearance of new chemical compounds - intermetallics, oxides, carbides. Studies of the influence of the main parameters of friction welding on the formation of the structure of the welded joints of the investigated alloys have been carried out. The microstructures of welded joints OT4 + VN-2AE and VT6 + VN-2AE are given. The obtained dependence of the relative strength of the OT 4 + VN-2AE connection on the parameters of the welding process. The given microstructures were obtained by SEM from the surface of OT 4 + VN-2AE and VT6 samples, based on which it was determined that the destruction begins with the formation of microcracks in the contact zone on the side of the VN-2AE niobium alloy. It was determined that a layer saturated with oxygen is formed in the diffusion zone due to which the β-modification of Ni2O5 with a significant specific volume is formed, which causes high internal stresses and the formation of microcracks. The reason for the decrease in the mechanical properties of the welded joint OT 4 + ВН-2АЕ was established - the formation of a phase (Ti-Nb) with an orthorhombic lattice, the degree of curvature of which determines the degree of strengthening of the layer and depends on the niobium content. These data are confirmed by X-ray structural analysis. The analysis of the concentration curves of niobium and titanium shows that titanium does not diffuse into the narrow contact zone of the niobium alloy, and niobium forms a wide diffusion zone in the contact zone of the OT 4 alloy. It was established that niobium contributes to the increase in the solubility of aluminum in λ-titanium, which leads to increase in weldability plasticity and corrosion resistance. It was determined that the low mechanical properties of the welded joints of the VN-2AE alloy with the OT-4 and VT-6 titanium alloys are due to the same nature - the oxidation of the niobium alloy at the welding temperature. It was established that the weak link of the welded joint is the surface of the niobium alloy.

Teaching old dogs new tricks: genetic engineering methanogens.

Methanogenic archaea, which are integral to global carbon and nitrogen cycling, currently face challenges in genetic manipulation due to unique physiology and limited genetic tools. This review provides a survey of current and past developments in the genetic engineering of methanogens, including selection and counterselection markers, reporter systems, shuttle vectors, mutagenesis methods, markerless genetic exchange, and gene expression control. This review discusses genetic tools and emphasizes challenges tied to tool scarcity for specific methanogenic species. Mutagenesis techniques for methanogens, including physicochemical, transposon-mediated, liposome-mediated mutagenesis, and natural transformation, are outlined, along with achievements and challenges. Markerless genetic exchange strategies, such as homologous recombination and CRISPR/Cas-mediated genome editing, are also detailed. Finally, the review concludes by examining the control of gene expression in methanogens. The information presented underscores the urgent need for refined genetic tools in archaeal research. Despite historical challenges, recent advancements, notably CRISPR-based systems, hold promise for overcoming obstacles, with implications for global health, agriculture, climate change, and environmental engineering. This comprehensive review aims to bridge existing gaps in the literature, guiding future research in the expanding field of archaeal genetic engineering.

Procedure for rapid determination of bile-tolerant gram-negative bacteria in drugs

The European Pharmacopoeia is a single reference study for the quality control of drugs. The official standards published within it provide a legal and scientific basis for quality control in the processes of drugs development, production and marketing. However, the long experience and the multitude of studies have demonstrated that medicinal forms represent unstable dispersed systems and can undergo various manifest or non-manifest changes, leading to drug incompatibilities. Along with the physico-chemical transformations, microbiological transformations can occur with the contamination of the final product with pathogenic, conditionally pathogenic or even saprophytic germs, especially medicines that do not undergo final sterilization or are not aseptically prepared. Microbial contamination of the drug can be an indicator of the production conditions; it can cause the instability of the product through the microbial decomposition of auxiliary substances, the alteration or definitive cancellation of the therapeutic effect of the active substances, the appearance of metabolites with toxic properties, especially those fractions of endotoxins on the wall cell of gram-negative bacteria with the development of allergenic, pyrogenic substances and the induction of the danger of local orgeneral infections. An important role is attributed to the group of bile-tolerant gram-negative bacteria as representatives of microorganisms that are inadmissible in one g/ml for the absence test and for the quantitative test <10 NCP/g/ml (probable number of bacteria), inadmissible in non-sterile medicinal products, herbal medicinal products for oral use and extracts used in their preparation. Due to the diversity of medicinal forms in terms of content, method of application, and therapeutic action, these preparations fulfil the indispensable conditions for the growth of microorganisms, therefore a primary concern is to avoid microbial contamination from the technological phase to the administration phase in order to prevent complications associated with bacterial infections. The given study reveals the testing of the procedure for the rapid determination of inadmissible microorganisms in non-sterile medicinal products and herbal drugs for oral use and the extracts used in their preparation, especially microorganisms of the group Enterobacteriaceae spp.

Xanthan gum-based edible coating effectively preserve postharvest quality of ‘Gola’ guava fruits by regulating physiological and biochemical processes

BackgroundGuava is a fruit prone to rapid spoilage following harvest, attributed to continuous and swift physicochemical transformations, leading to substantial postharvest losses. This study explored the efficacy of xanthan gum (XG) coatings applied at various concentrations (0.25, 0.5, and 0.75%) on guava fruits (Gola cultivar) over a 15-day storage period.ResultsThe results indicated that XG coatings, particularly at 0.75%, substantially mitigated moisture loss and decay, presenting an optimal concentration. The coated fruits exhibited a modified total soluble soluble solids, an increased total titratable acidity, and an enhanced sugar-acid ratio, collectively enhancing overall quality. Furthermore, the XG coatings demonstrated the remarkable ability to preserve bioactive compounds, such as total phenolics, flavonoids, and antioxidants, while minimizing the levels of oxidative stress markers, such as electrolyte leakage, malondialdehyde, and H2O2. The coatings also influenced cell wall components, maintaining levels of hemicellulose, cellulose, and protopectin while reducing water-soluble pectin. Quantitative analysis of ROS-scavenging enzymes, including superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase, revealed significant increases in their activities in the XG-coated fruits compared to those in the control fruits. Specifically, on day 15, the 0.75% XG coating demonstrated the highest SOD and CAT activities while minimizing the reduction in APX activity. Moreover, XG coatings mitigated the activities of fruit-softening enzymes, including pectin methylesterase, polygalacturonase, and cellulase.ConclusionsThis study concludes that XG coatings play a crucial role in preserving postharvest quality of guava fruits by regulating various physiological and biochemical processes. These findings offer valuable insights into the potential application of XG as a natural coating to extend the shelf life and maintain the quality of guava fruits during storage.

SYNTHESIS OF A CONTROL SYSTEM FOR THE TECHNOLOGICAL PROCESS OF BLENDING AND MELTING OF COPPER CONCENTRATES

This paper describes the synthesis of a control system for the technological process of blending and melting of copper concentrates. A basic mathematical model of the process is constructed taking into account the kinetics of chemical reactions, that is, all equations represent a mathematical model that describes the main physico-chemical and thermal transformations occurring in the considered zones of the process of charging and electric melting of copper concentrates. In this work, it is assumed that physico-chemical transformations of matter take place in the main bath. Then the material balance of the mat bath receiving zone (zone IV) consists of two items: the receipt of materials from zone III and the removal of materials with the resulting mat. Also, here the equations are a mathematical model describing the basic physico-chemical and thermal transformations occurring in the considered zones of the process of electric melting of copper concentrates. The constructed model can be further used in the field of automation of technological processes and productions, in metallurgy, in mechanical engineering, in industry.

Experimental measurement and molecular dynamics simulation analysis of thermal aging performance in composite solid propellants

As a complex mixed system, the aging mechanism of high-energy composite materials involves the aging of each component itself, interactions between components, and transformation of microstructural and thermodynamic properties. The study of a single component or performance parameter has great limitations for elaborating the cognitive complexity of aging processes, making it difficult to reveal the underlying principles of physicochemical property transformation. Thus, it can only be applied as an empirical summary. In view of this, this study comprehensively utilized numerical analysis and experimental detection to explore the evolution of micromolecular conformation and changes in macro aging performance from four aspects of composite systems, including binder aging, plasticizer migration, bond interface debonding, and mechanical property transformation. There was good consistency observed between molecular simulation and thermal aging experiments, indicating that there was basically no post curing process for HTPB propellants using TDI as the curing agent. In the early stage of aging, scission chain was the main process and, in the later stage of aging, oxidation crosslinking the main process. Oxidative crosslinking increased the mean square radius of gyration and glass transition temperature of the binder system, reduced the peak value of radial distribution function, and revealed the reason for the change of propellant hardness and CC and CO double bond content. However, chain degradation increased the number of polar groups, enhanced intermolecular polarity, reduced the solubility parameter, and increased the free volume fraction of the mixed system and the dioctyl sebacate diffusion coefficient. This resulted in an increase in the tangent value of the HTPB propellant loss angle from 0.43 to 0.44° and a decrease in the glass transition temperature from 203.3 to 202.0 K. The binding energy at the interfaces of AP/HTPB and Al/HTPB increased first and then decreased, which was consistent with SEM images of bonding interfaces. The joint effect of binding energy and mechanical properties of the binder system promoted the transformation of the stress-strain curve of aging propellant.

Investigation of the Physicochemical Properties and its Correlation during Koji-Moromi Fermentation Stage of Production Soy Sauce Naturally Brewed in Central Java, Indonesia

Soy sauce, a widely consumed condiment, undergoes intricate physicochemical transformations during its natural fermentation process. This research delved into the analysis of physical and chemical properties in naturally brewed soy sauce, aiming to elucidate the impact of fermentation stages (Koii, earlier moromi, final moromi, soy sauce product) and sample variations on these properties. Parameters such as pH, total acid, total soluble solids, and water activity (aw) were assessed. Additionally, chemical attributes were analyzed, including total nitrogen, crude protein, formol nitrogen, and sodium chloride (NaCl) content. The correlation between physical and chemical properties during the fermentation stages was determined using the principal component analysis (PCA) method. The fermentation process significantly affected soy sauce's physical and chemical properties. Key factors include total dissolved solids, water activity, total acids, salt, total nitrogen, crude protein, and formol nitrogen, which display distinct patterns. These fluctuations were primarily driven by microbial activity and enzymatic hydrolysis, and total nitrogen, crude protein, and formol nitrogen play pivotal roles in characterizing soy sauce quality. Remarkably, total acid content and pH values exhibited significant variations that deviate from expected correlations due to weak acids. Samples C and D were deemed the most suitable out of the five tested, aligning better with quality standards for soy sauce. This study sheds light on the complex physicochemical changes during soy sauce fermentation, emphasizing the impact of raw materials and microbial processes on its properties.

Optimizing bone and biomass co-torrefaction parameters: High-performance arsenic removal from wastewater via co-torrefied bone char

This study aimed to investigate bone char's physicochemical transformations through co-torrefaction and co-pyrolysis processes with biomass. Additionally, it aimed to analyze the carbon sequestration process during co-torrefaction of bone and biomass and optimize the process parameters of co-torrefaction. Finally, the study sought to evaluate the arsenic sorption capacity of both torrefied and co-torrefied bone char. Bone and biomass co-torrefaction was conducted at 175 °C–300 °C. An orthogonal array of Taguchi techniques and artificial neural networks (ANN) were employed to investigate the influence of various torrefaction parameters on carbon dioxide sequestration within torrefied bone char. A co-torrefied bone char, torrefied at a reaction temperature of 300 °C, a heating rate of 15 °C·min−1, and mixed with 5 g m of biomass (wood dust), was selected for the arsenic (III) sorption experiment due to its elevated carbonate content. The results revealed a higher carbonate fraction (21%) in co-torrefied bone char at 300 °C compared to co-pyrolyzed bone char (500–700 °C). Taguchi and artificial neural network (ANN) analyses indicated that the relative impact of process factors on carbonate substitution in bone char followed the order of co-torrefaction temperature (38.8%) > heating rate (31.06%) > addition of wood biomass (30.1%). Co-torrefied bone chars at 300 °C exhibited a sorption capacity of approximately 3 mg g−1, surpassing values observed for pyrolyzed bone chars at 900 °C in the literature. The findings suggest that co-torrefied bone char could serve effectively as a sorbent in filters for wastewater treatment and potentially fulfill roles such as a remediation agent, pH stabilizer, or valuable source of biofertilizer in agricultural applications.

Pre-treatment of hydrolysable nuclear organic liquids prior to their waste management: Solid impregnation of vegetable oil on surfactant-grafted clay particles

In the context of advancing nuclear waste management techniques, this study delves into the novel use of surfactant-grafted clay particles for pre-treating hydrolysable nuclear organic liquids. Our research explores the potential of modified clay materials in immobilizing vegetable oil, a surrogate for complex nuclear waste. We investigate the adsorption capabilities of various clays, including metakaolin, diatomaceous earth and sepiolite, when grafted with cetyltrimethylammonium bromide (CTAB) as cationic surfactant, or decyl glucoside (DG) as non-ionic surfactant. This study employs characterization techniques to assess the physicochemical transformations in clays post surfactant-grafting. Grafting was initially highlighted by TGA, where the breakdown of surfactants can be observed. This is also evidenced by measurements of the ζ-potential, which demonstrate a reduction in surface charge upon the addition of the cationic surfactant, excepted for sepiolite for which the surface charge did not change. Additionally, Washburn measurements indicate that the grafting process converts hydrophilic particles into hydrophobic ones. The oil absorption tests indicated that the CTAB-grafted sepiolite demonstrated superior characteristics, notably exhibiting no oil rejection. Consequently, this specifically synthesized powder was utilized in a two-step process consisting in pre-impregnation of oil up to 20 %v of vegetable oil prior to its immobilization within a geopolymer matrix. Furthermore, the outcomes of the leaching tests revealed that the vegetable oil remained effectively confined within the immobilization matrix, ensuring its retention. The research contributes to the goal of enhancing hydrolysable nuclear waste management practices, ensuring long-term sustainability and environmental safety.

KINETIC CHARACTERISTICS OF THERMOLYSIS PROCESSES OF WASTE RUBBER PRODUCTS

In this paper, the kinetic parameters of various stages of the processes occurring during the thermal decomposition of waste rubber products are determined. To study the physico-chemical and chemical transformations occurring in waste samples of rubber products with temperature changes, a thermal analysis was carried out. It has been established that the processes of thermal destruction of the carbon component of rubber products are similar to the processes occurring during pyrolysis of solid natural combustible minerals, and conditionally consist of four stages. On the basis of the derivatogram, the temperatures of the endothermic minima were determined, and the temperatures of the processes were determined from the beginning of the peaks of the effects on the DTA curve. To determine the kinetic parameters of various stages of the process of thermal destruction of rubber products without air access, the Arrhenius law was used as the initial equation, which describes the dependence of the reaction rate constant on temperature. It is established that a first-order kinetic equation is acceptable for the process of thermal decomposition of waste rubber products during pyrolysis, activation energies and pre-exponential multipliers of each stage of thermal decomposition are calculated. The lowest reaction rate is observed in the temperature range of 510-780 °C, respectively, this stage is limiting and determines the rate of the process. Based on the results of thermal analysis, a method has been proposed and developed that allows to obtain a refined solid carbon-containing pyrolysis residue by calcining it at a temperature of 800-850 °C in an oxygen-free environment until the complete cessation of gas emission processes. The data obtained are necessary for modeling the pyrolysis process of rubber products on a production scale. Based on laboratory studies and experimental data obtained, it is possible to optimize existing pyrolysis plants for rubber waste. For citation: Makarevich E.A., Papin A.V., Cherkasova T.G. Kinetic characteristics of thermolysis processes of waste rubber products. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 5. P. 107-113. DOI: 10.6060/ivkkt.20246705.6937.

Physicochemical transformation of gasification slags with different residue carbon contents during sintering/melting process

The ash residue after gasification in the coal gasifier contains a certain proportion of residual carbon, which exerts a significant effect on the slag properties such as sintering, melting, and flow within the furnace. The residues discharged outside the gasifier retain the distribution patterns of ash and residual carbon under gasification conditions. This study selected coarse and fine residues generated from an entrained-flow gasifier and investigated the transformation of slags with different carbon contents during heating process. The obtained ash residues underwent characterization to determine the modes of the compositions occurrence. Subsequently, ash residues with different carbon contents were observed for the sintering-melting processes with a high-temperature confocal scanning laser microscope (CSLM). With the aid of FactSage, the physicochemical transformation of slag particles was determined. The impact of residual carbon on particle characteristics manifests in both physical structure and chemical reactions. On one hand, residue residual carbon can act as a skeleton during the melting process, causing the molten phase to enter the pores of porous carbon, intensifying particle shrinkage. After the inorganic components melt, the liquid encapsulated by carbon retains the original particle shape. On the other hand, the carbon can react with the inorganic ash components. If the carbon content is less than 6%, a new FexSi with a high ash melting point can be formed. As the carbon content increases, the carbon reacts with the Si to form SiC. This implies a reduction in the liquid content. Therefore, the flow temperature is greatly delayed by an increase in carbon content above 14%.