Archives

Extraction of sodium hydroxide from cotton processing facilities

https://doi.org/10.58224/2619-0575-2024-7-3-102-108
Abstract
The process of extracting technological contaminants from textile materials is considered as a mass transfer process, for the intensification of which pulsed exposure to an ultrasonic field is chosen.
A lightweight fabric was selected for the study in order to eliminate the influence of surface density and fabric thickness on the kinetics of the process. The results of an experimental study of the kinetics of the extraction of so-dium hydroxide during washing after mercerization of a light standard cotton fabric are presented. The studies were carried out in laboratory conditions on a model installation with a different washing bath module without intensification and with the use of ultrasonic exposure as an intensifier. At the same time, the optimal distance from the ultrasound source to the washed tissue was determined based on previous studies. Exposure to ultrasound sig-nificantly reduces the duration of the process, especially at the initial stage. Equations for approximating the kinet-ics curves of sodium hydroxide extraction from cotton fabric without intensification and with intensification by ul-trasonic action are obtained, and their parameters are determined. The correlation of calculated and experimental data is acceptable for approximate kinetic calculations. The obtained equations can be practically used in engi-neering practice for a preliminary assessment of the duration of the process of extrusion-washing of cotton fabrics belonging to the group of light cotton fabrics from alkali in various modules of the washing bath.
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Improving the energy efficiency of the drying process of fibre materials

https://doi.org/10.58224/2619-0575-2024-7-3-109-119
Abstract
In the modern textile industry, one of the most energy-consuming and widespread processes is drying, to which fibers, yarns and fabrics are subjected after various operations (impregnation, extraction, dyeing, etc.). A complex heat and mass transfer drying process is carried out at sufficiently high temperatures and is energy-consuming. To reduce the overall energy consumption in textile production, it is necessary to carry out preliminary dehydration of materials before drying, for example, in centrifuges, intensification of drying by physical fields, etc. Modern industrial drying plants for textile materials provide sufficiently fast and uniform drying, increasing the overall efficiency of this stage of production of finished textile products. Energy-efficient solutions for the drying process can reduce the negative impact of the process on the environment. Industrial drying of textile materials is carried out in convective or contact dryers using thermal energy. In convective dryers, the drying agent is air. In contact dryers, water vapor is used to heat the drums. The article discusses important areas of improvement of the technological process and equipment designed for drying fibrous materials. These include: the introduction of me-chanical pre-drying dewatering; the choice of hybrid systems in drum dryers; utilization of condensate and steam in drum dryers; insulation of end panels and the abolition of intermediate drying in drum cylindrical dryers; con-trol of moisture content of the material to prevent drying of the fabric; reduction of dryer downtime by planning the supply of batches of fabric; the use of multiple drying of fabric in drum dryers. The improvement of the drying pro-cess of textile materials is possible with the use of an ultrasonic field, infrared radiation and other intensification methods while ensuring timely maintenance of drying equipment, programmable temperature changes during the drying process.
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Improving the impact resistance of a polymer composite material based on epoxy prepreg through the addition of nonwoven material based on polyamide 12

https://doi.org/10.58224/2619-0575-2024-7-3-120-136
Abstract
The effect of introducing nonwoven material based on polyamide PA 12-E on the mechanical properties of polymer composite materials based on the epoxy autoclave prepreg T107 was investigated. The presence of the nonwoven material slightly lowers the glass transition temperature to 171 ℃, which does not affect the feasibility of using the material up to the maximum operating temperature of 120 ℃. Electron microscopy studies of the composite's cross-sections revealed uniform distribution of the thermoplastic phase between the layers of carbon fabric as well as high adhesion of polyamide to the epoxy matrix. It was demonstrated that introducing nonwoven material does not lead to a reduction in the mechanical properties of the composites. The main advantage of composites based on nonwoven material is their enhanced resistance to impact loads. Under a free impact with energy of 6.67 J per 1 mm of the specimen, a through penetration with fiber destruction was observed in the sample without the nonwoven material, while for the sample with nonwoven material, the damage was characterized by delamination without fiber damage. The compressive strength after impact increased from 257 to 326 MPa with the introduction of nonwoven material. As a result, the proposed modification of commercial prepreg could expand the range of applications for the material and improve safety, particularly in aircraft structures.
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Optimization of the flow part of the microfluidic channel

https://doi.org/10.58224/2619-0575-2024-7-2-4-12
Abstract
In this paper, the features of microfluidic channel optimization are considered. The microfluidic channel is a key component of the microreactor, its shape and features of the hydrodynamic regime directly affect the successful course of chemical reactions carried out in it. The microfluidic industry regulates processes occurring in small volumes of liquids – on the order of a nano liter or less. It is applicable to various fields such as microelectronics, pharmaceuticals, specialty chemicals, etc. The Comsol Multiphysics computational modeling program was used as an optimization tool. It is based on the finite element method, which allows you to accurately model the problems of the hydrodynamic profile. In this article, the simplest form of a microchannel is considered – a 0.75 mm circular channel with a mixing cell. The mathematical modeling of the process is given, the optimality criterion adequate for the task is determined. As one of the components of this criterion, diodicity was used – a criterion that determines the ability to pass a stream in the forward direction, provided there is a reverse flow. As a result of this work, the most optimal shape of the microreactor channel satisfying the required process conditions was identified, the main hydrodynamic parameters were obtained and the dependence of the diode on the criterion used was determined.
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The influence of hydrogen injection together with methane on changes in the physicochemical properties of sandstone

https://doi.org/10.58224/2619-0575-2024-7-3-137-145
Abstract
The scientific basis of hydrogen storage in the environment, the causes and mechanisms of its interaction with other natural gases and fluid-containing media are poorly developed. Therefore, it is important to conduct a set of studies aimed at clarifying the main factors of its storage in UGS facilities together with methane. Changes in the physico-chemical properties of a sandstone sample after prolonged exposure to a hydrogen-methane mixture have been studied using infrared spectroscopy (IR), nuclear magnetic resonance (NMR), X-ray fluorescence analysis, and velocity measurement of longitudinal and transverse sound waves. Changes in the composition of the rock are confirmed by differences in the IR, NMR, and transformation spectra of the mineral component of sandstone, which is largely due to the crystallization processes of substances dissolved in adsorbed water. The results of these studies can be used in the planning and operation of underground gas storage facilities in regions where large-scale hydrogen production and storage will be organized.
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Electrophilic-nucleophilic and hydrophobic properties of surface-modified metals

https://doi.org/10.58224/2619-0575-2024-7-2-13-25
Abstract
The method of layering different-sized molecules of ammonium and organosilicon compounds on metals, developed at the St. Petersburg Mining University, is a promising method for hydrophobization and stabilization of the surface properties of dispersed metal materials. A comparison was made of the hydrophobicity of samples based on PMS-1 copper powder processed in pairs of modifiers in mixed or sequential modes. To provide a physicochemical substantiation of the mechanism of surface hydrophobization, quantum chemical modeling and assessment of the electrophilic-nucleophilic properties of isolated modifier molecules in the HyperChem software package, as well as their adsorption interaction with a cluster model surface in the Gaussian 09 software package, were carried out. It was established that the adsorption energy values lie in range 64–127 kJ/mol, which corresponds to the chemical interaction of ethylhydride siloxane molecules and quaternary ammonium compounds (QAC) with the metal. It has been established that samples containing modifiers with different electrophilic-nucleophilic properties in the surface layer of the metal are characterized by better hydrophobicity. Also, the key role of QAC in the hydrophobization of the surface has been established by providing a stronger heteroatomic interaction with the metal surface and the formation of a preparatory QAC sublayer for structurally similar functional groups.
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Study of sorption properties of silicon dioxide based on overburden rocks for the extraction of dyes from wastewaters

https://doi.org/10.58224/2619-0575-2024-7-2-26-42
Abstract
The article presents the results of a study of the sorption properties of silicon dioxide obtained from overburden rocks for use in the removal of methylene blue, an organic cationic thizian dye, from aqueous solutions. The aim of the study was to evaluate the sorption properties of silica and its efficiency in the removal of methylene blue from aqueous solutions. Experimental data showed that the sorption efficiency depends on temperature, pH and stirring speed. It was found that increasing pH and stirring speed promotes sorption enhancement, while increasing temperature decreases sorption efficiency. In addition, the possibility of regeneration of silica after sorption was investigated and it was shown that its sorption properties are practically unchanged after several cycles of use. The maximum sorption capacity was 515.9 μmol/g. In a previously published paper, under standard conditions, the maximum sorption capacity was 438.22 μmol/g. The results emphasize the potential of silica as an effective and sustainable sorbent for the removal of organic dyes from wastewater. Thus, silica can be recommended for multiple use in wastewater treatment processes due to its high thermal stability and durability.
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Optimization of a typical condensation process using the example of isophorone synthesis in a microchannel

https://doi.org/10.58224/2619-0575-2024-7-2-43-52
Abstract
The work is devoted to the method of obtaining isophorone in a microchannel. Numerical and experimental optimization of the process of obtaining isophorone in a microchannel has been carried out. Isophorone is an unsaturated cyclic ketone, widely used in industry as a solvent for nitrocellulose paints, as well as as an inter-mediate for the synthesis of other compounds. The synthesis was carried out in microchannels. Microchannels are channels with a diameter of less than 1 mm. Their main feature is the possibility of carrying out various types of reactions requiring high pressures and temperatures. Due to the small internal volume, all processes occurring in them are easily intensified, high accuracy and efficiency of the experiment can be achieved. Parameters such as reaction temperature and reagent consumption varied. A new approach to conducting the experiment was used, based on minimizing the control parameters used and combining them correctly. This approach requires high ac-curacy and reproducibility of the results, so the microchannels used in this work are the best choice for such tasks. A mathematical model of the reaction based on systems of equations of varying complexity has been developed. Three-dimensional and two-dimensional contour diagrams are constructed to visualize the mathematical model of the process. The best technological parameters of the process have been established.
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Composites materials based on natural chrysotile fibers

https://doi.org/10.58224/2619-0575-2024-7-1-4-21
Abstract
The article discusses the technology of production, the problems of the development of chrysotile and chrysotile cement industries in the CIS countries. The article provides information on the composition and properties of natural chrysotile fibers, data on the quality of raw materials of cement and chrysotile fibers supplied to chrysotile cement enterprises, characteristics of suspension with them, semi-finished product and properties of solidified chrysotile cement products.
The purpose of the research is to study the influence of external and internal factors, risks on the development of the chrysotile-asbestos industry, on the sales market. Identification of the dependence of the influence of the pa-rameters of chrysotile fiber and cement on the quality of finished chrysotile cement products.
Analysis of scientific literature, analysis of current production, identification and monitoring of the quality of raw materials and finished products, comparative analysis of production and consumption markets.
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Quantum model of anharmonic vibrations of a diatomic molecule with a variable force constant and a small value of the anharmonicity coefficient

https://doi.org/10.58224/2619-0575-2024-7-1-22-31
Abstract
In this work, vibrations of a diatomic molecule are considered within the framework of quantum mechanics as an anharmonic oscillator with small values of the anharmonicity coefficient. Based on well-known models of quantum harmonic and anharmonic oscillators, a new model with a variable value of the molecule force constant was created here. The force constant depends on the vibrational quantum number n and the anharmonicity coefficient . Mathematical analysis of this model confirmed its physical validity. As an example, the vibrational energy of an oxygen molecule was calculated within the framework of the model presented in the work.
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