Abstraсt: Due to wide availability, relatively low cost, renewability, and biocompatibility, cellulose-based materials are of great interest for research as oil sorbents. In this work, cellulose sorbents were obtained by processing waste paper using an aqueous alkaline solution as a cellulose solvent. The material was functionalized with methyltrimethoxysilane (MTMS) to give it hydrophobic properties. The study shows the influence of the concentration of cellulose fiber and the drying method (sublimation and supercritical) on the structural and sorption properties of the material. It has been established that an increase in the concentration of cellulose fiber reduces the porosity of sorbents and their sorption capacity. The highest value of porosity (98.4%) and sorption capacity (32.2 g/g in the sorption of machine oil) had a sample with a cellulose fiber concentration of 0.75 wt.%, obtained using supercritical drying. The research results prove that this material can be used as sorbents for oil spill response.
Keywords: oil sorbents, cellulose, waste paper recycling, oil spills, sorption, functionalization.
Abstraсt: The article presents a classification of the main and auxiliary chemical-technological equipment and a description of the automated information system developed on its basis, including a database of the results of modeling the consequences of emergencies at typical production facilities obtained using the TOXI+RISK and FLACS software packages. The automated system allows for a comprehensive analysis of emergency situations that may occur on various technological equipment. The presented software product is intended for industrial safety management at hazardous production facilities, within which emergency situations are identified and predicted, as well as planning and implementation of measures to reduce the consequences of emergency situations.
Keywords: industrial safety, accident situation, low-tonnage chemistry, non-standard equipment, software package, database.
Abstraсt: The technology being developed for accelerated stabilization of the fiber in the production of high-strength carbon fibers with a standard modulus of elasticity is economically more profitable with an increase in the speed of movement of fibers along the industrial line. However, this technological solution may negatively affect the carbonation stage of the fibers due to the reduction of the heat treatment time of the fiber. To check the influence of this factor on the properties of carbon fiber, the authors developed stabilized bundles using accelerated technology, and carbonized them at different line speeds. The test results of the obtained fibers showed a decrease in the strength and modulus of elasticity of carbon fibers with an increase in the speed of the line, but the properties obtained are within the established requirements for carbon fibers in all the parameters put forward. The use of the acquired knowledge and skills can be used in the design of industrial carbon fiber production lines using accelerated thermal stabilization technology.
Keywords: composites, polyacrylonitrile, carbon fibers, stabilization.
Abstraсt: The article considers the formation and application of a logistics approach in project activities as one of the key tools for organizing effective management of a high-tech project and the production of high-tech products, as well as ensuring the rhythm and continuity of flow processes throughout the production cycle and evaluating their effectiveness through the construction of an implemented logistics system. As an example, a network model of processes for the development of technology for the production of ceramic membranes for the isolation and purification of microbial bacteriocins for the food industry and animal husbandry is given. The scheme of operation on a filtration plant with biological fluids is shown and the method of membrane regeneration with verification of its effectiveness for isolation and purification of microbial bacteriocins is described. Thus, the article proposes a network model for organizing the processes of high-tech production of microbial bacteriocins for the food industry and animal husbandry, using membrane methods for the effective implementation of a high-tech project and its subsequent implementation
Keywords: logistics approach, knowledge-intensive production, knowledge-intensive project, microbial bacteriocins, membrane methods, organization of production processes, life cycle of knowledge-intensive products, system approach, resource modeling, network planning method, network project plan, network model.
Abstraсt: Brown coals constitute most of the part of Lena coal basin. Among the brown coal deposits of the Lena coal basin, the Kangalassky deposit has a great potential for wider development. This article presents the results of technical, petrographic and elemental analysis of brown coals from the “Upper” and “Lower seams of the Kangalassky deposit. In order to study their ore content and the presence of potentially hazardous substances, an analysis of the mineral composition of coals carried out. In addition, a thermogravimetric analysis of coals in oxidizing and inert atmospheres was carried out to the study of thermochemical processes occurring during coal combustion and high-temperature processing. Based on the obtained results, the main stages of the thermochemical destruction of coals were identified. For each identified stage, its kinetic parameters are calculated, such as activation energy, pre-exponential factor and reaction rate constant. The research results showed that the coals of both seams of the Kangalassky deposit are characterized by a high total moisture content, low ash content and low sulfur content, as well as a fairly high calorific value for a dry, ash-free state. The maceral composition of the coals is dominated by vitrinite, and macerals of the inertinite and liptinite groups are present as minor components. The analysis of the mineral part of the coals showed a low content of hazardous toxic elements. The content of elements such as arsenic, cadmium and lead are below the detection limit. A high content of strontium was also noted. Thermal analysis of coals revealed that the brown coals of the two layers of the Kangalassky deposit have a similar pattern of thermochemical destruction. The coals of the “Lower” layer compared to the coals of the “Upper” layer are characterized by higher thermal stability, as evidenced by the kinetic parameters of coal destruction in an inert atmosphere.
Keywords: brown coal, petrography, macro-microelements, thermogravimetric analysis, activation energy.
Abstraсt: In order to develop the technology of hydrothermal nanosilicon, experiments on membrane concentration of hydrothermal nanosilicon were performed, stable aqueous sols with a final SiO2 content of 220 g/dm3 were obtained. Statistical processing of experimental values of permeability and selectivity of the ultrafiltration membrane at different degrees of concentration of SiO2 nanoparticles was performed. The contents of Na+ , Ka+ , Ca2+ , Mg2+ cations, Cl- , S042- anions and the total salinity (in terms of electrical conductivity) in the initial hydrothermal solution, concentrated ash and filtrate were determined. The diameters and zeta potentials of the surface of SiO2 nanoparticles were measured. The stability of the SiO2 sol has been established for 15 months. Industrial applications of SiO2 hydrothermal sol are substantiated. The results obtained are necessary for the design of membrane installations for the concentration of hydrothermal nanosilicon and the co-extraction of Li, Rb, Cs.
Keywords: hydrothermal solution, sol of SiO2 nanoparticles, ultrafiltration, membrane permeability and selectivity, diameter and zeta potential of SiO2 nanoparticles.
Abstraсt: The catalytic activity of metal oxides and their mixtures in the reaction of cyclocarboxylation of propylene glycol with carbamide has been studied. The following metal oxides were used as catalysts: MnO, PbO, SnO2, BeO, CaO, BaO, MgO, Fe2O3, ZnO, ZrO2, CuO, TіO2, MoO3, AI2O3, MnO2, Cr2O3. It has been shown that the reaction of the formation of propylene carbonate can occur in the absence of a catalyst, however, the use of catalytically active metal oxides allows to increase the yield of propylene carbonate and reduce the yield of 2-hydroxypropyl carbamate. It is shown that metal oxides exhibiting amphoteric properties have the greatest activity in the reaction under consideration. It has been established that metal oxides exhibiting acidic properties are characterized by low catalytic activity. Mixed “balanced” catalysts consisting of a mixture of several oxides were also considered. The use of such catalysts makes it possible to increase the yield of the target product. The mechanism of interaction of a carbamide molecule with propylene glycol through the intermediate formation of 2-hydroxidepropyl carbamate is proposed. IR spectroscopic studies have shown the presence of a band 2230 cm-1, the relative intensity of which is proportional to the catalytic activity of metal oxide in the reaction of the formation of propylene carbonate.
Keywords: cyclocarbonates, propylene carbonate, propylene glycol, carbamide, metal oxides.
