Chimica Techno Acta最新文献

{"title":"Structural transformations and their impact on the mechanical and antifriction properties in the process of alloying graphitized hypereutectoid steel with copper","authors":"Natalia V. Stepanova, Elena A. Lozhkina","doi":"10.15826/chimtech.2023.10.3.15","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.3.15","url":null,"abstract":"The purpose of the work is to develop a cast antifriction material based on an iron-carbon alloy with a high copper content for use in large, heavy duty sliding friction units. Using the casting method in self-hardening liquid glass mixtures, two specimens of hypereutectoid graphitized steel with different copper contents (0.09 and 8.76 wt.%) were produced. To obtain graphite in the steel structure, modification with the silicocalcium (SiCa) was used. The microstructural examination was carried out using optical metallography, SEM and TEM methods. The impact of copper on the structure as well as the mechanical and antifriction properties of graphitized hypereutectoid steel was studied. It was found that adding 8.76 wt.% of copper to the steel composition leads to an increase in the Brinell hardness level of the material from 250 to 300 HB, ultimate tensile strength from 250 to 380 MPa and compressive strength from 1050 to 1200 MPa, which is associated with an increase in the microhardness of pearlite from 350 to 420 HV. To assess the impact of copper on the sliding friction coefficient of graphitized hypereutectoid steel, a curve of sliding friction coefficient vs applied load was plotted; the experiment was carried out according to the liner-on-disk scheme. The wear resistance of materials under sliding friction conditions was also assessed using this method. Copper alloying has a positive effect on the wear resistance of graphitized hypereutectoid steel by increasing the mechanical properties of the material and also by reducing the level of the sliding friction coefficient under boundary lubrication conditions.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":"30 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135665849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of sintering duration on structure and properties of Ni-Al metal-intermetallic composites produced by SPS","authors":"Tatiana Ogneva, Alexander Anisimov, Ruslan Kuzmin, Andrey Tyurin, Yulia Emurlaeva, Natalya Aleksandrova","doi":"10.15826/chimtech.2023.10.3.14","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.3.14","url":null,"abstract":"The fabrication of Ni-Al based metal-intermetallic layered (MIL) composites is one of the actively developing directions in the production of materials for aircraft and space industries. Alternating hard intermetallic layers with ductile metal layers provides a unique combination of mechanical properties. In this study, metal-intermetallic layered composites consisting of Ni and nickel aluminides were fabricated using spark plasma sintering (SPS) of Ni and Al foils 100 and 25 μm in thickness, respectively. Samples sintered at 1100 °C for 0.5, 3, and 8 min were obtained. The purpose of this study was to fabricate Ni-Al MIL composites with increased strength properties using SPS technique and to investigate the effect of sintering duration on structure and properties. The structure of the samples sintered for 0.5 min consisted of Ni layers and intermetallic layers containing the sublayers with stoichiometric and Ni-rich B2 NiAl, L10 twinned martensite NiAl. The tensile strength of such composites was 485 MPa. The intermetallic layers in the sample sintered for 3 min have more Ni-rich NiAl, martensite NiAl, and Ni3Al phases, which promoted to an increase in tensile strength to 575 MPa. The sample sintered for 8 min consisted of Ni and a solid solution of Al in Ni and showed the highest tensile strength, 610 MPa, due to solid solution hardening in the interlayers. The samples did not break when applying bending load, which is the evidence of the good reliability and durability of the composites.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136013243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The impact of dimethylformamide on the synthesis of graphene quantum dots derived from graphene oxide","authors":"Khuong T. Truong, Thach H. Pham, Khai V. Tran","doi":"10.15826/chimtech.2023.10.4.05","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.4.05","url":null,"abstract":"Graphene quantum dots (GQDs) have garnered immense interest in recent years due to their unique optical, electrical, and chemical properties, making them promising candidates for various applications in optoelectronics, bioimaging, and sensing. However, enhancing the control over the size, surface chemistry, and optical properties of GQDs remains a significant challenge. In this study, a novel recipe was proposed to successfully synthesize various GQDs via a typical solvothermal process, which has proven to be a versatile and scalable approach. In addition to the main ingredient – graphene oxide suspension, dimethylformamide (DMF) and hydrogen peroxide serving as a cutting agent were added to the reaction mixture. This synthesis method was found to be more promising than the reference one in which DMF was replaced by double distilled water. Through systematic experimentation, we demonstrated that the addition of DMF enables the successful GQD production over a wider range of reaction times; hence, the UV absorption band and photoluminescence properties of GQDs can be better adjusted. The dependence of photoluminescence on the excitation wavelength was observed in the as-prepared materials as they were excited with a range of wavelengths from 360 to 480 nm. The obtained insights not only advance our understanding of GQD synthesis but also open up avenues for tailoring their properties for specific applications.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":"2015 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136359254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthesis of highly-porous nitrogen-doped carbon materials by pyrolysis of melamine-formaldehyde resin using a hard template","authors":"Yuliya Sinelnikova, Alexander Nizovskii , Nikolai Uvarov","doi":"10.15826/chimtech.2023.10.3.13","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.3.13","url":null,"abstract":"The use of nitrogen-doped carbon materials as electrodes in supercapacitors is a promising area of research. In this study highly-porous nitrogen-containing carbon materials were obtained by pyrolysis of melamine formaldehyde resin in the presence of nanocrystalline MgO as a hard template that was washed off after the pyrolysis. Magnesium citrate was used as a precursor for the synthesis of the template agent in situ during the pyrolysis of the resin. The obtained materials were characterized by X-ray diffraction, BET nitrogen adsorption method and Raman spectroscopy. The presence of nitrogen in the amount of 4 atomic percent was proved by XPS spectroscopy. The specific surface area was found to increase monotonically from 10 to 1300 m2/g with an increase in the content of magnesium citrate in the initial mixture. The samples showed high capacitance of 120 F/g in 1 M H2SO4 electrolyte and can be used in supercapacitors.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135646774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Use of electrochemical impedance spectroscopy to assess the stability of the anion exchange membrane MA-41, modified by poly-N,N-diallylmorpholine bromide in overlimiting current modes","authors":"Denis A. Bondarev, Aslan R. Achoh, Alexander V. Bespalov, Stanislav S. Melnikov, Mikhail V. Sharafan, Viktor I. Zabolotskiy","doi":"10.15826/chimtech.2023.10.4.04","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.4.04","url":null,"abstract":"The paper presents the results of studying the electrochemical characteristics and long-term stability of MA-41 membranes on the surface of which poly-N,N-diallylmorpholinium bromide was applied. The deposition of a polyelectrolyte on the membrane surface leads to an increase in the limiting current from 0.8 to 1.1 mA/cm2. The comparison of the experimental and theoretically calculated values of the limiting current density allows us to conclude that the modification of the membrane surface by poly-N,N-diallylmorpholinium bromide does not lead to the formation of a continuous polyelectrolyte film on the surface, but its fixation occurs due to the sorption of macromolecules on the surface of the ion-exchanger particles. To quantify the rate of the water dissociation reaction at the membrane/solution interface, the method of electrochemical impedance was used, which makes it possible to compare the rate constants of the water dissociation reaction for different membranes, assuming that the reaction is described by the Gericher impedance. It is shown that modification of the MA-41 membrane surface leads to a decrease in the rate of the water dissociation reaction in the current range i = 1.5–4ilim by a factor of 2–6. The reduction in water dissociation reaction rate is attributed to the substitution of catalytically active secondary and tertiary amino groups in the surface layer of the pristine membrane by stable heterocyclic ammonium bases of poly-N,N-diallylmorpholinium. The study of the long-term stability of the resulting membrane showed that when the membrane is polarized with a current equal to twice the limiting current, the desorption of the modifier occurs within 25 h, and the properties of the membrane become close to those of the unmodified MA-41 membrane. It was shown that the electrochemical impedance method can be used as a very sensitive method for studying the long-term stability of ion-exchange membranes.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135786179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The most effective techniques of industrial purification processes: a technical review","authors":"Iltifat Hameed Saud, Forat Yasir AlJaberi","doi":"10.15826/chimtech.2023.10.4.03","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.4.03","url":null,"abstract":"This paper reviews various separation techniques used in purification processes to remove pollutants like carbon dioxide and hydrogen sulfide from petroleum products. The most effective techniques include absorption, adsorption, cryogenic distillation, chemical looping combustion, and membrane separation. The study reviews over 100 published studies to assess their characteristics, benefits, and drawbacks. The choice of separation technology depends on ideal conditions, cost, efficiency, and energy required in the regeneration phase.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135364012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Copolymer of chitosan with acrylamide: electron beam stimulated synthesis, structure and properties","authors":"Ilia M. Antonov, Mikhail A. Mikhailenko, Tatyana P. Shakhtshneider, Ilia V. Eltsov, Svetlana A. Kuznetsova, Maxim V. Zelikman, Alexander A. Bryazgin","doi":"10.15826/chimtech.2023.10.3.12","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.3.12","url":null,"abstract":"The aim of this research was to obtain the grafted copolymer of chitosan with acrylamide using the electron beam irradiation. Radiation dose was varied from 6 to 160 kGy. The highest yield of the product was observed at radiation dose of 12–40 kGy. Further increase in the dose caused a decrease in the product yield as well as its solubility in water. Using gel permeation chromatography, it was confirmed that unreacted chitosan remained in the product. NMR study of the water-soluble part of the product obtained under the doses of 6, 12, and 20 kGy showed that the length of the side chains of grafted acrylamide was about 2 elementary units. Investigation of chitosan solutions by means of dynamic light scattering revealed the presence of chitosan agglomerates in the solution. The possibility of obtaining dense films was demonstrated. Mechanical treatment of the copolymer in the ball mill caused an increase in the solubility of the samples obtained even at radiation doses of 80 and 160 kGy. It was determined by means of chromatographic methods that there were no products with low molecular weight in the ball-milled product, and unreacted chitosan did not undergo mechanocracking during the mechanical treatment.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135990897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthesis and properties of polymer electrolytes based on polyurethane elastomer and lithium salts","authors":"N.Ya. Fedorov, A. Ulihin, Nikolai Uvarov","doi":"10.15826/chimtech.2023.10.3.11","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.3.11","url":null,"abstract":"Polymer solid electrolytes were obtained by swelling the polyurethane elastomer with solutions of lithium salts LiBF4 and LiClO4 in DMSO at different concentration of lithium salt. The swelling effect was found to decrease with the increase in the salt concentration, whereas, the ionic conductivity has a maximum of 6–8·10–4 S/cm at 5 wt.% lithium salt. The salt solutions incorporated into the polymer pores have melting points ranging from –10 to 2 °C and de-swelling takes place at low temperatures. The obtained polyurethane elastomer materials have a high conductivity and may be promising for use in flexible lithium polymer batteries.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47937900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrophilic molecularly imprinted phenol-amine-formaldehyde resins","authors":"Y. Petrova, E. V. Bulatova, Dmitry O. Zelentsov, Y. Mateyshina","doi":"10.15826/chimtech.2023.10.3.10","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.3.10","url":null,"abstract":"Hydrophilic molecularly imprinted resins (MIR), which are produced using hydrophilic monomers such as phenols, aldehydes, melamine or urea, have recently attracted increasing attention for use in separation and preconcentration. Among their obvious advantages are good sorption capacity, high recovery and selectivity, as well as their reusability in aqueous solutions. In this work we applied the bulk molecular imprinting method to produce quercetin-imprinted phenol-amino-formaldehyde resin. For this purpose, phloroglucinol and melamine solutions were mixed with formaldehyde and then polyethylene glycol and quercetin (Qu) were added to the obtained solution as a porogen and a template, respectively. The mixture was stirred under heating, then left in the thermostat for a continuous time. The optimum ratio of phloroglucinol to melamine was 3:1. The average molecular mass of porogen (Mw) varied between 4000–10000 Da. The obtained MIR were eluted with ethanol-water mixture (4:1, v/v) in the Soxhlet extractor for 36 h to remove the template. The MIR were characterized by FTIR-spectroscopy, laser diffraction spectroscopy and differential thermal analysis. The maximum recovery and sorption capacity of MIR synthesized in the presence of a porogen with Mw 10000 were 47% and 4.7 μmol Qu/g, respectively. The maximum imprinting factor was 1.41. The sorption kinetics of quercetin by a non-imprinted resin (NIR) is best described by a pseudo-second-order model, while MIR has a mixed pseudo-first-second-order mechanism.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44910112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of nanostructured catalysts for catalytic oxidative water purification from organic impurities, including phenolic compounds","authors":"Larissa R. Sassykova, B. Dossumova, M. S. Ilmuratova, T. Shakiyeva, B. Baizhomartov, A. Sassykova, Zh. M. Zhaxibayeva, T. Abildin","doi":"10.15826/chimtech.2023.10.3.09","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.3.09","url":null,"abstract":"The purpose of this work was to create magnetic nanocatalysts that could be used for the oxidation of organic water pollutants – phenol and its derivatives – and to determine the physicochemical characteristics of the catalysts. The development of such active nanocomposite catalysts would solve the environmental problem in the Republic of Kazakhstan in the field of wastewater treatment from organic impurities, including phenols, and would also contribute to the subsequent creation of domestic production of oxygen-containing compounds, since almost the entire spectrum of oxygen-containing compounds for various industries is imported into the Republic. Nanosized magnetic composites based on Fe and Co were obtained by chemical deposition, in some cases, using polyethyleneimine and polyvinylpyrrolidone. It was shown that the interaction between nanoparticles and the polymer takes place in the case of a CoFe2O4 catalyst stabilized with polyvinylpyrrolidone or polyethyleneimine, which may indicate the efficient formation of nanocomposites. According to the IR study, for the CoFe2O4 nanocomposite stabilized with polyvinylpyrrolidone, the absorption bands at 735, 663, 649, 626 cm–1 are natural vibrations for the composite nanoparticles embedded in a polyvinylpyrrolidone matrix. The synthesized nanocomposites were tested in the oxidation of phenol with oxygen. The results demonstrate that the catalysts are promising both for the purification of industrial wastewater from phenol and for the synthesis of oxygen-containing compounds in the liquid phase under mild conditions.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42890285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}