Pub Date : 2023-08-08DOI: 10.15826/chimtech.2023.10.3.06
M. Popov, M. Chudakova, P. B. Kurmashov, A. Bannov, A. V. Kleimenov, Prof. N. Uvarov, Prof. E. Aubakirov
The work is devoted to the study of the novel process of catalytic decomposition of light hydrocarbons on a catalyst at temperatures of 550 °С and 600 °C at various pressures. The CVD process is a new COx-free approach for hydrogen production. A glass fiber fabric was used as a catalyst, which was preliminarily modified by the application of additional outer layers of NiO and porous silica. A technical mixture of propane and butane was used as feedstock. The main purpose is to investigate the effects of pressure and temperature on the production of hydrogen and carbon nanofibers over a glass-based catalyst. As a result of the decomposition of the mixture, the yield of hydrogen was 266–848 L/gcat, and that of carbon nanofibers was 3–10 g/gcat. Increasing the pressure of propane-butane mixture decomposition led to an increase of the catalyst lifetime. The highest yield of hydrogen and carbon nanofibers was achieved at 1 bar and 600 °C.
{"title":"Decomposition of light hydrocarbons on a Ni-containing glass fiber catalyst","authors":"M. Popov, M. Chudakova, P. B. Kurmashov, A. Bannov, A. V. Kleimenov, Prof. N. Uvarov, Prof. E. Aubakirov","doi":"10.15826/chimtech.2023.10.3.06","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.3.06","url":null,"abstract":"The work is devoted to the study of the novel process of catalytic decomposition of light hydrocarbons on a catalyst at temperatures of 550 °С and 600 °C at various pressures. The CVD process is a new COx-free approach for hydrogen production. A glass fiber fabric was used as a catalyst, which was preliminarily modified by the application of additional outer layers of NiO and porous silica. A technical mixture of propane and butane was used as feedstock. The main purpose is to investigate the effects of pressure and temperature on the production of hydrogen and carbon nanofibers over a glass-based catalyst. As a result of the decomposition of the mixture, the yield of hydrogen was 266–848 L/gcat, and that of carbon nanofibers was 3–10 g/gcat. Increasing the pressure of propane-butane mixture decomposition led to an increase of the catalyst lifetime. The highest yield of hydrogen and carbon nanofibers was achieved at 1 bar and 600 °C.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45692131","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}
Pub Date : 2023-08-07DOI: 10.15826/chimtech.2023.10.4.01
H. Tran, Dinh Quan Nguyen
Adsorption is a widely used technique for the treatment of wastewater containing dyes, which are pollutants that can have serious impacts on the aquatic ecosystems. In this work, activated carbon (AC) was prepared from cashew nut shell (CNS) and used to adsorb methylene blue (MB) from solution. The CNS AC was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and nitrogen adsorption-desorption isotherms. The adsorption behavior of MB on CNS AC was investigated by varying the initial solution pH, adsorbent dosage, and initial MB concentration. The results showed that the CNS AC was effective for MB removal, with an adsorption capacity of 24.8 mg/g. The adsorption nature of MB onto the CNS AC surface was explored by analyzing the experimental data using isotherm and kinetic models. The Freundlich and Dubinin-Radushkevich (D-R) isotherm models showed good agreement with the experimental adsorption equilibrium results. The mean adsorption energy was found to be 22.4 kJ/mol, indicating chemical adsorption. The adsorption of MB on the CNS AC followed pseudo-second-order kinetics. This study demonstrates the potential application of CNS AC for MB removal.
{"title":"Study on methylene blue adsorption using cashew nut shell-based activated carbon","authors":"H. Tran, Dinh Quan Nguyen","doi":"10.15826/chimtech.2023.10.4.01","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.4.01","url":null,"abstract":"Adsorption is a widely used technique for the treatment of wastewater containing dyes, which are pollutants that can have serious impacts on the aquatic ecosystems. In this work, activated carbon (AC) was prepared from cashew nut shell (CNS) and used to adsorb methylene blue (MB) from solution. The CNS AC was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and nitrogen adsorption-desorption isotherms. The adsorption behavior of MB on CNS AC was investigated by varying the initial solution pH, adsorbent dosage, and initial MB concentration. The results showed that the CNS AC was effective for MB removal, with an adsorption capacity of 24.8 mg/g. The adsorption nature of MB onto the CNS AC surface was explored by analyzing the experimental data using isotherm and kinetic models. The Freundlich and Dubinin-Radushkevich (D-R) isotherm models showed good agreement with the experimental adsorption equilibrium results. The mean adsorption energy was found to be 22.4 kJ/mol, indicating chemical adsorption. The adsorption of MB on the CNS AC followed pseudo-second-order kinetics. This study demonstrates the potential application of CNS AC for MB removal.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43509206","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}
Pub Date : 2023-08-04DOI: 10.15826/chimtech.2023.10.3.05
A. Kenessova, A. Rakhym, Bagashar B. Zhaksybay, G. Seilkhanova
Despite the abundance of water bodies on Earth, there is a limited amount of potable water. Therefore, the desalination process is of great interest. Adsorption of the main contaminants of saline water (Na+, K+, Cl– ions) is an alternative process of desalination. In the present work, a sorbent based on natural zeolite (NZ) modified with ammonium chloride (NH4Cl) is obtained and the effect of modification on the removal of Na+ and K+ ions from saline water is studied. According to the Brunauer-Emmett-Teller (BET) analysis, the modification of zeolite with NH4Cl leads to an increase in its surface area (7.85 to 8.09 m2/g). According to the results of the cation exchange capacity (CEC) determination, the modification leads to a decrease in total CEC of zeolite (431.67±29.01 to 300.88±31.86 meq/100 g). According to the obtained results, ammonia modification enhances the adsorption ability of NZ to extract Na+ and K+ ions from saline water. The extraction degree (E) of Na+ ions by NH4-Z increases from 7.93±1.63 to 10.44±1.52%, while for K+ ions it increases about 2 times (27.69±2.45 to 56.46±3.71%). These results indicate that the ammonia-modified NZ can potentially be used as a desalination agent for the removal of Na+ and K+ ions from saline water.
{"title":"The effect of ammonia activation on the desalination potential of natural zeolite","authors":"A. Kenessova, A. Rakhym, Bagashar B. Zhaksybay, G. Seilkhanova","doi":"10.15826/chimtech.2023.10.3.05","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.3.05","url":null,"abstract":"Despite the abundance of water bodies on Earth, there is a limited amount of potable water. Therefore, the desalination process is of great interest. Adsorption of the main contaminants of saline water (Na+, K+, Cl– ions) is an alternative process of desalination. In the present work, a sorbent based on natural zeolite (NZ) modified with ammonium chloride (NH4Cl) is obtained and the effect of modification on the removal of Na+ and K+ ions from saline water is studied. According to the Brunauer-Emmett-Teller (BET) analysis, the modification of zeolite with NH4Cl leads to an increase in its surface area (7.85 to 8.09 m2/g). According to the results of the cation exchange capacity (CEC) determination, the modification leads to a decrease in total CEC of zeolite (431.67±29.01 to 300.88±31.86 meq/100 g). According to the obtained results, ammonia modification enhances the adsorption ability of NZ to extract Na+ and K+ ions from saline water. The extraction degree (E) of Na+ ions by NH4-Z increases from 7.93±1.63 to 10.44±1.52%, while for K+ ions it increases about 2 times (27.69±2.45 to 56.46±3.71%). These results indicate that the ammonia-modified NZ can potentially be used as a desalination agent for the removal of Na+ and K+ ions from saline water.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44992556","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}
Pub Date : 2023-08-03DOI: 10.15826/chimtech.2023.10.3.04
E. Timakova, Tatiana E. Timakova, Liubov I. Afonina
The processes of oxidative thermolysis of bismuth(III) DL-tartrate BiC4H3O6 obtained by the interaction of high-purity basic bismuth(III) nitrates [Bi6O4(OH)4](NO3)6·H2O and [Bi6O5(OH)3](NO3)5·3H2O with DL-tartaric acid solution have been investigated. The products of precipitation have been studied by methods of X-ray diffraction and thermal analysis, IR and Raman spectroscopy and chemical analysis. The staging of thermal transformation processes has been determined. Morphological studies and grain size analysis of initial precursors and final products of their thermal transformations have been carried out. The possibility of obtaining fine crystalline powders of tetragonal bismuth(III) oxide modification β-Bi2O3 by oxidative thermolysis of DL-BiC4H3O6 has been shown.
{"title":"High purity β-Bi2O3 preparation by thermal decomposition of tartrates","authors":"E. Timakova, Tatiana E. Timakova, Liubov I. Afonina","doi":"10.15826/chimtech.2023.10.3.04","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.3.04","url":null,"abstract":"The processes of oxidative thermolysis of bismuth(III) DL-tartrate BiC4H3O6 obtained by the interaction of high-purity basic bismuth(III) nitrates [Bi6O4(OH)4](NO3)6·H2O and [Bi6O5(OH)3](NO3)5·3H2O with DL-tartaric acid solution have been investigated. The products of precipitation have been studied by methods of X-ray diffraction and thermal analysis, IR and Raman spectroscopy and chemical analysis. The staging of thermal transformation processes has been determined. Morphological studies and grain size analysis of initial precursors and final products of their thermal transformations have been carried out. The possibility of obtaining fine crystalline powders of tetragonal bismuth(III) oxide modification β-Bi2O3 by oxidative thermolysis of DL-BiC4H3O6 has been shown.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44744704","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}
Pub Date : 2023-07-31DOI: 10.15826/chimtech.2023.10.3.03
T. Malinovskaya, S. Ghyngazov, Alexander I. Aparnev, V. Zhek
We investigated the feasibility of synthesizing nanopowders containing indium and dysprosium oxides by the glycine-nitrate method. It was found that the glycine-nitrate method significantly reduces the content of the indium component in the resulting mixture of indium and dysprosium oxides. In this case, intensive absorption of carbon dioxide from the air by the formed particles induces formation of amorphous carbonaceous compounds, which decompose only under high-temperature treatment (900 °C). This prevents compaction of powders synthesized by the glycine-nitrate method. Comparison of the characteristics of powders containing indium oxides and dysprosium, synthesized by the glycine-nitrate method and by the method of co-precipitation of indium and dysprosium hydroxides from chloride solutions, showed the advantage of the co-precipitation method in the pressing of powders.
{"title":"Synthesis of nanopowders by the glycine-nitrate method in the In-Dy-O system","authors":"T. Malinovskaya, S. Ghyngazov, Alexander I. Aparnev, V. Zhek","doi":"10.15826/chimtech.2023.10.3.03","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.3.03","url":null,"abstract":"We investigated the feasibility of synthesizing nanopowders containing indium and dysprosium oxides by the glycine-nitrate method. It was found that the glycine-nitrate method significantly reduces the content of the indium component in the resulting mixture of indium and dysprosium oxides. In this case, intensive absorption of carbon dioxide from the air by the formed particles induces formation of amorphous carbonaceous compounds, which decompose only under high-temperature treatment (900 °C). This prevents compaction of powders synthesized by the glycine-nitrate method. Comparison of the characteristics of powders containing indium oxides and dysprosium, synthesized by the glycine-nitrate method and by the method of co-precipitation of indium and dysprosium hydroxides from chloride solutions, showed the advantage of the co-precipitation method in the pressing of powders.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46772034","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}
Pub Date : 2023-07-27DOI: 10.15826/chimtech.2023.10.3.02
Dmitry O. Zelentsov, Y. Petrova, Alexander V. Korobkin, A. Ivanova, A. Cheremisin, I. Shanenkov, A. Pak, Y. Mateyshina
Dispersion and aggregation of nanoparticles in aqueous solutions are important factors for safe and effective application of nanoparticles, for instance, in the oil industry. As conventional oil reserves are depleted, it is necessary to advance chemical enhanced oil recovery (cEOR) techniques to develop unconventional oil reservoirs. Nanoparticles modified by surfactants can be a promising reagent in cEOR. These nanomaterials can reduce interfacial tension and change the wettability of reservoir rock, which leads to an increase in oil recovery. However, the application of nanoparticles is limited by their substantial aggregation in aqueous solutions. The purpose of this work is to select nanoparticles for obtaining stable sols in water in the presence of an anionic surfactant and to optimize the conditions (pH) for further modifying the nanoparticles with the anionic surfactant. Sodium dodecyl sulfate (SDS) is used as an anionic surfactant. The aggregation of oxide and carbon nanoparticles in water and anionic surfactant solutions was studied by laser diffraction, dynamic and electrophoretic light scattering methods. Most of the studied nanoparticles in water form aggregates with bi-, three- and polymodal particle size distributions. TiO2 nanoparticles obtained by plasma dynamic synthesis form the most stable sols in anionic surfactant solutions. The range of 5–7 pH is defined as optimal for their modification with surfactants. The stability of carbon nanoparticles in aqueous solutions increases significantly in the presence of a surfactant. The obtained results form the basis for further research on the modification of marked nanoparticles in surfactant solutions.
{"title":"Influence of anionic surfactant on stability of nanoparticles in aqueous solutions","authors":"Dmitry O. Zelentsov, Y. Petrova, Alexander V. Korobkin, A. Ivanova, A. Cheremisin, I. Shanenkov, A. Pak, Y. Mateyshina","doi":"10.15826/chimtech.2023.10.3.02","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.3.02","url":null,"abstract":"Dispersion and aggregation of nanoparticles in aqueous solutions are important factors for safe and effective application of nanoparticles, for instance, in the oil industry. As conventional oil reserves are depleted, it is necessary to advance chemical enhanced oil recovery (cEOR) techniques to develop unconventional oil reservoirs. Nanoparticles modified by surfactants can be a promising reagent in cEOR. These nanomaterials can reduce interfacial tension and change the wettability of reservoir rock, which leads to an increase in oil recovery. However, the application of nanoparticles is limited by their substantial aggregation in aqueous solutions. The purpose of this work is to select nanoparticles for obtaining stable sols in water in the presence of an anionic surfactant and to optimize the conditions (pH) for further modifying the nanoparticles with the anionic surfactant. Sodium dodecyl sulfate (SDS) is used as an anionic surfactant. The aggregation of oxide and carbon nanoparticles in water and anionic surfactant solutions was studied by laser diffraction, dynamic and electrophoretic light scattering methods. Most of the studied nanoparticles in water form aggregates with bi-, three- and polymodal particle size distributions. TiO2 nanoparticles obtained by plasma dynamic synthesis form the most stable sols in anionic surfactant solutions. The range of 5–7 pH is defined as optimal for their modification with surfactants. The stability of carbon nanoparticles in aqueous solutions increases significantly in the presence of a surfactant. The obtained results form the basis for further research on the modification of marked nanoparticles in surfactant solutions.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44040858","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}
Pub Date : 2023-07-24DOI: 10.15826/chimtech.2023.10.3.01
D. Akbayeva, I. Smagulova, Azhar Timurkyzy, B. Bakirova
In this work, we obtained complexes by mixing aqueous solution of palladium(II) chloride with polyvinylpyrrolidone and polyethylene glycol. The composition of the complex compounds was determined by potentiometric and conductometric titration. IR spectroscopy and scanning electron microscopy (SEM) confirmed the coordination of polymeric ligand to palladium and allowed evaluating the morphology and features of the complex surface. The catalytic activity of the synthesized compounds in the oxidation of octene-1 by inorganic oxidizers (NaBrO3, K2S2O8) in aqueous-organic media in dimethyl sulfoxide (DMSO) under mild conditions was calculated. The reaction product was octanone-2, obtained in good yield (62–98%). Quantitative analysis of octanone-2 was made by the gas-chromatographic method. Mass spectrometry confirms the formation of octanone-2. The complexes are able to participate in five consecutive catalytic cycles without significant loss of catalytic efficiency. Oxidation of octene-1 proceeds by the oxidation-reduction mechanism and consists of two key stages.
{"title":"Complexes of polyvinylpyrrolidone and polyethylene glycol with palladium(II) ions: characterization and catalytic activity","authors":"D. Akbayeva, I. Smagulova, Azhar Timurkyzy, B. Bakirova","doi":"10.15826/chimtech.2023.10.3.01","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.3.01","url":null,"abstract":"In this work, we obtained complexes by mixing aqueous solution of palladium(II) chloride with polyvinylpyrrolidone and polyethylene glycol. The composition of the complex compounds was determined by potentiometric and conductometric titration. IR spectroscopy and scanning electron microscopy (SEM) confirmed the coordination of polymeric ligand to palladium and allowed evaluating the morphology and features of the complex surface. The catalytic activity of the synthesized compounds in the oxidation of octene-1 by inorganic oxidizers (NaBrO3, K2S2O8) in aqueous-organic media in dimethyl sulfoxide (DMSO) under mild conditions was calculated. The reaction product was octanone-2, obtained in good yield (62–98%). Quantitative analysis of octanone-2 was made by the gas-chromatographic method. Mass spectrometry confirms the formation of octanone-2. The complexes are able to participate in five consecutive catalytic cycles without significant loss of catalytic efficiency. Oxidation of octene-1 proceeds by the oxidation-reduction mechanism and consists of two key stages.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43641494","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}
Pub Date : 2023-07-04DOI: 10.15826/chimtech.2023.10.2.14
P. Noppawan, Baramee Phungpis, Kanokkan Worawut
N-heterocyclic carbenes (NHCs) catalyze benzoin condensation, which is a unique carbon-carbon bond-forming reaction. It entails a coupling reaction between two aldehydes catalyzed by NHCs that produce a-hydroxycarbonyl compounds (acyloins). NHCs have emerged as a potent class of organocatalysts, catalyzing numerous benzoin and benzoin-type reactions. This review provides an overview of the historical development of NHCs and their application in benzoin reactions. Additionally, recent advancements in NHC catalysis, including the use of chiral NHCs, are discussed. This review aims to provide a comprehensive understanding of the current state of NHC catalysis for benzoin reactions and its potential for future developments in synthetic chemistry.
{"title":"Advancements in N-heterocyclic carbenes (NHCs) catalysis for benzoin reactions: A comprehensive review from past to present","authors":"P. Noppawan, Baramee Phungpis, Kanokkan Worawut","doi":"10.15826/chimtech.2023.10.2.14","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.2.14","url":null,"abstract":"N-heterocyclic carbenes (NHCs) catalyze benzoin condensation, which is a unique carbon-carbon bond-forming reaction. It entails a coupling reaction between two aldehydes catalyzed by NHCs that produce a-hydroxycarbonyl compounds (acyloins). NHCs have emerged as a potent class of organocatalysts, catalyzing numerous benzoin and benzoin-type reactions. This review provides an overview of the historical development of NHCs and their application in benzoin reactions. Additionally, recent advancements in NHC catalysis, including the use of chiral NHCs, are discussed. This review aims to provide a comprehensive understanding of the current state of NHC catalysis for benzoin reactions and its potential for future developments in synthetic chemistry.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43321044","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}
Pub Date : 2023-06-02DOI: 10.15826/chimtech.2023.10.2.13
F. Urakaev, N. Khan, A. Niyazbayeva, Dinar N. Zharlykasimova, M. Burkitbayev
The task of this article is to update, develop and introduce into scientific practice the method of "mechanochemical recrystallization" in solid-phase systems with small additives of the liquid phase of the solvent and solid-phase precursors to stabilize the formed nanoparticles. The essence of this method is shown using the example of mechanical activation of the S–AgNO3–NH4X system, where X = Cl, Br, I, with the addition of dimethyl sulfoxide (DMSO), and the resulting mechanochemical synthesis of sulfur-containing nanocomposites S/AgX with the controlled content of sulfur nanoparticles (nanosulfur). The predetermined content of nanosulfur in nanocomposites is ensured by a continuous process of dissolution-crystallization (recrystallization) of starting sulfur in the DMSO medium in a mechanochemical reactor. The proposed technical solution made it possible to obtain S/AgX nanocomposites by a single mechanical treatment of powder precursors – AgNO3, NH4Х, NH4NO3 (diluent), commercial sulfur and DMSO in planetary ball mills with various milling tools. The method also includes washing the water-soluble components of mechanosynthesis.
{"title":"Mechanochemical recrystallization: Forgotten basics and new possibilities","authors":"F. Urakaev, N. Khan, A. Niyazbayeva, Dinar N. Zharlykasimova, M. Burkitbayev","doi":"10.15826/chimtech.2023.10.2.13","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.2.13","url":null,"abstract":"The task of this article is to update, develop and introduce into scientific practice the method of \"mechanochemical recrystallization\" in solid-phase systems with small additives of the liquid phase of the solvent and solid-phase precursors to stabilize the formed nanoparticles. The essence of this method is shown using the example of mechanical activation of the S–AgNO3–NH4X system, where X = Cl, Br, I, with the addition of dimethyl sulfoxide (DMSO), and the resulting mechanochemical synthesis of sulfur-containing nanocomposites S/AgX with the controlled content of sulfur nanoparticles (nanosulfur). The predetermined content of nanosulfur in nanocomposites is ensured by a continuous process of dissolution-crystallization (recrystallization) of starting sulfur in the DMSO medium in a mechanochemical reactor. The proposed technical solution made it possible to obtain S/AgX nanocomposites by a single mechanical treatment of powder precursors – AgNO3, NH4Х, NH4NO3 (diluent), commercial sulfur and DMSO in planetary ball mills with various milling tools. The method also includes washing the water-soluble components of mechanosynthesis.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44158999","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}
Pub Date : 2023-05-29DOI: 10.15826/chimtech.2023.10.2.12
A. O. Cheretaeva, P. Glukhov, M. R. Shafeev, Alyona G. Denisova, E. D. Borgardt, A. Polunin, A. Katsman, M. M. Krishtal
Oxide layers on Mg97Y2Zn1 magnesium alloy with strengthening LPSO-phase were formed by plasma electrolytic oxidation (PEO) in bipolar mode with frequency variation of forming current pulses (50 and 500 Hz) and addition of sodium aluminate or sodium silicate to alkali phosphate fluoride electrolyte. Microstructure, chemical and phase composition, corrosion and mechanical properties of the oxide layers formed were investigated. With increasing current frequency for both electrolytes, an increase in homogeneity of the oxide layers structure and a decrease in their porosity and fracturing at constant thickness were recorded. The oxide layers formed at 500 Hz even with some decrease in hardness have better adhesive strength and 2 orders of magnitude higher short-term corrosion resistance values. PEO of Mg-alloy with LPSO-phase in the electrolyte with addition of sodium aluminate in combination with increased pulse frequency (500 Hz) allows forming the best-quality uniform oxide layer with high hardness, adhesive strength and corrosion resistance properties. The use of electrolyte with addition of sodium silicate reduced the adhesive strength by 1.5 times and brought down the long-term corrosion resistance of oxide layers by an order of magnitude, as compared with the electrolyte with sodium aluminate. The reason for a significant improvement in the complex of protective properties of the oxide layers with an increase in the current pulse frequency is supposed to be a decrease in the power and duration of individual microarc discharges with simultaneous increase in their number per unit oxidized area.
{"title":"Improvement of protective oxide layers formed by high-frequency plasma electrolytic oxidation on Mg-RE alloy with LPSO-phase","authors":"A. O. Cheretaeva, P. Glukhov, M. R. Shafeev, Alyona G. Denisova, E. D. Borgardt, A. Polunin, A. Katsman, M. M. Krishtal","doi":"10.15826/chimtech.2023.10.2.12","DOIUrl":"https://doi.org/10.15826/chimtech.2023.10.2.12","url":null,"abstract":"Oxide layers on Mg97Y2Zn1 magnesium alloy with strengthening LPSO-phase were formed by plasma electrolytic oxidation (PEO) in bipolar mode with frequency variation of forming current pulses (50 and 500 Hz) and addition of sodium aluminate or sodium silicate to alkali phosphate fluoride electrolyte. Microstructure, chemical and phase composition, corrosion and mechanical properties of the oxide layers formed were investigated. With increasing current frequency for both electrolytes, an increase in homogeneity of the oxide layers structure and a decrease in their porosity and fracturing at constant thickness were recorded. The oxide layers formed at 500 Hz even with some decrease in hardness have better adhesive strength and 2 orders of magnitude higher short-term corrosion resistance values. PEO of Mg-alloy with LPSO-phase in the electrolyte with addition of sodium aluminate in combination with increased pulse frequency (500 Hz) allows forming the best-quality uniform oxide layer with high hardness, adhesive strength and corrosion resistance properties. The use of electrolyte with addition of sodium silicate reduced the adhesive strength by 1.5 times and brought down the long-term corrosion resistance of oxide layers by an order of magnitude, as compared with the electrolyte with sodium aluminate. The reason for a significant improvement in the complex of protective properties of the oxide layers with an increase in the current pulse frequency is supposed to be a decrease in the power and duration of individual microarc discharges with simultaneous increase in their number per unit oxidized area.","PeriodicalId":9964,"journal":{"name":"Chimica Techno Acta","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44129639","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}
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