O. Filonenko, A. Grebenyuk, M. Terebinska, V. V. Lobanov
Molecular models for tin dioxide nanoparticles containing 1-7 metal atoms and coordinated or constitutive water have been constructed. Dependent on the composition of the models, the coordination number of the tin atom varied from 4 to 6, and that of oxygen was 2 or 3. The considered models contained both terminal (Sn–OH) and bridging (Sn–OH–Sn) hydroxyl groups, and also bridging (Sn–O–Sn) groups. Their equilibrium spatial and electronic structures were calculated using the second-order Møller-Plesset perturbation theory method with the SBKJC valence-only basis set. To assess the gas-phase acidity of the dioxide surface, the deprotonation energy of the studied models was determined. The adsorption energy of water molecules and hydroxide ions on aprotic (incompletely coordinated) tin atoms, which act as Lewis acid centers, was calculated. In order to estimate the pKa value of the surface of tin dioxide, the Gibbs free energy was calculated for the process of formation of ion pairs due to the proton transfer from hydroxyl groups to adsorbed water molecules. Based on the analysis of the energy effects of the coordination of water molecules and of hydroxide ion, the removal of a proton and its transfer on the hydrated surface of tin dioxide, quantitative estimates have been made of the acid-base characteristics of the active sites of the SnO2 surface. The dependence of the acidity of hydroxyl groups and coordinated water molecules on the coordination number of the oxygen atom and the neighboring tin atom, as well as on the dimensions of the cluster model, was revealed. It is shown that the acidity of protonic and aprotic sites naturally decreases with an increase in the coordination number of the tin atom. The method of calculating the value of pKa used in the work for the smallest model of the SnO2×2H2O composition allows one to reproduce the experimental data for stannic acids.
{"title":"Quantum chemical simulation of acid-base properties of the surface of SnO2 nanoparticles","authors":"O. Filonenko, A. Grebenyuk, M. Terebinska, V. V. Lobanov","doi":"10.15407/hftp14.04.495","DOIUrl":"https://doi.org/10.15407/hftp14.04.495","url":null,"abstract":"Molecular models for tin dioxide nanoparticles containing 1-7 metal atoms and coordinated or constitutive water have been constructed. Dependent on the composition of the models, the coordination number of the tin atom varied from 4 to 6, and that of oxygen was 2 or 3. The considered models contained both terminal (Sn–OH) and bridging (Sn–OH–Sn) hydroxyl groups, and also bridging (Sn–O–Sn) groups. Their equilibrium spatial and electronic structures were calculated using the second-order Møller-Plesset perturbation theory method with the SBKJC valence-only basis set. To assess the gas-phase acidity of the dioxide surface, the deprotonation energy of the studied models was determined. The adsorption energy of water molecules and hydroxide ions on aprotic (incompletely coordinated) tin atoms, which act as Lewis acid centers, was calculated. In order to estimate the pKa value of the surface of tin dioxide, the Gibbs free energy was calculated for the process of formation of ion pairs due to the proton transfer from hydroxyl groups to adsorbed water molecules. Based on the analysis of the energy effects of the coordination of water molecules and of hydroxide ion, the removal of a proton and its transfer on the hydrated surface of tin dioxide, quantitative estimates have been made of the acid-base characteristics of the active sites of the SnO2 surface. The dependence of the acidity of hydroxyl groups and coordinated water molecules on the coordination number of the oxygen atom and the neighboring tin atom, as well as on the dimensions of the cluster model, was revealed. It is shown that the acidity of protonic and aprotic sites naturally decreases with an increase in the coordination number of the tin atom. The method of calculating the value of pKa used in the work for the smallest model of the SnO2×2H2O composition allows one to reproduce the experimental data for stannic acids.","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":" 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139139538","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}
Y. V. Hrebelna, E. Demianenko, M. Terets, A. Grebenyuk, Y. Sementsov, N. V. Sigareva, S. M. Makhno, M. Kartel
The interaction of graphene with fragments of polychlorotrifluoroethylene (PCTFE) has been studied by quantum chemistry methods. Within the frameworks of the density functional theory with B3LYP exchange-correlation functional, 6-31G(d,p) basis set and the Grimme dispersion correction, and the second order Møller-Plesset perturbation theory (MP2), the values of the interaction energy of graphene with polychlorotrifluoroethylene oligomers were calculated and the most probable structures of their intermolecular complexes were optimized. As a graphene model, graphene-like planes (GLP) of different sizes were chosen, namely: С40Н16, С54Н18 and С96Н24. Oligomers of polychlorotrifluoroethylene and graphene-like planes in the formed nanocomposites are located closer to each other than individual polymer links. When comparing the results of calculations by the B3LYP-D3/6-31G(d,p) and MP2/6-31G(d,p) methods, both in the case of interactions of polychlorotrifluoroethylene oligomers with each other and intermolecular complexes of polychlorotrifluoroethylene oligomers and graphene-like planes, it has been found that the second order Møller-Plesset method is characterized by a larger intermolecular distance and a lower energy of intermolecular interactions compared to the method of the density functional theory with the Grimme dispersion correction, which is explained by the fact that the MP2 method does not fully take into account the relatively small components of dispersion interactions. Analysis of the calculation results using quantum chemistry methods shows that the addition of graphene-like planes to the polychlorotrifluoroethylene polymer leads to an increase in the intermolecular interaction energy, regardless of the calculation method used and the sizes of polychlorotrifluoroethylene oligomers and graphene-like planes. This may indicate greater strength and thermal stability of the nanocomposite based on graphene-like planes with polychlorotrifluoroethylene oligomers. The zero value of the Gibbs free energy ΔGreact for the interaction of two dimers with each other is characteristic at 270 K, and the similar value of the interaction of the PCTFE dimer with GLP is at a much higher temperature (420 K). This fact reflects the growth in thermostability of nanocomposites as compared to the polymer itself.
{"title":"Theoretical study on the interaction of polychlorotrifluoroethylene fragments with graphene-like planes","authors":"Y. V. Hrebelna, E. Demianenko, M. Terets, A. Grebenyuk, Y. Sementsov, N. V. Sigareva, S. M. Makhno, M. Kartel","doi":"10.15407/hftp14.04.534","DOIUrl":"https://doi.org/10.15407/hftp14.04.534","url":null,"abstract":"The interaction of graphene with fragments of polychlorotrifluoroethylene (PCTFE) has been studied by quantum chemistry methods. Within the frameworks of the density functional theory with B3LYP exchange-correlation functional, 6-31G(d,p) basis set and the Grimme dispersion correction, and the second order Møller-Plesset perturbation theory (MP2), the values of the interaction energy of graphene with polychlorotrifluoroethylene oligomers were calculated and the most probable structures of their intermolecular complexes were optimized. As a graphene model, graphene-like planes (GLP) of different sizes were chosen, namely: С40Н16, С54Н18 and С96Н24. Oligomers of polychlorotrifluoroethylene and graphene-like planes in the formed nanocomposites are located closer to each other than individual polymer links. When comparing the results of calculations by the B3LYP-D3/6-31G(d,p) and MP2/6-31G(d,p) methods, both in the case of interactions of polychlorotrifluoroethylene oligomers with each other and intermolecular complexes of polychlorotrifluoroethylene oligomers and graphene-like planes, it has been found that the second order Møller-Plesset method is characterized by a larger intermolecular distance and a lower energy of intermolecular interactions compared to the method of the density functional theory with the Grimme dispersion correction, which is explained by the fact that the MP2 method does not fully take into account the relatively small components of dispersion interactions. Analysis of the calculation results using quantum chemistry methods shows that the addition of graphene-like planes to the polychlorotrifluoroethylene polymer leads to an increase in the intermolecular interaction energy, regardless of the calculation method used and the sizes of polychlorotrifluoroethylene oligomers and graphene-like planes. This may indicate greater strength and thermal stability of the nanocomposite based on graphene-like planes with polychlorotrifluoroethylene oligomers. The zero value of the Gibbs free energy ΔGreact for the interaction of two dimers with each other is characteristic at 270 K, and the similar value of the interaction of the PCTFE dimer with GLP is at a much higher temperature (420 K). This fact reflects the growth in thermostability of nanocomposites as compared to the polymer itself.","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":" 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139140628","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}
Regulation of enterohepatic circulation of bile acids in human body is actual task to overcome cardiovascular diseases. The aim of this work was to create biocompatible sorbents with improved sorption ability in relation to bile acids. Mesoporous organosilicas of MCM‑41 type with chemically grafted 3‑aminopropyl and steroid groups were obtained by sol‑gel condensation of tetraethyl orthosilicate and functional silanes in the presence of template cetyltrimethylammonium bromide. Porous structure of synthesized organosilicas was characterized by low‑temperature nitrogen adsorption–desorption and X‑ray diffraction analysis. Formation of typical for MCM‑41 hexagonal arrangement of cylindrical mesopores was confirmed. Structural parameters of synthesized silica materials were calculated. The influence of surface steroid groups on sorption ability of organosilicas was studied on example of bile salts (sodium cholate and taurocholate) in dependence of duration of contact, acidity of medium, and equilibrium concentration. Analysis of kinetic parameters of sorption estimated by Lagergren and Ho-McKey models confirms the proceeding of pseudo-second order process. The most effective sorption of sodium cholate and taurocholate was observed at pH ~ 5 and pH ~ 2, respectively, where the ovterlapping of pH regions of 3‑aminopropyl groups protonation and bile acids dissociation takes place. Analysis of experimentally obtained isotherms by use of Freundlich, Redlich‑Peterson, and BET models was carried out. It has been found that protonated amino groups are the main sorption centers of bile acids protolytic forms by synthesized aminosilica in pH range from 1 to 8. Introduction of steroid groups in surface layer at sol-gel synthesis leads to the increase of bile salts sorption due to the cooperative interactions with formation of supramolecular structures in the surface layer of organosilica. Obtained results prove prospects of usage of organosilica sorbents with surface steroid groups for regulation of bile acids content in human body.
{"title":"Influence of surface steroid groups on sorption of salts of bile acids by mesoporous organosilicas","authors":"N. V. Roik, L. Belyakova","doi":"10.15407/hftp14.03.324","DOIUrl":"https://doi.org/10.15407/hftp14.03.324","url":null,"abstract":"Regulation of enterohepatic circulation of bile acids in human body is actual task to overcome cardiovascular diseases. The aim of this work was to create biocompatible sorbents with improved sorption ability in relation to bile acids. Mesoporous organosilicas of MCM‑41 type with chemically grafted 3‑aminopropyl and steroid groups were obtained by sol‑gel condensation of tetraethyl orthosilicate and functional silanes in the presence of template cetyltrimethylammonium bromide. Porous structure of synthesized organosilicas was characterized by low‑temperature nitrogen adsorption–desorption and X‑ray diffraction analysis. Formation of typical for MCM‑41 hexagonal arrangement of cylindrical mesopores was confirmed. Structural parameters of synthesized silica materials were calculated. The influence of surface steroid groups on sorption ability of organosilicas was studied on example of bile salts (sodium cholate and taurocholate) in dependence of duration of contact, acidity of medium, and equilibrium concentration. Analysis of kinetic parameters of sorption estimated by Lagergren and Ho-McKey models confirms the proceeding of pseudo-second order process. The most effective sorption of sodium cholate and taurocholate was observed at pH ~ 5 and pH ~ 2, respectively, where the ovterlapping of pH regions of 3‑aminopropyl groups protonation and bile acids dissociation takes place. Analysis of experimentally obtained isotherms by use of Freundlich, Redlich‑Peterson, and BET models was carried out. It has been found that protonated amino groups are the main sorption centers of bile acids protolytic forms by synthesized aminosilica in pH range from 1 to 8. Introduction of steroid groups in surface layer at sol-gel synthesis leads to the increase of bile salts sorption due to the cooperative interactions with formation of supramolecular structures in the surface layer of organosilica. Obtained results prove prospects of usage of organosilica sorbents with surface steroid groups for regulation of bile acids content in human body.","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124903155","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}
The adsorption and direct calorimetric studies of the binary exchange of Ca2+ and Sr2+ cations on the Na-form of low-silica type natural clinoptilolite (Sokyrnytsya, Ukraine) were performed. The ion exchange of Ca2+ and Sr2+ cations on the Na-form of natural clinoptilolite was studied under static conditions at a solid to liquid phase ratio of 1 : 100 and a constant ionic strength of the solution of 0.1. The integral heats of ion exchange for these systems were measured using a highly sensitive Tian-Calve microcalorimeter in a special lab-made cell. Also, the ion exchange isotherms and Kielland curves were plotted, and the corrected selectivity coefficients and ion exchange constants were calculated. Changes in the integrated Gibbs free energies, enthalpies, and entropies of the ion exchange of Ca2+ and Sr2+ cations on the Na-form of clinoptilolite were calculated in entire range of the substitutions of the exchange complex. The thermodynamic parameters of incomplete ion exchange were analyzed in terms of the crystal structure of the zeolite. In addition, the state of exchangeable cations in the channels of clinoptilolite was described in detail. It is shown that structural heterogeneities of cation-substituted forms of clinoptilolite are clearly reflected in the dependence of thermodynamic functions on the degree of exchange, and significant differences are observed between the exchange of Ca2+ and Sr2+ cations that could not be described by standard thermodynamic values. Although the isotherms of ion exchange have a convex shape, the Na-form of clinoptilolite does not show any thermodynamic affinity to Ca2+ cations. This ion exchange reaction is accompanied by positive enthalpy changes in all range of substitutions of the exchange complex. At the same time, thermodynamic selectivity toward Sr2+ cations was observed for 40 % of the zeolite exchange centers, and the exchange is accompanied by minor exothermic effects in the range of small substitutions, and the ion exchange isotherm has σ-like form. In general, the thermodynamic affinity of the Na-form of clinoptilolite to the studied metal ions under conditions of incomplete exchange is ordered as following hydration energy trends in the case of the lyotropic properties among alkaline earth metals. Thus, the experimental thermodynamic characteristics of ion exchange equilibria could be a reliable support for the practical using of natural clinoptilolite.
{"title":"Thermodynamics of the ion exchange of Ca2+ and Sr2+ cations on Na-form of natural clinoptilolite","authors":"D. A. Krysenko, Yu. A. Таrasevich, V. Demchenko","doi":"10.15407/hftp14.03.358","DOIUrl":"https://doi.org/10.15407/hftp14.03.358","url":null,"abstract":"The adsorption and direct calorimetric studies of the binary exchange of Ca2+ and Sr2+ cations on the Na-form of low-silica type natural clinoptilolite (Sokyrnytsya, Ukraine) were performed. The ion exchange of Ca2+ and Sr2+ cations on the Na-form of natural clinoptilolite was studied under static conditions at a solid to liquid phase ratio of 1 : 100 and a constant ionic strength of the solution of 0.1. The integral heats of ion exchange for these systems were measured using a highly sensitive Tian-Calve microcalorimeter in a special lab-made cell. Also, the ion exchange isotherms and Kielland curves were plotted, and the corrected selectivity coefficients and ion exchange constants were calculated. Changes in the integrated Gibbs free energies, enthalpies, and entropies of the ion exchange of Ca2+ and Sr2+ cations on the Na-form of clinoptilolite were calculated in entire range of the substitutions of the exchange complex. The thermodynamic parameters of incomplete ion exchange were analyzed in terms of the crystal structure of the zeolite. In addition, the state of exchangeable cations in the channels of clinoptilolite was described in detail. It is shown that structural heterogeneities of cation-substituted forms of clinoptilolite are clearly reflected in the dependence of thermodynamic functions on the degree of exchange, and significant differences are observed between the exchange of Ca2+ and Sr2+ cations that could not be described by standard thermodynamic values. Although the isotherms of ion exchange have a convex shape, the Na-form of clinoptilolite does not show any thermodynamic affinity to Ca2+ cations. This ion exchange reaction is accompanied by positive enthalpy changes in all range of substitutions of the exchange complex. At the same time, thermodynamic selectivity toward Sr2+ cations was observed for 40 % of the zeolite exchange centers, and the exchange is accompanied by minor exothermic effects in the range of small substitutions, and the ion exchange isotherm has σ-like form. In general, the thermodynamic affinity of the Na-form of clinoptilolite to the studied metal ions under conditions of incomplete exchange is ordered as following hydration energy trends in the case of the lyotropic properties among alkaline earth metals. Thus, the experimental thermodynamic characteristics of ion exchange equilibria could be a reliable support for the practical using of natural clinoptilolite.","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129567613","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}
V. Goncharuk, A. S. Makarov, L. Dubrovina, I. M. Kosygina, I. Kruchko
Efficient and environmentally friendly means for fire extinguishing can reduce extreme economic losses from fires and protect people's lives and property. A separate problem is extinguishing oil products on the water surface. Dry water is a new type of environmentally friendly fire extinguishing agent. It is a powder with a water content of more than 90 %, so it has excellent fire extinguishing properties. The purpose of this work was to obtain dry water fire extinguishing powders based on pyrogenic hydrophobic methyl silica with bentonite and to study their fire extinguishing properties in case of extinguishing gasoline on water surface. To obtain dry water fire extinguishing powders, there were used distilled water, Dashukovsky bentonite (Ukraine), and pyrogenic methyl silica (AM-300 brand, Ssp = 300 m2/g, particle size 5–7 nm) (Kalush, Ukraine). Dry water fire extinguishing powder was prepared by mixing the components at a speed of 15000 rpm for 10 s. Were made samples containing 10 wt. % methyl silica, 3, 6, 10, and 15 wt. % bentonite and the corresponding amount of water. The bulk density was 0.423, 0.453, 0.459, and 0.464 g/cm3 for samples of 3, 6, 10, and 15 wt. % bentonite, respectively. Optical microscopy has shown that the particles of the dry water powder have a clearly visible core-shell structure. Dry water fire extinguishing powder is a polydisperse system - most of the particles are single fine particles with a size of 1 micron or less, and there are also agglomerates with a size of more than 5 microns. As a result of the mechanical destruction of individual bentonite particles during high-speed mixing of components, bentonite particles are destroyed, therefore, individual bentonite particles are surrounded by a hydrophobic-hydrophilic mixture of hydrophobic silica nanoparticles and bentonite nanoparticles formed during exfoliation. The study of the fire-extinguishing properties of the dry water powder was carried out by spraying it onto a layer of burning gasoline A92 on water surface. The time to complete extinguishing of the fire and the consumption of the substance per unit area of burning were determined. It has been determined that the time for extinguishing gasoline and the consumption of dry water fire extinguishing powder for extinguishing it depend on the concentration of bentonite and are for 3, 6, 10, and 15 wt. % 9, 7, 6, and 9 s and 0.333, 0.309, 0.284, and 0.260 g/cm3, respectively. The developed dry water fire extinguishing powders are environmentally friendly, have good fire extinguishing properties, and can be used to extinguish oil products on the surface of water bodies.
{"title":"Dry water fire extinguishing agents with bentonite","authors":"V. Goncharuk, A. S. Makarov, L. Dubrovina, I. M. Kosygina, I. Kruchko","doi":"10.15407/hftp14.03.443","DOIUrl":"https://doi.org/10.15407/hftp14.03.443","url":null,"abstract":"Efficient and environmentally friendly means for fire extinguishing can reduce extreme economic losses from fires and protect people's lives and property. A separate problem is extinguishing oil products on the water surface. Dry water is a new type of environmentally friendly fire extinguishing agent. It is a powder with a water content of more than 90 %, so it has excellent fire extinguishing properties. The purpose of this work was to obtain dry water fire extinguishing powders based on pyrogenic hydrophobic methyl silica with bentonite and to study their fire extinguishing properties in case of extinguishing gasoline on water surface. To obtain dry water fire extinguishing powders, there were used distilled water, Dashukovsky bentonite (Ukraine), and pyrogenic methyl silica (AM-300 brand, Ssp = 300 m2/g, particle size 5–7 nm) (Kalush, Ukraine). Dry water fire extinguishing powder was prepared by mixing the components at a speed of 15000 rpm for 10 s. Were made samples containing 10 wt. % methyl silica, 3, 6, 10, and 15 wt. % bentonite and the corresponding amount of water. The bulk density was 0.423, 0.453, 0.459, and 0.464 g/cm3 for samples of 3, 6, 10, and 15 wt. % bentonite, respectively. Optical microscopy has shown that the particles of the dry water powder have a clearly visible core-shell structure. Dry water fire extinguishing powder is a polydisperse system - most of the particles are single fine particles with a size of 1 micron or less, and there are also agglomerates with a size of more than 5 microns. As a result of the mechanical destruction of individual bentonite particles during high-speed mixing of components, bentonite particles are destroyed, therefore, individual bentonite particles are surrounded by a hydrophobic-hydrophilic mixture of hydrophobic silica nanoparticles and bentonite nanoparticles formed during exfoliation. The study of the fire-extinguishing properties of the dry water powder was carried out by spraying it onto a layer of burning gasoline A92 on water surface. The time to complete extinguishing of the fire and the consumption of the substance per unit area of burning were determined. It has been determined that the time for extinguishing gasoline and the consumption of dry water fire extinguishing powder for extinguishing it depend on the concentration of bentonite and are for 3, 6, 10, and 15 wt. % 9, 7, 6, and 9 s and 0.333, 0.309, 0.284, and 0.260 g/cm3, respectively. The developed dry water fire extinguishing powders are environmentally friendly, have good fire extinguishing properties, and can be used to extinguish oil products on the surface of water bodies.","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117295568","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}
Using a variational method within the framework of the effective mass approximation, using a triangular coordinate system of an electron, hole, and exciton moving in a titanium dioxide quantum dot, the exciton energy spectrum was obtained as a function of the radius a of the quantum dot. The variational wave function of the exciton contained factors that took into account the motion of an electron and a hole in a potential well of infinite depth of a quantum dot, as well as the form of a hydrogen-like wave function. It is shown that the occurrence of an exciton in a quantum dot has a threshold character. An exciton, as a bound state of an electron and a hole, is formed starting from a certain critical radius ac, the value of which exceeds the Bohr radius of the exciton in titanium dioxide. The exciton energy levels are located in the band gap of the titanium dioxide quantum dot. In this case, with an increase in the radius a of the quantum dot (so that a≥ac), a band of exciton states appears in the band gap of the titanium dioxide quantum dot. The mechanism for the formation of optical absorption spectra in nanosystems containing titanium dioxide nanocrystals are presented. It is found that the optical absorption of anatase NC, which was observed under the experimental conditions, was due to the appearance of an exciton in the NC. Using the variational calculation of the energy spectrum of an exciton in NC, the position of the absorption peak of NC anatase was determined. This absorption peak differs slightly from the absorption peak, which was obtained in the experimental work.
{"title":"Optical absorption by titanium dioxide nanocrystals","authors":"S. I. Pokytnii, A. D. Terets","doi":"10.15407/hftp14.03.383","DOIUrl":"https://doi.org/10.15407/hftp14.03.383","url":null,"abstract":"Using a variational method within the framework of the effective mass approximation, using a triangular coordinate system of an electron, hole, and exciton moving in a titanium dioxide quantum dot, the exciton energy spectrum was obtained as a function of the radius a of the quantum dot. The variational wave function of the exciton contained factors that took into account the motion of an electron and a hole in a potential well of infinite depth of a quantum dot, as well as the form of a hydrogen-like wave function. It is shown that the occurrence of an exciton in a quantum dot has a threshold character. An exciton, as a bound state of an electron and a hole, is formed starting from a certain critical radius ac, the value of which exceeds the Bohr radius of the exciton in titanium dioxide. The exciton energy levels are located in the band gap of the titanium dioxide quantum dot. In this case, with an increase in the radius a of the quantum dot (so that a≥ac), a band of exciton states appears in the band gap of the titanium dioxide quantum dot. The mechanism for the formation of optical absorption spectra in nanosystems containing titanium dioxide nanocrystals are presented. It is found that the optical absorption of anatase NC, which was observed under the experimental conditions, was due to the appearance of an exciton in the NC. Using the variational calculation of the energy spectrum of an exciton in NC, the position of the absorption peak of NC anatase was determined. This absorption peak differs slightly from the absorption peak, which was obtained in the experimental work.","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129605171","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}
O. Zolotarenko, E. Rudakova, A. Zolotarenko, N. Shvachko, N. Akhanova, M. Ualkhanova, D. V. Schur, V. Lavrenko, M. Gabdullin, Yuriy I. Zhirko, A. Zolotarenko, Yuriy O. Tarasenko, M. Chymbai, O. Havryliuk
The preparation of ceramic composites based on metal nanopowders allows us to change significantly the thermal characteristics of the ceramic matrix, which is important for the creation of heat-conducting ceramics technology. The work establishes the most efficient method of obtaining nickel nanopowder on a “P-5848” potentiostat by electrolysis of nickel sulfate (NiSO4) with the addition of boric acid (H3BO3), thiourea ((NH4)2CS) and nickel(II) chloride (NiCl2). The synthesis of Ni nanopowder was carried out at a current density from 1.0 to 3.3 A/dm2 and at a temperature of 45–65 °C, where a platinum (Pt) plate was chosen as an anode, and the cathode was specially made of especially pure aluminum (Al). The results of the study showed the synthesis of Ni nanopowder with a size of 55 nm in the form of thin scales. Electrochemical reactions at the cathode and anode are also considered in the work. Several successful experiments were also carried out in the work, which made it possible to develop an economically profitable technology for the synthesis of copper nanopowder by the electrolysis method at 13.3 ampere-hours of current per 1 dm2 of the anode surface at a relatively low temperature of the copper sulfate solution (CuSO4). Copper nanopowder is removed to the bottom of the bath from the anode by impact shaking. An equally successful experiment was carried out, where the cathode was in the form of several copper plates at the distance of 0.8 cm from each other with a voltage between them of 0.775 V, and a current density of 15.3 A/dm2 at the temperature of 54 °С in an electrolyte with 45 % H2SO4, 8 % Na2SO4 and 4 % CuSO4. The work contains tables with initial and final data of all experiments on the synthesis of nanopowders by the electrolysis method.
基于金属纳米粉末的陶瓷复合材料的制备使我们能够显著改变陶瓷基体的热特性，这对于创造导热陶瓷技术是重要的。本文建立了在P-5848恒电位器上用硼酸(H3BO3)、硫脲(NH4)2CS和氯化镍(NiCl2)电解硫酸镍(NiSO4)获得纳米镍粉的最有效方法。在电流密度为1.0 ~ 3.3 a /dm2，温度为45 ~ 65℃的条件下，以铂(Pt)板为阳极，以特纯铝(Al)为阴极，合成了Ni纳米粉体。研究结果表明，合成的Ni纳米粉体尺寸为55 nm，呈薄片状。在工作中还考虑了阴极和阳极的电化学反应。在工作中还进行了几次成功的实验，这使得在相对较低的硫酸铜溶液(CuSO4)温度下，以每1 dm2的13.3安培小时电流的电解方法合成纳米铜粉末成为可能。铜纳米粉通过冲击震动从阳极移至槽底。在一个同样成功的实验中，阴极以几个铜板的形式存在，它们之间的距离为0.8 cm，它们之间的电压为0.775 V，电流密度为15.3 a /dm2，温度为54°С，电解质为45% H2SO4, 8% Na2SO4和4% CuSO4。该工作包含了用电解法合成纳米粉末的所有实验的初始和最终数据的表格。
{"title":"Synthesis of Ni and Cu nanopowders by electrolysis","authors":"O. Zolotarenko, E. Rudakova, A. Zolotarenko, N. Shvachko, N. Akhanova, M. Ualkhanova, D. V. Schur, V. Lavrenko, M. Gabdullin, Yuriy I. Zhirko, A. Zolotarenko, Yuriy O. Tarasenko, M. Chymbai, O. Havryliuk","doi":"10.15407/hftp14.03.393","DOIUrl":"https://doi.org/10.15407/hftp14.03.393","url":null,"abstract":"The preparation of ceramic composites based on metal nanopowders allows us to change significantly the thermal characteristics of the ceramic matrix, which is important for the creation of heat-conducting ceramics technology. The work establishes the most efficient method of obtaining nickel nanopowder on a “P-5848” potentiostat by electrolysis of nickel sulfate (NiSO4) with the addition of boric acid (H3BO3), thiourea ((NH4)2CS) and nickel(II) chloride (NiCl2). The synthesis of Ni nanopowder was carried out at a current density from 1.0 to 3.3 A/dm2 and at a temperature of 45–65 °C, where a platinum (Pt) plate was chosen as an anode, and the cathode was specially made of especially pure aluminum (Al). The results of the study showed the synthesis of Ni nanopowder with a size of 55 nm in the form of thin scales. Electrochemical reactions at the cathode and anode are also considered in the work. Several successful experiments were also carried out in the work, which made it possible to develop an economically profitable technology for the synthesis of copper nanopowder by the electrolysis method at 13.3 ampere-hours of current per 1 dm2 of the anode surface at a relatively low temperature of the copper sulfate solution (CuSO4). Copper nanopowder is removed to the bottom of the bath from the anode by impact shaking. An equally successful experiment was carried out, where the cathode was in the form of several copper plates at the distance of 0.8 cm from each other with a voltage between them of 0.775 V, and a current density of 15.3 A/dm2 at the temperature of 54 °С in an electrolyte with 45 % H2SO4, 8 % Na2SO4 and 4 % CuSO4. The work contains tables with initial and final data of all experiments on the synthesis of nanopowders by the electrolysis method.","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":"114 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127173908","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}
Сreation of new therapeutic materials based on nucleic acids encourages the combination of the latter with materials capable of adsorbing them. One of the most promising materials for such purposes is nanocrystalline titanium dioxide due to its low toxicity, stability of its physical and chemical parameters, and high biocompatibility. Accordingly, understanding the nature of the interaction of the surface of titanium oxide with biologically active substances is a very important issue. It is also always a relevant question whether the biopolymer immobilized on the surface of a solid remains capable of serving as a reservoir for drug delivery or a tool for the treatment of a particular disease. The aim of the work was to investigate the interaction of the biologically active substance rivanol with the surface of DNA-containing titanium dioxide. It has been found that prior adsorption of deoxyribonucleic acid on the surface of titanium dioxide does not prevent its interaction with rivanol, which was confirmed by the methods of electron spectroscopy, atomic force and scanning electron microscopy. The mode of interaction of rivanol with deoxyribonucleic acid depends on the ratio of their concentrations and can be either intercalated or semi-intercalated, and electrostatic. Based on the calculated thermodynamic characteristics, the process of interaction of deoxyribonucleic acid adsorbed on the surface of a solid carrier is arbitrary and occurs by an ion exchange mechanism. These hybrid organo-mineral sorbents can serve as model structures for research in biotechnological fields, be used for the development of new methods of drug or gene delivery, reservoir systems at a molecular level, and serve as biocompatible carriers. The creation of organo-mineral sorbents, which combine nucleic acids and metal oxides, contributes to the stabilization of such systems and expands the scope of their possible application in medicine and biotechnology, increasing their target specificity.
{"title":"Interaction of rivanol with molecules of deoxyribonucleic acid (DNA) sorbed onto nanocrystalline titania surface","authors":"O. Markitan, N. N. Vlasova, Y. Sheludko","doi":"10.15407/hftp14.03.341","DOIUrl":"https://doi.org/10.15407/hftp14.03.341","url":null,"abstract":"Сreation of new therapeutic materials based on nucleic acids encourages the combination of the latter with materials capable of adsorbing them. One of the most promising materials for such purposes is nanocrystalline titanium dioxide due to its low toxicity, stability of its physical and chemical parameters, and high biocompatibility. Accordingly, understanding the nature of the interaction of the surface of titanium oxide with biologically active substances is a very important issue. It is also always a relevant question whether the biopolymer immobilized on the surface of a solid remains capable of serving as a reservoir for drug delivery or a tool for the treatment of a particular disease. The aim of the work was to investigate the interaction of the biologically active substance rivanol with the surface of DNA-containing titanium dioxide. It has been found that prior adsorption of deoxyribonucleic acid on the surface of titanium dioxide does not prevent its interaction with rivanol, which was confirmed by the methods of electron spectroscopy, atomic force and scanning electron microscopy. The mode of interaction of rivanol with deoxyribonucleic acid depends on the ratio of their concentrations and can be either intercalated or semi-intercalated, and electrostatic. Based on the calculated thermodynamic characteristics, the process of interaction of deoxyribonucleic acid adsorbed on the surface of a solid carrier is arbitrary and occurs by an ion exchange mechanism. These hybrid organo-mineral sorbents can serve as model structures for research in biotechnological fields, be used for the development of new methods of drug or gene delivery, reservoir systems at a molecular level, and serve as biocompatible carriers. The creation of organo-mineral sorbents, which combine nucleic acids and metal oxides, contributes to the stabilization of such systems and expands the scope of their possible application in medicine and biotechnology, increasing their target specificity.","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114277247","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}
V. Gun'ko, Y. Sementsov, L. S. Andriyko, Yurii Nychyporuk, O. Oranska, O. K. Matkovsky, Yulia Grebel’na, B. Charmas, J. Skubiszewska-Zięba, M. Kartel
Various 2D carbons demonstrate significant effects of surface oxidation, heating, suspending–drying, cryogelation, swelling, and adsorption of polar and nonpolar compounds on the morphological, structural, and textural characteristics. Heating at 120–150 °C could result in collapse of pores not only between carbon sheets in stacks but also between neighboring stacks; therefore, the specific surface area (SSA) decreases by a factor of 30–100 for preheated graphene oxides (GO). According to the TEM and XRD data, the GO structure is rather amorphous, since only small X-ray coherent scattering regions demonstrate a certain order giving broad XRD (001) and (002) lines. In the Raman spectra, the D line (disordered defect structures with sp3 hybridized C atoms) intensity for GO is similar to that of the G line (ordered structures with sp2 hybridized C atoms). The graphite oxide (GtO) structure, which is closer to that of graphite than that of GO, is characterized by intensive G and low D lines, and the main XRD peak at 26.4° (characteristic for graphite) is broadened similar to the XRD peak of GO at 10°. Despite the GO stacks have a tendency to collapse upon heating, the collapsed stacks can be swollen not only in water (strongly) but also in liquid nitrogen (relatively weakly). Therefore, the use of GO in aqueous media can provide great SSA values in contact with the solvent and solute molecules. This could provide high efficiency of the GO use for purification of wastewater, separation of solutes, etc. MLGO produced from natural flake graphite as a precursor (flakes < 0.2 mm in size) using a modified method of ionic hydration and freeze–drying is characterized by typical light brown color, low bulk density, flexible sheet stacks easily collapsed, but its interaction with water results in strong swelling. Interaction between the carbon sheets in preheated MLGO is strong and nonpolar molecules, such as benzene, n–decane, poorly penetrate between the sheets, i.e., intercalation adsorption is small. However, water molecules can effectively penetrate (this is rather intercalation adsorption resulting in swelling) between the sheets, but the swelling effect of water adsorbed from the gas phase could be weaker than that in the aqueous suspensions. Thus, the proposed synthesis method of MLGO using natural graphite is effective and appropriate for preparation of the materials for various practical applications.
{"title":"2D–nanostructured carbons: effects of oxidation and packing disordering","authors":"V. Gun'ko, Y. Sementsov, L. S. Andriyko, Yurii Nychyporuk, O. Oranska, O. K. Matkovsky, Yulia Grebel’na, B. Charmas, J. Skubiszewska-Zięba, M. Kartel","doi":"10.15407/hftp14.03.275","DOIUrl":"https://doi.org/10.15407/hftp14.03.275","url":null,"abstract":"Various 2D carbons demonstrate significant effects of surface oxidation, heating, suspending–drying, cryogelation, swelling, and adsorption of polar and nonpolar compounds on the morphological, structural, and textural characteristics. Heating at 120–150 °C could result in collapse of pores not only between carbon sheets in stacks but also between neighboring stacks; therefore, the specific surface area (SSA) decreases by a factor of 30–100 for preheated graphene oxides (GO). According to the TEM and XRD data, the GO structure is rather amorphous, since only small X-ray coherent scattering regions demonstrate a certain order giving broad XRD (001) and (002) lines. In the Raman spectra, the D line (disordered defect structures with sp3 hybridized C atoms) intensity for GO is similar to that of the G line (ordered structures with sp2 hybridized C atoms). The graphite oxide (GtO) structure, which is closer to that of graphite than that of GO, is characterized by intensive G and low D lines, and the main XRD peak at 26.4° (characteristic for graphite) is broadened similar to the XRD peak of GO at 10°. Despite the GO stacks have a tendency to collapse upon heating, the collapsed stacks can be swollen not only in water (strongly) but also in liquid nitrogen (relatively weakly). Therefore, the use of GO in aqueous media can provide great SSA values in contact with the solvent and solute molecules. This could provide high efficiency of the GO use for purification of wastewater, separation of solutes, etc. MLGO produced from natural flake graphite as a precursor (flakes < 0.2 mm in size) using a modified method of ionic hydration and freeze–drying is characterized by typical light brown color, low bulk density, flexible sheet stacks easily collapsed, but its interaction with water results in strong swelling. Interaction between the carbon sheets in preheated MLGO is strong and nonpolar molecules, such as benzene, n–decane, poorly penetrate between the sheets, i.e., intercalation adsorption is small. However, water molecules can effectively penetrate (this is rather intercalation adsorption resulting in swelling) between the sheets, but the swelling effect of water adsorbed from the gas phase could be weaker than that in the aqueous suspensions. Thus, the proposed synthesis method of MLGO using natural graphite is effective and appropriate for preparation of the materials for various practical applications.","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":"92 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114882910","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}
Double phosphates compounds may possess catalytic, magnetic, electrophysical, non-linear optical properties and are used as monocrystals or polycrystals, ceramics etc. The tailor-made synthesis of double phosphates of alkali and multivalent metals is the basis for the in-depth research and investigation of physical and chemical properties, composition and structure of the compounds to be used for the development of new materials for multi-purpose use. Episodic syntheses of compounds MI3MIІMIV(PO4)3, MI2MIIMIV(P2O7)2, MI2MII(PO3)4 and МІMІІ4(РО4)33 (where МI – Li, Na, K; МIІ – Mn, Co, Ni; MIV – Zr), were made from various starting materials by the sintering method. After all, the selection of compounds for the synthesis of compounds of this type is a rather difficult task, often impossible. A systematic approach to the selection of starting reagents, temperature regime, interaction time between components are factors that can be adjusted and operated to achieve the target. The work used the method of solid-phase synthesis, after working out the synthesis method on the “model” Na2NiZr(P2O7)2. The synthesis was carried out starting from Na2CO3, NiO, CoO, ZrO2, ammonium hydro- and dihydrogen phosphate. The synthesis of compounds was carried out based on preliminary derivatographic studies of the passage of processes according to the corresponding reaction schemes. Completeness of synthesis stages was monitored at all stages using physico-chemical research methods. The DTA method confirmed the possibility of solid-phase synthesis of complex phosphate compounds that contain several transition metals – MINi2MIV(PO4)3 (where МI – Li, Na, K; MIV – Ti, Zr, Sn). The optimal temperature conditions for obtaining a number of phosphate compounds based on various starting substances for their synthesis have been found. The synthesized compounds were investigated by X-ray diffraction, DTA and IR spectroscopy, and their complete chemical analysis was carried out. The influence of a number of factors on the conditions of production of phosphate compounds of the MINi2MIV(PO4)3 (where МI – Li, Na, K; MIV – Ti, Zr, Sn) has been found. It can be assumed that the ionic conductivity in the synthesized compounds is of the “NASICON” type, and therefore the synthesized substances can be used as functional materials with valuable electro-physical properties.
{"title":"Solid-phase synthesis of MINi2MIV(PO4)3 compounds (МI – Li, Na, K; MIV – Ti, Zr, Sn)","authors":"O. Petrenko, R. Lavrik, V. Galimova","doi":"10.15407/hftp14.03.407","DOIUrl":"https://doi.org/10.15407/hftp14.03.407","url":null,"abstract":"Double phosphates compounds may possess catalytic, magnetic, electrophysical, non-linear optical properties and are used as monocrystals or polycrystals, ceramics etc. The tailor-made synthesis of double phosphates of alkali and multivalent metals is the basis for the in-depth research and investigation of physical and chemical properties, composition and structure of the compounds to be used for the development of new materials for multi-purpose use. Episodic syntheses of compounds MI3MIІMIV(PO4)3, MI2MIIMIV(P2O7)2, MI2MII(PO3)4 and МІMІІ4(РО4)33 (where МI – Li, Na, K; МIІ – Mn, Co, Ni; MIV – Zr), were made from various starting materials by the sintering method. After all, the selection of compounds for the synthesis of compounds of this type is a rather difficult task, often impossible. A systematic approach to the selection of starting reagents, temperature regime, interaction time between components are factors that can be adjusted and operated to achieve the target. The work used the method of solid-phase synthesis, after working out the synthesis method on the “model” Na2NiZr(P2O7)2. The synthesis was carried out starting from Na2CO3, NiO, CoO, ZrO2, ammonium hydro- and dihydrogen phosphate. The synthesis of compounds was carried out based on preliminary derivatographic studies of the passage of processes according to the corresponding reaction schemes. Completeness of synthesis stages was monitored at all stages using physico-chemical research methods. The DTA method confirmed the possibility of solid-phase synthesis of complex phosphate compounds that contain several transition metals – MINi2MIV(PO4)3 (where МI – Li, Na, K; MIV – Ti, Zr, Sn). The optimal temperature conditions for obtaining a number of phosphate compounds based on various starting substances for their synthesis have been found. The synthesized compounds were investigated by X-ray diffraction, DTA and IR spectroscopy, and their complete chemical analysis was carried out. The influence of a number of factors on the conditions of production of phosphate compounds of the MINi2MIV(PO4)3 (where МI – Li, Na, K; MIV – Ti, Zr, Sn) has been found. It can be assumed that the ionic conductivity in the synthesized compounds is of the “NASICON” type, and therefore the synthesized substances can be used as functional materials with valuable electro-physical properties.","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133124546","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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