Various composites with nanosilicas, as well as with other nanooxides, and polymers are of importance from a practical point of view. Detailed textural and morphological characterization, applied here to nanosilicas treated alone and in composites with a set of polymers (poly(vinyl pyrrolidone), poly(vinyl alcohol), poly(ethylene oxide), poly(ethylene glycol), polydimethylsiloxane, and polymethylsiloxane) and proteins (egg albumin, gelatin, and ossein), could be considered as a tool to evaluate the reorganization of hierarchical structures in composites from aggregates of nanoparticles, agglomerates of aggregates, to micro and visible particles. This analysis allows one to elucidate various changes in the porosity, accessible surface area, contributions of pores of different sizes and shapes and pore walls with silica or polymer/protein depending on a set of varied factors. Collected information could be used to forecast possible characteristics and properties of various composites with nanooxides. Among the factors affecting the properties and characteristics of the composites, a type, molecular weight, and content of a polymer and treatment conditions may play an important role. The presence of a large set of the factors makes difficult analysis of the composites using simplified approaches and methods. As a whole, selection of the composition and certain conditions of the composite preparation allows one to control all the textural characteristics of the final materials. For these purposes, the characteristics should be accurately estimated with minimum possible errors using well developed and adequate methods.
{"title":"Textural characteristics and organization of composites with fumed silicas and high-molecular weight compounds","authors":"V. Gun'ko","doi":"10.15407/hftp13.02.127","DOIUrl":"https://doi.org/10.15407/hftp13.02.127","url":null,"abstract":"Various composites with nanosilicas, as well as with other nanooxides, and polymers are of importance from a practical point of view. Detailed textural and morphological characterization, applied here to nanosilicas treated alone and in composites with a set of polymers (poly(vinyl pyrrolidone), poly(vinyl alcohol), poly(ethylene oxide), poly(ethylene glycol), polydimethylsiloxane, and polymethylsiloxane) and proteins (egg albumin, gelatin, and ossein), could be considered as a tool to evaluate the reorganization of hierarchical structures in composites from aggregates of nanoparticles, agglomerates of aggregates, to micro and visible particles. This analysis allows one to elucidate various changes in the porosity, accessible surface area, contributions of pores of different sizes and shapes and pore walls with silica or polymer/protein depending on a set of varied factors. Collected information could be used to forecast possible characteristics and properties of various composites with nanooxides. Among the factors affecting the properties and characteristics of the composites, a type, molecular weight, and content of a polymer and treatment conditions may play an important role. The presence of a large set of the factors makes difficult analysis of the composites using simplified approaches and methods. As a whole, selection of the composition and certain conditions of the composite preparation allows one to control all the textural characteristics of the final materials. For these purposes, the characteristics should be accurately estimated with minimum possible errors using well developed and adequate methods.","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":"53 74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133839462","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}
H. M. Bagatskaya, R. Mazurenko, S. Makhno, P. Gorbyk
The effect of different dispersity copper iodide (CuI) particles on vital activity in an aqueous yeast suspension of organisms of the species Saccharomyces cerevisiae under anaerobic conditions under endogenous metabolism was studied by differential microcalorimetry. It has been found that an increase in the concentration of Cu+ to certain values leads to activation of the protective functions of cellular organisms, which is manifested in an increase in the energy costs of the yeast cell on the structural reorganization of the plasmolemma and possibly other membrane structures in order to counter the penetration of the bactericidal agent into the organism and its internal membrane structures. Upon reaching certain concentrations of Cu+, the yeast organism loses its original vitality, so that at its extreme values the organism completely stops its vital activity. The equilibrium concentration of Cu+ ions in aqueous solution for copper iodide nanoparticles is significantly higher in comparison with their microparticles, which is explained by the lower work function of CuI in the solution at the solid-liquid interface due to the increase in the curvature of the surface of the nanoparticle and the change in the surface tension at the interface.
{"title":"Influence of copper iodide particles of different dispersity on the fermentation activity of yeast cells Saccharomyces cerevisiae","authors":"H. M. Bagatskaya, R. Mazurenko, S. Makhno, P. Gorbyk","doi":"10.15407/hftp13.02.150","DOIUrl":"https://doi.org/10.15407/hftp13.02.150","url":null,"abstract":"The effect of different dispersity copper iodide (CuI) particles on vital activity in an aqueous yeast suspension of organisms of the species Saccharomyces cerevisiae under anaerobic conditions under endogenous metabolism was studied by differential microcalorimetry. It has been found that an increase in the concentration of Cu+ to certain values leads to activation of the protective functions of cellular organisms, which is manifested in an increase in the energy costs of the yeast cell on the structural reorganization of the plasmolemma and possibly other membrane structures in order to counter the penetration of the bactericidal agent into the organism and its internal membrane structures. Upon reaching certain concentrations of Cu+, the yeast organism loses its original vitality, so that at its extreme values the organism completely stops its vital activity. The equilibrium concentration of Cu+ ions in aqueous solution for copper iodide nanoparticles is significantly higher in comparison with their microparticles, which is explained by the lower work function of CuI in the solution at the solid-liquid interface due to the increase in the curvature of the surface of the nanoparticle and the change in the surface tension at the interface.","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115863632","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 performance of cationic dyes (methylene blue and malachite green) on barley straw modified by citric acid has been studied. Barley straw modified by citric acid is a low-cost and eco-friendly adsorbent, however the effectiveness of the adsorbent towards cationic dyes have not yet been examined. Accordingly, kinetic, equilibrium, and thermodynamic aspects of the cationic dyes adsorption from aqueous solution were studied in order to evaluate the citric acid modified barley straw efficiency. The modified barley straw was characterized versus unmodified matter using Fourier Transform Infrared spectroscopy (FT-IR). FT-IR analysis showed that modification of barley straw using citric acid allowed us to increase the number of carboxyl groups on the straw surface. Adsorption studies were conducted on a batch process, to study the effects of contact time, concentration of cationic dyes, and temperature. The results of kinetic experiments showed that adsorption process attained equilibrium within 120 and 90 min for methylene blue and malachite green, respectively, and equilibrium time for both the cationic dyes was temperature independent. The adsorption kinetics of the cationic dyes was well described by the pseudo-second order model. The equilibrium data are analyzed by the Freundlich, Langmuir, and Temkin isotherms. The experimental data of adsorption indicated more conformity with the Langmuir isotherm model for methylene blue and malachite green adsorption on the modified straw. Furthermore, the thermodynamic parameters calculated at 293–333 K showed that the adsorption of methylene blue and malachite green on the modified straw was endothermic. Negative results of ∆Go-values (between −32.1 and −24.6 kJ mol−1) indicated that the adsorption process was spontaneous at all the tested temperatures. Desorption of methylene blue and malachite green from the exhausted adsorbent was estimated using water and aqueous solutions of hydrochloric and acetic acids. Desorption efficiency follows the order: HCl > CH3COOH > H2O. The study has revealed that citric acid modified barley straw is an effective adsorbent and can be used as an alternative for more costly adsorbents used for cationic dyes removal from wastewater.
{"title":"Adsorption of cationic dyes on barley straw modified by citric acid: kinetic, equilibrium, and thermodynamic studies","authors":"L. Soldatkina, M. Yanar","doi":"10.15407/hftp13.02.197","DOIUrl":"https://doi.org/10.15407/hftp13.02.197","url":null,"abstract":"The adsorption performance of cationic dyes (methylene blue and malachite green) on barley straw modified by citric acid has been studied. Barley straw modified by citric acid is a low-cost and eco-friendly adsorbent, however the effectiveness of the adsorbent towards cationic dyes have not yet been examined. Accordingly, kinetic, equilibrium, and thermodynamic aspects of the cationic dyes adsorption from aqueous solution were studied in order to evaluate the citric acid modified barley straw efficiency. The modified barley straw was characterized versus unmodified matter using Fourier Transform Infrared spectroscopy (FT-IR). FT-IR analysis showed that modification of barley straw using citric acid allowed us to increase the number of carboxyl groups on the straw surface. Adsorption studies were conducted on a batch process, to study the effects of contact time, concentration of cationic dyes, and temperature. The results of kinetic experiments showed that adsorption process attained equilibrium within 120 and 90 min for methylene blue and malachite green, respectively, and equilibrium time for both the cationic dyes was temperature independent. The adsorption kinetics of the cationic dyes was well described by the pseudo-second order model. The equilibrium data are analyzed by the Freundlich, Langmuir, and Temkin isotherms. The experimental data of adsorption indicated more conformity with the Langmuir isotherm model for methylene blue and malachite green adsorption on the modified straw. Furthermore, the thermodynamic parameters calculated at 293–333 K showed that the adsorption of methylene blue and malachite green on the modified straw was endothermic. Negative results of ∆Go-values (between −32.1 and −24.6 kJ mol−1) indicated that the adsorption process was spontaneous at all the tested temperatures. Desorption of methylene blue and malachite green from the exhausted adsorbent was estimated using water and aqueous solutions of hydrochloric and acetic acids. Desorption efficiency follows the order: HCl > CH3COOH > H2O. The study has revealed that citric acid modified barley straw is an effective adsorbent and can be used as an alternative for more costly adsorbents used for cationic dyes removal from wastewater.","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":"120 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134273663","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}
One of the most important tasks of environmental chemistry is the development of effective methods for the extraction and chemical analysis of highly toxic oxyanions, such as nitrate, phosphate and arsenate. They enter the environment, raw materials and commercial products with waste from chemical and metallurgical industries. This problem can be solved by synthesizing selective materials that absorb anions due to the complementarity of their active centers and ions. The aim of this work is a directed chemical design of silica surface for the construction of sorption active centers with a high affinity for nitrate, orthophosphate, and orthoarsenate anions. Chemical design of β-cyclodextrin-containing supramolecular structures on the surface of granular mesoporous silica gel to obtain sorbents of highly toxic oxyanions was carried out. The structure and surface chemistry of the initial and functionalized silica gels were characterized by means of IR spectroscopy, spectrophotometry, thermogravimetric and chemical analysis, pH metry, low-temperature adsorption-desorption of nitrogen and sorption techniques. The sorption of nitrate, orthophosphate, and orthoarsenate anions from aqueous one- and multicomponent salt solutions was studied as dependent on the time and ion concentration, as well as in the cyclic sorption-desorption mode. The results obtained are interpreted using kinetic models of pseudo-first and pseudo-second order processes and the equilibrium adsorption models of Langmuir and Freundlich. The main characteristics of the specificity and selectivity of the obtained β-cyclodextrin silica gel were calculated. Conclusions are drawn regarding the possibility of using functionalized silica gel for the sorption of oxyanions from water and aqueous solutions, their concentrating, chromatographic separation, and chemical analysis.
{"title":"Role of surface chemical design in sorption specificity of functionalized silica gels","authors":"L. Belyakova, D. Lyashenko","doi":"10.15407/hftp13.01.082","DOIUrl":"https://doi.org/10.15407/hftp13.01.082","url":null,"abstract":"One of the most important tasks of environmental chemistry is the development of effective methods for the extraction and chemical analysis of highly toxic oxyanions, such as nitrate, phosphate and arsenate. They enter the environment, raw materials and commercial products with waste from chemical and metallurgical industries. This problem can be solved by synthesizing selective materials that absorb anions due to the complementarity of their active centers and ions. The aim of this work is a directed chemical design of silica surface for the construction of sorption active centers with a high affinity for nitrate, orthophosphate, and orthoarsenate anions. Chemical design of β-cyclodextrin-containing supramolecular structures on the surface of granular mesoporous silica gel to obtain sorbents of highly toxic oxyanions was carried out. The structure and surface chemistry of the initial and functionalized silica gels were characterized by means of IR spectroscopy, spectrophotometry, thermogravimetric and chemical analysis, pH metry, low-temperature adsorption-desorption of nitrogen and sorption techniques. The sorption of nitrate, orthophosphate, and orthoarsenate anions from aqueous one- and multicomponent salt solutions was studied as dependent on the time and ion concentration, as well as in the cyclic sorption-desorption mode. The results obtained are interpreted using kinetic models of pseudo-first and pseudo-second order processes and the equilibrium adsorption models of Langmuir and Freundlich. The main characteristics of the specificity and selectivity of the obtained β-cyclodextrin silica gel were calculated. Conclusions are drawn regarding the possibility of using functionalized silica gel for the sorption of oxyanions from water and aqueous solutions, their concentrating, chromatographic separation, and chemical analysis.","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129565376","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}
Interfacial phenomena at a surface of porous and highly disperse adsorbents in the systems containing strongly and weakly bound and unbound liquids depend strongly on the confined space effects. These effects as well as the temperature behavior of liquids located in pores or voids between nanoparticles depend on many factors. They are the pore size distributions, pore volume, specific surface area, surface chemistry of adsorbents, chemical structure and molecular sizes of adsorbates, accessibility of pores vs. probe molecule sizes, as well as textural instability of adsorbents. This instability can appear, e.g., as compaction of fumed oxides under action of liquid adsorbates, especially water, or due to mechanochemical activation. The aim of this study is to analyze features of the interfacial phenomena upon interactions of fumed oxides (silica, alumina, alumina/silica/titania) and porous silicas (silica gels and precipitated silica) with polar (water, dimethyl sulfoxide), weakly polar (chloroform), and nonpolar (n-decane, aromatic benzene and toluene) liquid adsorbates depending on the morphological and textural characteristics of the adsorbents, various adsorbate characteristics, and temperature. The observed effects as well as related phenomena are important because they can differently influence the efficiency of practical applications of adsorbents under various conditions (temperature, pressure, concentrations) depending on the characteristics of adsorbents and adsorbates (liquids, solvents and solutes).
{"title":"Confined space effects on various liquids interacting with fumed nanooxides and porous silicas","authors":"V. Gun'ko","doi":"10.15407/hftp13.01.047","DOIUrl":"https://doi.org/10.15407/hftp13.01.047","url":null,"abstract":"Interfacial phenomena at a surface of porous and highly disperse adsorbents in the systems containing strongly and weakly bound and unbound liquids depend strongly on the confined space effects. These effects as well as the temperature behavior of liquids located in pores or voids between nanoparticles depend on many factors. They are the pore size distributions, pore volume, specific surface area, surface chemistry of adsorbents, chemical structure and molecular sizes of adsorbates, accessibility of pores vs. probe molecule sizes, as well as textural instability of adsorbents. This instability can appear, e.g., as compaction of fumed oxides under action of liquid adsorbates, especially water, or due to mechanochemical activation. The aim of this study is to analyze features of the interfacial phenomena upon interactions of fumed oxides (silica, alumina, alumina/silica/titania) and porous silicas (silica gels and precipitated silica) with polar (water, dimethyl sulfoxide), weakly polar (chloroform), and nonpolar (n-decane, aromatic benzene and toluene) liquid adsorbates depending on the morphological and textural characteristics of the adsorbents, various adsorbate characteristics, and temperature. The observed effects as well as related phenomena are important because they can differently influence the efficiency of practical applications of adsorbents under various conditions (temperature, pressure, concentrations) depending on the characteristics of adsorbents and adsorbates (liquids, solvents and solutes).","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123840247","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}
S. Zelinskyi, N. Stryzhakova, O. Gozhenko, Y. Maletin
Electrochemical impedance spectroscopy has been used for the characterization of electric double layer capacitors also known as supercapacitors. Specific surface area and pore size distribution for supercapacitor electrode materials and the results of impedance spectroscopy measurements for two types of commercially available nanoporous activated carbons and two graphene-type materials have been studied and compared with the results obtained from cyclic voltammetry and galvanostatic charge-discharge cycling the supercapacitor prototypes in different voltage ranges and at different current densities. It has been found that the results for the characteristics of studied supercapacitor prototypes differ insignificantly if they were obtained by different methods, while all three research methods have shown the advantage of materials with nanoporous activated carbon over materials of the graphene type. Besides, according to the data obtained by measuring impedance at low frequencies the deviations from ideal capacitive behaviour are more significant in case of graphene-type materials. Comparison of the three research methods used in this work shows that the method of impedance spectroscopy makes it possible to obtain the most complete and reliable information on the performance characteristics of the supercapacitor system, since not only the capacitance and resistance values, but their frequency dependence, as well as deviations (in degrees) from the purely capacitive vertical line at Nyquist plots and capacitance dissipation can be determined and taken into consideration.
{"title":"How the electrochemical impedance spectroscopy can deepen the understanding of supercapacitor performance","authors":"S. Zelinskyi, N. Stryzhakova, O. Gozhenko, Y. Maletin","doi":"10.15407/hftp13.01.070","DOIUrl":"https://doi.org/10.15407/hftp13.01.070","url":null,"abstract":"Electrochemical impedance spectroscopy has been used for the characterization of electric double layer capacitors also known as supercapacitors. Specific surface area and pore size distribution for supercapacitor electrode materials and the results of impedance spectroscopy measurements for two types of commercially available nanoporous activated carbons and two graphene-type materials have been studied and compared with the results obtained from cyclic voltammetry and galvanostatic charge-discharge cycling the supercapacitor prototypes in different voltage ranges and at different current densities. It has been found that the results for the characteristics of studied supercapacitor prototypes differ insignificantly if they were obtained by different methods, while all three research methods have shown the advantage of materials with nanoporous activated carbon over materials of the graphene type. Besides, according to the data obtained by measuring impedance at low frequencies the deviations from ideal capacitive behaviour are more significant in case of graphene-type materials. Comparison of the three research methods used in this work shows that the method of impedance spectroscopy makes it possible to obtain the most complete and reliable information on the performance characteristics of the supercapacitor system, since not only the capacitance and resistance values, but their frequency dependence, as well as deviations (in degrees) from the purely capacitive vertical line at Nyquist plots and capacitance dissipation can be determined and taken into consideration.","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132392549","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}
A. Kasumov, A. Dmitriev, M. Radchenko, A. E. Baybara, O. Bykov, K. A. Korotkov, V. Karavaeva, K. O. Vyshnevska, O. Olifan, A. Ievtushenko
It has been shown by the anomalous Hall effect method that upon contact of layers of iron group metal (Ni) and REM oxide (Gd2O3) nanosized films, an increase by 15–35 % in the magnetization of the ferromagnetic metal is observed. Such an increase does not require energy consumption and the use of amplifying equipment, is very promising for nanotechnology. The enhancement of magnetization is due to the appearance in the contact region of the exchange f–d interaction between atoms with empty d– and f–electron shells that are parts of the layers. The exchange interaction stimulates the ordering of the magnetic structure of the ferromagnetic metal and an increase in its magnetization. The possibility of exchange f–d interaction in the region of contact of layers of metals of the iron group and REM oxides was confirmed by the method of electronic paramagnetic resonance in our previous studies. This paper also shows the lack of influence on the growth of magnetization of other possible mechanisms due to the difference in the parameters of the crystal lattice, resistance, magnetic and termomagnetic properties of the contacting layers. A mathematical connection is found of the potential of Hall contacts and additional magnetization stimulated by the exchange f–d interaction. Using this relationship, the mechanism of the effect of an external magnetic field on additional magnetization had revealed. It is shown that this magnetization depends on the ratio of the thicknesses of the Ni and Gd2O3 layers. It has been found that the vector of this magnetization is directed from the Gd2O3 layer to the Ni layer.
{"title":"Anomalous Hall effect in a double-layer Ni / Gd2O3 nanosized films","authors":"A. Kasumov, A. Dmitriev, M. Radchenko, A. E. Baybara, O. Bykov, K. A. Korotkov, V. Karavaeva, K. O. Vyshnevska, O. Olifan, A. Ievtushenko","doi":"10.15407/hftp13.01.105","DOIUrl":"https://doi.org/10.15407/hftp13.01.105","url":null,"abstract":"It has been shown by the anomalous Hall effect method that upon contact of layers of iron group metal (Ni) and REM oxide (Gd2O3) nanosized films, an increase by 15–35 % in the magnetization of the ferromagnetic metal is observed. Such an increase does not require energy consumption and the use of amplifying equipment, is very promising for nanotechnology. The enhancement of magnetization is due to the appearance in the contact region of the exchange f–d interaction between atoms with empty d– and f–electron shells that are parts of the layers. The exchange interaction stimulates the ordering of the magnetic structure of the ferromagnetic metal and an increase in its magnetization. The possibility of exchange f–d interaction in the region of contact of layers of metals of the iron group and REM oxides was confirmed by the method of electronic paramagnetic resonance in our previous studies. This paper also shows the lack of influence on the growth of magnetization of other possible mechanisms due to the difference in the parameters of the crystal lattice, resistance, magnetic and termomagnetic properties of the contacting layers. A mathematical connection is found of the potential of Hall contacts and additional magnetization stimulated by the exchange f–d interaction. Using this relationship, the mechanism of the effect of an external magnetic field on additional magnetization had revealed. It is shown that this magnetization depends on the ratio of the thicknesses of the Ni and Gd2O3 layers. It has been found that the vector of this magnetization is directed from the Gd2O3 layer to the Ni layer.","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":"77 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130853956","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}
Yu. V. Таmarkina, V. Anishchenko, A. Red'ko, V. Kucherenko
The aim of the work is to compare the microporous structure characteristics of activated carbons (ACs) prepared from coals of different coals rank (CR) by alkaline activation (RKOH = 1 g/g, 800 °C) and to determine the ACs capability to adsorb phenol and 4-chlorophenol from aqueous solutions. Starting materials are coals with increasing carbon content (Cdaf = 80.0–95.6 %) selected as a CR criterion. ACs were obtained in argon in three stages: 1) thermoprogrammed heating (4 grad/min) to 800 °С; 2) isothermal exposure 1 h; 3) cooling, washing from alkali and drying. Based on low-temperature (77 K) nitrogen adsorption-desorption isotherms, integral and differential dependences of the specific surface area S (m2/g) and pore volume V (cm3/g) on the average pore diameter (D, nm) were calculated. They were used to define volumes of ultramicropores (Vumi), supermicropores (Vsmi) and micropores (Vmi). The total pore volume Vt was calculated from the nitrogen amount adsorbed at a relative pressure p/p0 ~ 1.0. The S values of ultramicropores (Sumi), supermicropores (Ssmi) and micropores (Smi) were similarly determined. The volumes and specific surfaces of different categories of pores were found to decrease with CR increase: volume Vt – from 0.59 to 0.23 cm3/g; Vmi – from 0.51 to 0.17 cm3/g; the ultramicropores volume – from 0.31 cm3/g to zero in anthracite AC. The supermicropores volume is almost independent on CR and varies in the wide range Vsmi = 0.15–0.22 cm3/h. The specific surface area is the maximum (S = 1547 m2/g) in AC from the coal of the lowest CR and decreases with coal metamorphism up to 322 m2/g. The micropores surfaces make dominant contributions to the S values: its portion is 94.7–99.4 %. For all ACs, the adsorption of phenol (Ph) and 4-chlorophenol (CPh) from aqueous solutions at 25 °C was studied. Adsorption kinetics and isotherms are best described by the pseudo-second order model and the Langmuir model (R2 ≥ 0.998). With increasing CR, the maximum adsorption capacities decrease from 3.113 to 1.498 mmol/g (Ph) and from 3.9 to 2.1 mmol/g (CPh), that is approximately ~2 times when the specific surface area decreases by ~5 times. The Ph and CPh specific capacities, characterizing the adsorption capacity of 1 m2 of surface, change little at Cdaf≤86 %, but markedly increase (2.3–2.5 times) for anthracite AСs. The Ph and CPh capacitances were determined to increase linearly (R2 ≥ 0.966) with increasing ACs specific surface area. Similar dependences were found on the Sumi and Smi parameters. The phenols were concluded to be equally adsorbed on the surface of pores of any size. A general trend was found for ACs from hard coals and anthracite: an increase in CR reduces the ACs microporosity and surface, decreases Ph and CPh capacities but increases specific capacities, i.e. concentrations of surface adsorption centers. The Ph and CPh adsorption was accepted to include the interaction of π-electrons of phenolic rings and π-electrons of graphene l
{"title":"Alkali activated coals. Microporous structure and capability to adsorb phenol compounds","authors":"Yu. V. Таmarkina, V. Anishchenko, A. Red'ko, V. Kucherenko","doi":"10.15407/hftp13.01.111","DOIUrl":"https://doi.org/10.15407/hftp13.01.111","url":null,"abstract":"The aim of the work is to compare the microporous structure characteristics of activated carbons (ACs) prepared from coals of different coals rank (CR) by alkaline activation (RKOH = 1 g/g, 800 °C) and to determine the ACs capability to adsorb phenol and 4-chlorophenol from aqueous solutions. Starting materials are coals with increasing carbon content (Cdaf = 80.0–95.6 %) selected as a CR criterion. ACs were obtained in argon in three stages: 1) thermoprogrammed heating (4 grad/min) to 800 °С; 2) isothermal exposure 1 h; 3) cooling, washing from alkali and drying. Based on low-temperature (77 K) nitrogen adsorption-desorption isotherms, integral and differential dependences of the specific surface area S (m2/g) and pore volume V (cm3/g) on the average pore diameter (D, nm) were calculated. They were used to define volumes of ultramicropores (Vumi), supermicropores (Vsmi) and micropores (Vmi). The total pore volume Vt was calculated from the nitrogen amount adsorbed at a relative pressure p/p0 ~ 1.0. The S values of ultramicropores (Sumi), supermicropores (Ssmi) and micropores (Smi) were similarly determined. The volumes and specific surfaces of different categories of pores were found to decrease with CR increase: volume Vt – from 0.59 to 0.23 cm3/g; Vmi – from 0.51 to 0.17 cm3/g; the ultramicropores volume – from 0.31 cm3/g to zero in anthracite AC. The supermicropores volume is almost independent on CR and varies in the wide range Vsmi = 0.15–0.22 cm3/h. The specific surface area is the maximum (S = 1547 m2/g) in AC from the coal of the lowest CR and decreases with coal metamorphism up to 322 m2/g. The micropores surfaces make dominant contributions to the S values: its portion is 94.7–99.4 %. For all ACs, the adsorption of phenol (Ph) and 4-chlorophenol (CPh) from aqueous solutions at 25 °C was studied. Adsorption kinetics and isotherms are best described by the pseudo-second order model and the Langmuir model (R2 ≥ 0.998). With increasing CR, the maximum adsorption capacities decrease from 3.113 to 1.498 mmol/g (Ph) and from 3.9 to 2.1 mmol/g (CPh), that is approximately ~2 times when the specific surface area decreases by ~5 times. The Ph and CPh specific capacities, characterizing the adsorption capacity of 1 m2 of surface, change little at Cdaf≤86 %, but markedly increase (2.3–2.5 times) for anthracite AСs. The Ph and CPh capacitances were determined to increase linearly (R2 ≥ 0.966) with increasing ACs specific surface area. Similar dependences were found on the Sumi and Smi parameters. The phenols were concluded to be equally adsorbed on the surface of pores of any size. A general trend was found for ACs from hard coals and anthracite: an increase in CR reduces the ACs microporosity and surface, decreases Ph and CPh capacities but increases specific capacities, i.e. concentrations of surface adsorption centers. The Ph and CPh adsorption was accepted to include the interaction of π-electrons of phenolic rings and π-electrons of graphene l","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":"292 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122718676","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. Turov, P. Gorbyk, T. Krupska, S. P. Turanska, E. V. Koval, N. Cheremshenko
The aim of the work was to study the peculiarities of interaction of the surface of bacterial lectin of Bacillus subtilis IMB B-7724 inthe native state and under different model conditions with water molecules by 1 H NMR; to create a composite system based on the studied lectin, in which the protein molecule is minimally affected by the surface of the carrier, because protein molecules are capable to bind a significant amount of water localized in the spaces between the polymer chains. A method of “dry” immobilization of bacterial lectin on the surface of hydrophobic silica has been developed. Hydration of native lectin and lectin fixed on the surface of hydrophobic silica AM-1-175 was studied by low-temperature 1 H NMR spectroscopy. It has been shown that the immobilization of lectin on the surface of AM1 is accompanied by an increase in the interfacial energy gS from 4.1 to 5.2 J/g. This is due to an increase in the concentration of strongly bound water. Analysis of changes in the distributions of radii R of clusters of adsorbed water allows us to state that in water adsorbed by native lectin, there are two main maxima at R = 1 and 3 nm. In the immobilized state, the maximum at R = 1 nm is present in both types of water (of different order), but the second maximum is observed only for more ordered associates. Chloroform medium slightly reduces the binding energy of water to native lectin molecules (from 4.3 to 4.1 J/g), but in the case of immobilized lectin in CDCl3 medium, the value of ΣgS increases from 5.2 to 7.4 J/g. That is, the weakly polar medium promotes to increase in the interaction of water with interfaces, which is manifested in a relative increase in the number of water clusters of smaller size (Fig. 4). It should be noted that weakly associated forms of water (signal 3) are also represented by several types of clusters that have a radius in the range R = 1–10 nm, and their size distribution changes significantly during immobilization of lectin on the surface of AM1. Probably, weakly associated types of water are formed both in cavities, between polymer chains of protein molecules, and on the surface of AM1, free of protein.
{"title":"Hydration of bacterial lectin in native state and after immobilization on surface of hydrophobic silica","authors":"V. Turov, P. Gorbyk, T. Krupska, S. P. Turanska, E. V. Koval, N. Cheremshenko","doi":"10.15407/hftp13.01.060","DOIUrl":"https://doi.org/10.15407/hftp13.01.060","url":null,"abstract":"The aim of the work was to study the peculiarities of interaction of the surface of bacterial lectin of Bacillus subtilis IMB B-7724 inthe native state and under different model conditions with water molecules by 1 H NMR; to create a composite system based on the studied lectin, in which the protein molecule is minimally affected by the surface of the carrier, because protein molecules are capable to bind a significant amount of water localized in the spaces between the polymer chains. A method of “dry” immobilization of bacterial lectin on the surface of hydrophobic silica has been developed. Hydration of native lectin and lectin fixed on the surface of hydrophobic silica AM-1-175 was studied by low-temperature 1 H NMR spectroscopy. It has been shown that the immobilization of lectin on the surface of AM1 is accompanied by an increase in the interfacial energy gS from 4.1 to 5.2 J/g. This is due to an increase in the concentration of strongly bound water. Analysis of changes in the distributions of radii R of clusters of adsorbed water allows us to state that in water adsorbed by native lectin, there are two main maxima at R = 1 and 3 nm. In the immobilized state, the maximum at R = 1 nm is present in both types of water (of different order), but the second maximum is observed only for more ordered associates. Chloroform medium slightly reduces the binding energy of water to native lectin molecules (from 4.3 to 4.1 J/g), but in the case of immobilized lectin in CDCl3 medium, the value of ΣgS increases from 5.2 to 7.4 J/g. That is, the weakly polar medium promotes to increase in the interaction of water with interfaces, which is manifested in a relative increase in the number of water clusters of smaller size (Fig. 4). It should be noted that weakly associated forms of water (signal 3) are also represented by several types of clusters that have a radius in the range R = 1–10 nm, and their size distribution changes significantly during immobilization of lectin on the surface of AM1. Probably, weakly associated types of water are formed both in cavities, between polymer chains of protein molecules, and on the surface of AM1, free of protein.","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":"19 8","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121008413","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}
Wettability is of pivotal importance in many areas of science and technology, ranging from the extractive industry to development of advanced functional materials and biomedicine problems. An increasing interest to wetting-related phenomena stimulates impetuous growth of research activity in this field. The presented review is aimed at the cumulative coverage of issues related to wettability and its investigation. It outlines basic concepts of wetting as a physical phenomenon, methods for its characterisation (with the emphasis on sessile drop techniques), and performances of contemporary instrumentation for wettability measurements. In the first section, physics of wettability is considered. The intermolecular interactions related to wetting are classified as dependent on their nature. Thus, discussion of interactions involving polar molecules covers permanent dipole - permanent dipole interactions and freely rotating permanent dipoles. Consideration of interactions resulting from the polarization of molecules includes interactions between ions and uncharged molecules, Debye interactions, and London dispersion interactions. Hydrogen bonds are discussed separately. The second section deals with the issues related to surface tension and its effect on shaping the surface of a liquid brought in contact with a solid body. The relationship between the surface tension and the contact angle as well as equations that quantify this relationship are discussed. The Young–Laplace equation governing the shape of the drop resting on the surface is analysed. The third section is devoted to the experimental characterization of surface wettability and the underlying theoretical analysis. Particular attention is paid to the method known as the Axisymmetric Drop Shape Analysis (ADSA). Principles of automated determination of relevant physical values from experimental data are briefly discussed. Basics of numerical techniques intended for analysing the digitized image of the drop and extracting information on surface tension and contact angle are outlined. In the fourth section, an overview of commercially available instrumentation for studying wettability and the contact angle measurements is presented. The prototype contact angle analyser designed and manufactured at the ISP NASU is introduced.
{"title":"Surface wetting and contact angle: basics and characterisation","authors":"G. Beketov, O. Shynkarenko","doi":"10.15407/hftp13.01.003","DOIUrl":"https://doi.org/10.15407/hftp13.01.003","url":null,"abstract":"Wettability is of pivotal importance in many areas of science and technology, ranging from the extractive industry to development of advanced functional materials and biomedicine problems. An increasing interest to wetting-related phenomena stimulates impetuous growth of research activity in this field. The presented review is aimed at the cumulative coverage of issues related to wettability and its investigation. It outlines basic concepts of wetting as a physical phenomenon, methods for its characterisation (with the emphasis on sessile drop techniques), and performances of contemporary instrumentation for wettability measurements. In the first section, physics of wettability is considered. The intermolecular interactions related to wetting are classified as dependent on their nature. Thus, discussion of interactions involving polar molecules covers permanent dipole - permanent dipole interactions and freely rotating permanent dipoles. Consideration of interactions resulting from the polarization of molecules includes interactions between ions and uncharged molecules, Debye interactions, and London dispersion interactions. Hydrogen bonds are discussed separately. The second section deals with the issues related to surface tension and its effect on shaping the surface of a liquid brought in contact with a solid body. The relationship between the surface tension and the contact angle as well as equations that quantify this relationship are discussed. The Young–Laplace equation governing the shape of the drop resting on the surface is analysed. The third section is devoted to the experimental characterization of surface wettability and the underlying theoretical analysis. Particular attention is paid to the method known as the Axisymmetric Drop Shape Analysis (ADSA). Principles of automated determination of relevant physical values from experimental data are briefly discussed. Basics of numerical techniques intended for analysing the digitized image of the drop and extracting information on surface tension and contact angle are outlined. In the fourth section, an overview of commercially available instrumentation for studying wettability and the contact angle measurements is presented. The prototype contact angle analyser designed and manufactured at the ISP NASU is introduced.","PeriodicalId":296392,"journal":{"name":"Himia, Fizika ta Tehnologia Poverhni","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116594299","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：