Nato Mirdzveli - Academia.edu (original) (raw)
Papers by Nato Mirdzveli
IOP Conference Series: Earth and Environmental Science
Mining waste can generate environment pollution including acid mine drainage (AMD). AMD is danger... more Mining waste can generate environment pollution including acid mine drainage (AMD). AMD is dangerous for its surroundings and can pollute surface and groundwater it is contacting with. Nanomaterials are advanced materials used in all fields of human activity and development. However, their production is still expensive and may pollute the environment due to the chemicals’ used and/or production of the energy needed for their synthesis. A smart solution could be use of mining waste and AMD to produce nanomaterials with properties similar to the properties of nanomaterials obtained from clean chemicals. Thus both waste will be valorised / decontaminated and useful and needed materials produced. This paper presents production of nanoparticles and nanomaterials from mining waste and AMD with emphasis on iron- and copper-based materials, as well as some applications of the obtained materials.
Apple Academic Press eBooks, Aug 11, 2023
Nucleation and Atmospheric Aerosols, 2022
Natural zeolite clinoptilolite has long been successfully used for water purification from heavy ... more Natural zeolite clinoptilolite has long been successfully used for water purification from heavy metals and ammonia, but phillipsite has a higher ion-exchange capacity and is more promising to use in this area. This paper considers the chemical composition, structure and properties of natural Georgian phillipsites and their modification by the ion exchange. X-ray diffraction patterns and infrared spectra confirm the preservation of the zeolite structure during ionexchange reactions carried out in solutions and in the solid state. The ion exchange capacity of phillipsites in relation to different ions is in the range of 1.5-3.3 meq/g, they have high selectivity towards ammonia, but the selectivity series depend on zeolite origin: K+>NH4+ for phillipsites from the Akhaltsikhe deposit, and NH4+ >K+ for phillipsites from the Shukhuti manifestation characterized by high content of potassium. The degree of substitution with heavy metal (Cu, Co, Pb) ions in the reactions in solutions is about 80%; by means of reactions in the solid state, phillipsites enriched with biocidal metals (Ag, Cu, Zn), exhibiting bacteriostatic activity against Escherichia coli, have been prepared. The results obtained allow us to conclude that Georgian natural phillipsites, in particular the samples from Shukhuti, can be successfully used for water purification as filtering materials with a surface protected from bacterial contamination.
Hìmìâ, fìzіka ta tehnologìâ poverhnì, Dec 30, 2022
The coronavirus pandemic has increased interest in antibacterial agents containing bioactive meta... more The coronavirus pandemic has increased interest in antibacterial agents containing bioactive metals, for which zeolites are promising carriers. On the other hand, zeolite adsorbents and ion exchangers containing bioactive metals and endowed with bactericidal properties are promising for water treatment and other environmental and medical applications. Silver-, copper-, and zinc-containing microporous materials have been prepared on the base of natural analcime, phillipsite and heulandite from Georgian manifestations using ion-exchange reactions between zeolite microcrystals and a salt of a corresponding transition metal in the solid phase followed by washing with distilled water. Synthesized in such way adsorbent-ion-exchangers are characterized by chemical composition based on the X-ray energy dispersion spectra, powder X-ray diffraction patterns, Fourier transform infra-red spectra and low-temperature adsorption-desorption isotherms of N 2. Obtained materials remain the zeolite crystal structure and contain 130-230 mg/g of silver, 65-72 mg/g of copper, and 58-86 mg/g of zinc, as compared with modified samples of synthetic type A zeolite containing up to 380 mg/g of silver, 150 mg/g of copper, and 150 mg/g of zinc. Prepared metal-containing materials show bacteriostatic activity against Gram negative bacterium Escherichia coli, Gram positive bacteria Staphylococcus aureus and Bacillus subtilis, fungal pathogenic yeast Candida albicans, and a fungus Aspergilus niger, and natural zeolites enriched with biometals exhibit a synergistic effect-their mixtures have a higher bacteriostatic activity. It is shown that mixtures of copper and zinc forms have a higher activity than the silvercontaining form, which is very important from a practical point of view for replacing expensive silver with cheaper copper and zinc. It has been found that the bacteriostatic activity of metal-containing zeolites is determined not only and not so much by the ions of bioactive metals released into the liquid medium, but an important role in inhibiting the growth of microorganisms plays a type of zeolite matrix. Despite the relatively low ion-exchange capacity, heulandite turned out to be a fairly effective matrix for bioactive metals.
Hìmìâ, fìzіka ta tehnologìâ poverhnì, Sep 30, 2017
Generally, the microporous structure of synthetic zeolite is affected by the nature of used react... more Generally, the microporous structure of synthetic zeolite is affected by the nature of used reactants and their pretreatments, as well as by composition of the reaction mixture. Our recent investigation of hydrothermal transformation of natural Georgian clinoptilolite demonstrated possibility of preparation of zeolites with high silicon content (mordenite-like materials) without organic template, directly from aged gels having suitable chemical composition and prepared by acid treatment of raw material. The aim of present work was preparation of zeolites with high aluminium content on the same basis without organic templates. The study tested possibility of synthesis of the LTA type zeolites in following steps: treatment of the natural clinoptilolite ((Na 3.3 K 1.15 Ca 0.75 Mg 0.25 [Me] 0.55)(Al 7.0 Si 29.3 O 72). 22.5H 2 O, where Me = Cu, Zn, Ba, etc.) in HCl water solution; gel preparation by suspension in NaOH solution; its hydrothermal crystallization to the sodalite structure (SOD) with Si/Al=1, and then re-crystallization of the sodalite into the NaA zeolite (LTA). Chemical elemental analyses confirm a good accordance with the UPAC SOD and LTA chemical formulas for prepared materials having nearly monocationic composition (Na-78 % SOD and 89 % LTA). In XRD patterns there are no additional peaks from zeolitic or other impurities, prepared materials have high crystallinity, their FTIR spectra are typical for SOD and LTA structures, developed zeolitic crystal microporous structure is confirmed by comparatively high averaged value of water adsorption capacity (0.08 cm 3 /g for SOD, and of 0.24 cm 3 /g for LTA at p/p S = 0.4). SEM images show uniform LTA micrometric crystallites (average diameter 4 μm) with fairly narrow distribution of sizes produced by lasting (> 10 h) low temperature crystallization, as well as nanoscale spherical zeolites (0.2 μm) and fibrous aggregates (0.08 μm) produced at low temperature, that can be used for preparation of composite and hierarchical structures for various catalytic and adsorptive applications.
InterConf, Mar 20, 2023
Adsorption properties and porous structure of acid treated natural heulandite-containing tuff fro... more Adsorption properties and porous structure of acid treated natural heulandite-containing tuff from the Rkoni plot of the Tedzami deposit (Eastern Georgia), a mixture of heulandite and chabazite from the Chankanay deposit (Kazakhstan, Almaty region), and clinoptilolitecontaining tuff from the Nor Kokhb deposit (Armenia, Noyemberian region), selected for the creation of new bactericidal zeolite filter materials for purification and desinfection of water from various sources, have been studied by water, benzene and nitrogen adsorption measurements. It was found that micropores of heulandite and clinoptilolite are in any case accessible to small water molecules; in Kazakhstani zeolite, they become accessible only after acid treatment, which also leads to a slight increase in surface hydrophobicity for all samples. Low-temperature nitrogen adsorption-desorption isotherms show acid-mediated sharp increase of adsorption in micropores and of the BET surface area, as well as changes in the mesoporous systems, leading to the prevalence of small pores with a diameter up to 4 nm in Georgian and Kazakhstani samples, and up to 3 nm in Armenian clinoptilolite, retaining larger pores in this sample, albeit reducing their volume.
InterConf, Aug 2, 2021
The purpose of present work was to obtain bactericidal materials using heulanditeclinoptilolite f... more The purpose of present work was to obtain bactericidal materials using heulanditeclinoptilolite from the Rkoni plot of the Tedzami deposit, Eastern Georgia, to study their properties and use them as a filler for the production of bactericidal paper. Silver-, copper-, and zinc-containing microporous materials have been prepared using ion-exchange reactions between preliminary acidtreated zeolite microcrystals and a salt of a corresponding bioactive metal in the solid phase followed by washing with distilled water. Synthesized in such way adsorbent-ion-exchangers are characterized SCIENTIFIC COLLECTION «INTERCONF» | № 67 341 by X-ray energy dispersion spectra, powder X-ray diffraction patterns, and Fourier transform infrared spectra. Obtained materials remain the zeolite crystal structure and contain over 130 mg/g of silver, 70 mg/g of copper, and 55 mg/g of zinc. Prepared materials show bacteriostatic activity towards gram-negative bacterium Escherichia coli, gram-positive bacteria Staphylococcus aureus and Bacillus subtilis, fungal pathogenic yeast Candida albicans, and a fungus Aspergilus niger. It was found that the mixtures of various forms exhibit a synergistic effect, and the silver form with additives of copper and zinc forms is most active against staphylococcus, and against other microorganisms, mixtures of copper and zinc forms are most effective.
Sustainable Extraction and Processing of Raw Materials
One of the commonly used methods for removing sulphates from mine waters is the precipitation. Th... more One of the commonly used methods for removing sulphates from mine waters is the precipitation. The classical approach for the treatment of acid mine drainage (AMD) rich in heavy metals and sulphates at about of 2000 mg/L is based on using Ba added in different forms - Ba(Cl)2, Ba(OH)2, BaCO3, BaS. In the present study, barite precipitation with the use of BaS was implemented in a laboratory installation in continuous mode. The scheme of the installation includes series-connected chemical reactors and settlers, which allows the sequential implementation of three processes - liming, barite precipitation and recarbonation. Real AMD containing high concentrations of sulphates and heavy metals has been effectively treated by the laboratory installation. The application of BaS effectively reduces the concentration of sulphates below 200 mg/L and the electrical conductivity of the treated waters is significantly reduced.
InterConf
Adsorption properties and porous structure of acid treated natural heulandite-containing tuff fro... more Adsorption properties and porous structure of acid treated natural heulandite-containing tuff from the Rkoni plot of the Tedzami deposit (Eastern Georgia), a mixture of heulandite and chabazite from the Chankanay deposit (Kazakhstan, Almaty region), and clinoptilolite-containing tuff from the Nor Kokhb deposit (Armenia, Noyemberian region), selected for the creation of new bactericidal zeolite filter materials for purification and desinfection of water from various sources, have been studied by water, benzene and nitrogen adsorption measurements. It was found that micropores of heulandite and clinoptilolite are in any case accessible to small water molecules; in Kazakhstani zeolite, they become accessible only after acid treatment, which also leads to a slight increase in surface hydrophobicity for all samples. Low-temperature nitrogen adsorption-desorption isotherms show acid-mediated sharp increase of adsorption in micropores and of the BET surface area, as well as changes in the ...
Minerals, Mar 4, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
InterConf, Jan 20, 2023
The article considers the processes leading to a change in the structure and properties as a resu... more The article considers the processes leading to a change in the structure and properties as a result of thermal treatment of natural zeolites from the Rkoni plot of the Tedzami deposit, Georgia, containing up to 80% of heulandite and 10% of chabazite, from the Chankanay deposit, Kazakhstan, containing up to 70% of heulandite-chabazite mixture, and from the Nor Kokhb deposit, Armenia, containing over 80% of clinoptilolite, selected for the creation of new bactericidal zeolite filter materials for purification and desinfection of water from various sources. The thermal stability of the samples is determined, the parameters of dehydration, amorphization and the effect of heat treatment on micro-and mesoporous systems of zeolites are established.
Hìmìâ, fìzіka ta tehnologìâ poverhnì, Dec 30, 2019
Zeolite adsorbents and ion exchangers reducing the concentrations of contaminants in aqueous medi... more Zeolite adsorbents and ion exchangers reducing the concentrations of contaminants in aqueous medium, containing bioactive metals and endowed with bactericidal properties are promising for application in environmental protection practice and medicine. Phillipsite has a high ion exchange capacity and can be used to produce such materials. Silver-, copper-, and zinc-containing micro-mesoporous zeolite materials have been prepared on the basis of natural phillipsite from the Shukhuti field, Western Georgia (Saqartvelo), using ionexchange reactions between grinded and washed by dilute hydrogen chloride solution zeolite and a salt of a corresponding transition metal in the solid phase followed by washing with distilled water. Synthesized in such way adsorbent-ion-exchangers are characterized by chemical analysis and sorption data (nitrogen adsorption-desorption isotherms at 77 K and water vapour sorption at room temperature), powder X-ray diffraction patterns, Fourier transform infra-red spectra, and scanning electron microscope images. Obtained materials keep the crystal structure and general sorption and ion-exchange properties of phillipsite, they contain up to 230 mg/g of silver, 66 mg/g of copper, and 86 mg/g of zinc, which is several times higher than the content of bioactive metals in the cationexchange forms of clinoptilolite and synthetic zeolites obtained by ion exchange in the liquid phase described in the literature. Prepared silver-, copper-, and zinc-containing phillipsites show bactericidal and bacteriostatic activity towards Escherichia coli regardless of whether the number of released ions of the bioactive metal reaches the minimum inhibitory concentration in solution. The procedure of dry ion-exchange synthesis leads to an increase in the dispersion of the material, but does not affect the developed mesoporous system of phillipsite and the total pore volume averaging 0.285 cm 3 /g. The compliance of proposed method for preparation of silver-, copper-, and zinccontaining forms of phillipsite with high environmental standards is confirmed by its low Sheldon's factor E in comparison with the similar green chemistry metrics of conventional methods of the ion exchange in solutions.
Composite consisting of natural zeolite and silver nanoparticles (AgNPs-zeolite) has been synthes... more Composite consisting of natural zeolite and silver nanoparticles (AgNPs-zeolite) has been synthesized by ion exchange followed by a thermal treatment. The prepared material is characterized by BET, EDX, TEM and XPS. The antibacterial activity of the synthesized material has been studied against Е. coli. Results on the influence of the material's doze and treatment time on the antimicrobial action of the composite are presented. The minimum inhibitory concentration is 10 mg AgNPs-zeolite/mL of culture medium containing E. coli (10 5 CFU/mL). Bactericidal activity has been observed after 300 minutes of treatment. The bactericidal action of the synthesized nanocomposite against E. coli is maintained after three repeated re-inoculations, and after the third inoculation it is 99.9%. Possible mechanism of the observed antimicrobial action is briefly discussed.
IOP Conference Series: Earth and Environmental Science
Mining waste can generate environment pollution including acid mine drainage (AMD). AMD is danger... more Mining waste can generate environment pollution including acid mine drainage (AMD). AMD is dangerous for its surroundings and can pollute surface and groundwater it is contacting with. Nanomaterials are advanced materials used in all fields of human activity and development. However, their production is still expensive and may pollute the environment due to the chemicals’ used and/or production of the energy needed for their synthesis. A smart solution could be use of mining waste and AMD to produce nanomaterials with properties similar to the properties of nanomaterials obtained from clean chemicals. Thus both waste will be valorised / decontaminated and useful and needed materials produced. This paper presents production of nanoparticles and nanomaterials from mining waste and AMD with emphasis on iron- and copper-based materials, as well as some applications of the obtained materials.
Apple Academic Press eBooks, Aug 11, 2023
Nucleation and Atmospheric Aerosols, 2022
Natural zeolite clinoptilolite has long been successfully used for water purification from heavy ... more Natural zeolite clinoptilolite has long been successfully used for water purification from heavy metals and ammonia, but phillipsite has a higher ion-exchange capacity and is more promising to use in this area. This paper considers the chemical composition, structure and properties of natural Georgian phillipsites and their modification by the ion exchange. X-ray diffraction patterns and infrared spectra confirm the preservation of the zeolite structure during ionexchange reactions carried out in solutions and in the solid state. The ion exchange capacity of phillipsites in relation to different ions is in the range of 1.5-3.3 meq/g, they have high selectivity towards ammonia, but the selectivity series depend on zeolite origin: K+>NH4+ for phillipsites from the Akhaltsikhe deposit, and NH4+ >K+ for phillipsites from the Shukhuti manifestation characterized by high content of potassium. The degree of substitution with heavy metal (Cu, Co, Pb) ions in the reactions in solutions is about 80%; by means of reactions in the solid state, phillipsites enriched with biocidal metals (Ag, Cu, Zn), exhibiting bacteriostatic activity against Escherichia coli, have been prepared. The results obtained allow us to conclude that Georgian natural phillipsites, in particular the samples from Shukhuti, can be successfully used for water purification as filtering materials with a surface protected from bacterial contamination.
Hìmìâ, fìzіka ta tehnologìâ poverhnì, Dec 30, 2022
The coronavirus pandemic has increased interest in antibacterial agents containing bioactive meta... more The coronavirus pandemic has increased interest in antibacterial agents containing bioactive metals, for which zeolites are promising carriers. On the other hand, zeolite adsorbents and ion exchangers containing bioactive metals and endowed with bactericidal properties are promising for water treatment and other environmental and medical applications. Silver-, copper-, and zinc-containing microporous materials have been prepared on the base of natural analcime, phillipsite and heulandite from Georgian manifestations using ion-exchange reactions between zeolite microcrystals and a salt of a corresponding transition metal in the solid phase followed by washing with distilled water. Synthesized in such way adsorbent-ion-exchangers are characterized by chemical composition based on the X-ray energy dispersion spectra, powder X-ray diffraction patterns, Fourier transform infra-red spectra and low-temperature adsorption-desorption isotherms of N 2. Obtained materials remain the zeolite crystal structure and contain 130-230 mg/g of silver, 65-72 mg/g of copper, and 58-86 mg/g of zinc, as compared with modified samples of synthetic type A zeolite containing up to 380 mg/g of silver, 150 mg/g of copper, and 150 mg/g of zinc. Prepared metal-containing materials show bacteriostatic activity against Gram negative bacterium Escherichia coli, Gram positive bacteria Staphylococcus aureus and Bacillus subtilis, fungal pathogenic yeast Candida albicans, and a fungus Aspergilus niger, and natural zeolites enriched with biometals exhibit a synergistic effect-their mixtures have a higher bacteriostatic activity. It is shown that mixtures of copper and zinc forms have a higher activity than the silvercontaining form, which is very important from a practical point of view for replacing expensive silver with cheaper copper and zinc. It has been found that the bacteriostatic activity of metal-containing zeolites is determined not only and not so much by the ions of bioactive metals released into the liquid medium, but an important role in inhibiting the growth of microorganisms plays a type of zeolite matrix. Despite the relatively low ion-exchange capacity, heulandite turned out to be a fairly effective matrix for bioactive metals.
Hìmìâ, fìzіka ta tehnologìâ poverhnì, Sep 30, 2017
Generally, the microporous structure of synthetic zeolite is affected by the nature of used react... more Generally, the microporous structure of synthetic zeolite is affected by the nature of used reactants and their pretreatments, as well as by composition of the reaction mixture. Our recent investigation of hydrothermal transformation of natural Georgian clinoptilolite demonstrated possibility of preparation of zeolites with high silicon content (mordenite-like materials) without organic template, directly from aged gels having suitable chemical composition and prepared by acid treatment of raw material. The aim of present work was preparation of zeolites with high aluminium content on the same basis without organic templates. The study tested possibility of synthesis of the LTA type zeolites in following steps: treatment of the natural clinoptilolite ((Na 3.3 K 1.15 Ca 0.75 Mg 0.25 [Me] 0.55)(Al 7.0 Si 29.3 O 72). 22.5H 2 O, where Me = Cu, Zn, Ba, etc.) in HCl water solution; gel preparation by suspension in NaOH solution; its hydrothermal crystallization to the sodalite structure (SOD) with Si/Al=1, and then re-crystallization of the sodalite into the NaA zeolite (LTA). Chemical elemental analyses confirm a good accordance with the UPAC SOD and LTA chemical formulas for prepared materials having nearly monocationic composition (Na-78 % SOD and 89 % LTA). In XRD patterns there are no additional peaks from zeolitic or other impurities, prepared materials have high crystallinity, their FTIR spectra are typical for SOD and LTA structures, developed zeolitic crystal microporous structure is confirmed by comparatively high averaged value of water adsorption capacity (0.08 cm 3 /g for SOD, and of 0.24 cm 3 /g for LTA at p/p S = 0.4). SEM images show uniform LTA micrometric crystallites (average diameter 4 μm) with fairly narrow distribution of sizes produced by lasting (> 10 h) low temperature crystallization, as well as nanoscale spherical zeolites (0.2 μm) and fibrous aggregates (0.08 μm) produced at low temperature, that can be used for preparation of composite and hierarchical structures for various catalytic and adsorptive applications.
InterConf, Mar 20, 2023
Adsorption properties and porous structure of acid treated natural heulandite-containing tuff fro... more Adsorption properties and porous structure of acid treated natural heulandite-containing tuff from the Rkoni plot of the Tedzami deposit (Eastern Georgia), a mixture of heulandite and chabazite from the Chankanay deposit (Kazakhstan, Almaty region), and clinoptilolitecontaining tuff from the Nor Kokhb deposit (Armenia, Noyemberian region), selected for the creation of new bactericidal zeolite filter materials for purification and desinfection of water from various sources, have been studied by water, benzene and nitrogen adsorption measurements. It was found that micropores of heulandite and clinoptilolite are in any case accessible to small water molecules; in Kazakhstani zeolite, they become accessible only after acid treatment, which also leads to a slight increase in surface hydrophobicity for all samples. Low-temperature nitrogen adsorption-desorption isotherms show acid-mediated sharp increase of adsorption in micropores and of the BET surface area, as well as changes in the mesoporous systems, leading to the prevalence of small pores with a diameter up to 4 nm in Georgian and Kazakhstani samples, and up to 3 nm in Armenian clinoptilolite, retaining larger pores in this sample, albeit reducing their volume.
InterConf, Aug 2, 2021
The purpose of present work was to obtain bactericidal materials using heulanditeclinoptilolite f... more The purpose of present work was to obtain bactericidal materials using heulanditeclinoptilolite from the Rkoni plot of the Tedzami deposit, Eastern Georgia, to study their properties and use them as a filler for the production of bactericidal paper. Silver-, copper-, and zinc-containing microporous materials have been prepared using ion-exchange reactions between preliminary acidtreated zeolite microcrystals and a salt of a corresponding bioactive metal in the solid phase followed by washing with distilled water. Synthesized in such way adsorbent-ion-exchangers are characterized SCIENTIFIC COLLECTION «INTERCONF» | № 67 341 by X-ray energy dispersion spectra, powder X-ray diffraction patterns, and Fourier transform infrared spectra. Obtained materials remain the zeolite crystal structure and contain over 130 mg/g of silver, 70 mg/g of copper, and 55 mg/g of zinc. Prepared materials show bacteriostatic activity towards gram-negative bacterium Escherichia coli, gram-positive bacteria Staphylococcus aureus and Bacillus subtilis, fungal pathogenic yeast Candida albicans, and a fungus Aspergilus niger. It was found that the mixtures of various forms exhibit a synergistic effect, and the silver form with additives of copper and zinc forms is most active against staphylococcus, and against other microorganisms, mixtures of copper and zinc forms are most effective.
Sustainable Extraction and Processing of Raw Materials
One of the commonly used methods for removing sulphates from mine waters is the precipitation. Th... more One of the commonly used methods for removing sulphates from mine waters is the precipitation. The classical approach for the treatment of acid mine drainage (AMD) rich in heavy metals and sulphates at about of 2000 mg/L is based on using Ba added in different forms - Ba(Cl)2, Ba(OH)2, BaCO3, BaS. In the present study, barite precipitation with the use of BaS was implemented in a laboratory installation in continuous mode. The scheme of the installation includes series-connected chemical reactors and settlers, which allows the sequential implementation of three processes - liming, barite precipitation and recarbonation. Real AMD containing high concentrations of sulphates and heavy metals has been effectively treated by the laboratory installation. The application of BaS effectively reduces the concentration of sulphates below 200 mg/L and the electrical conductivity of the treated waters is significantly reduced.
InterConf
Adsorption properties and porous structure of acid treated natural heulandite-containing tuff fro... more Adsorption properties and porous structure of acid treated natural heulandite-containing tuff from the Rkoni plot of the Tedzami deposit (Eastern Georgia), a mixture of heulandite and chabazite from the Chankanay deposit (Kazakhstan, Almaty region), and clinoptilolite-containing tuff from the Nor Kokhb deposit (Armenia, Noyemberian region), selected for the creation of new bactericidal zeolite filter materials for purification and desinfection of water from various sources, have been studied by water, benzene and nitrogen adsorption measurements. It was found that micropores of heulandite and clinoptilolite are in any case accessible to small water molecules; in Kazakhstani zeolite, they become accessible only after acid treatment, which also leads to a slight increase in surface hydrophobicity for all samples. Low-temperature nitrogen adsorption-desorption isotherms show acid-mediated sharp increase of adsorption in micropores and of the BET surface area, as well as changes in the ...
Minerals, Mar 4, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
InterConf, Jan 20, 2023
The article considers the processes leading to a change in the structure and properties as a resu... more The article considers the processes leading to a change in the structure and properties as a result of thermal treatment of natural zeolites from the Rkoni plot of the Tedzami deposit, Georgia, containing up to 80% of heulandite and 10% of chabazite, from the Chankanay deposit, Kazakhstan, containing up to 70% of heulandite-chabazite mixture, and from the Nor Kokhb deposit, Armenia, containing over 80% of clinoptilolite, selected for the creation of new bactericidal zeolite filter materials for purification and desinfection of water from various sources. The thermal stability of the samples is determined, the parameters of dehydration, amorphization and the effect of heat treatment on micro-and mesoporous systems of zeolites are established.
Hìmìâ, fìzіka ta tehnologìâ poverhnì, Dec 30, 2019
Zeolite adsorbents and ion exchangers reducing the concentrations of contaminants in aqueous medi... more Zeolite adsorbents and ion exchangers reducing the concentrations of contaminants in aqueous medium, containing bioactive metals and endowed with bactericidal properties are promising for application in environmental protection practice and medicine. Phillipsite has a high ion exchange capacity and can be used to produce such materials. Silver-, copper-, and zinc-containing micro-mesoporous zeolite materials have been prepared on the basis of natural phillipsite from the Shukhuti field, Western Georgia (Saqartvelo), using ionexchange reactions between grinded and washed by dilute hydrogen chloride solution zeolite and a salt of a corresponding transition metal in the solid phase followed by washing with distilled water. Synthesized in such way adsorbent-ion-exchangers are characterized by chemical analysis and sorption data (nitrogen adsorption-desorption isotherms at 77 K and water vapour sorption at room temperature), powder X-ray diffraction patterns, Fourier transform infra-red spectra, and scanning electron microscope images. Obtained materials keep the crystal structure and general sorption and ion-exchange properties of phillipsite, they contain up to 230 mg/g of silver, 66 mg/g of copper, and 86 mg/g of zinc, which is several times higher than the content of bioactive metals in the cationexchange forms of clinoptilolite and synthetic zeolites obtained by ion exchange in the liquid phase described in the literature. Prepared silver-, copper-, and zinc-containing phillipsites show bactericidal and bacteriostatic activity towards Escherichia coli regardless of whether the number of released ions of the bioactive metal reaches the minimum inhibitory concentration in solution. The procedure of dry ion-exchange synthesis leads to an increase in the dispersion of the material, but does not affect the developed mesoporous system of phillipsite and the total pore volume averaging 0.285 cm 3 /g. The compliance of proposed method for preparation of silver-, copper-, and zinccontaining forms of phillipsite with high environmental standards is confirmed by its low Sheldon's factor E in comparison with the similar green chemistry metrics of conventional methods of the ion exchange in solutions.
Composite consisting of natural zeolite and silver nanoparticles (AgNPs-zeolite) has been synthes... more Composite consisting of natural zeolite and silver nanoparticles (AgNPs-zeolite) has been synthesized by ion exchange followed by a thermal treatment. The prepared material is characterized by BET, EDX, TEM and XPS. The antibacterial activity of the synthesized material has been studied against Е. coli. Results on the influence of the material's doze and treatment time on the antimicrobial action of the composite are presented. The minimum inhibitory concentration is 10 mg AgNPs-zeolite/mL of culture medium containing E. coli (10 5 CFU/mL). Bactericidal activity has been observed after 300 minutes of treatment. The bactericidal action of the synthesized nanocomposite against E. coli is maintained after three repeated re-inoculations, and after the third inoculation it is 99.9%. Possible mechanism of the observed antimicrobial action is briefly discussed.