Polyurethane (PU) solved in dimethylformamide (DMF) was electrospun under one set of conditions b... more Polyurethane (PU) solved in dimethylformamide (DMF) was electrospun under one set of conditions by using two different supporting textiles. The mechanical properties of nanofiber mats were measured by the Sentmanat extensional rheometer and the pore size distribution was calculated by a newly proposed digital image analysis methodology applied on nanoscale SEM images taking macroscopic features of the nonwovens into account. It has been found that supporting textiles have very high effect on mechanical properties of nanofiber mats (even if their fiber diameter distributions are similar), which can be explained by different porosity of the prepared samples
Mechanisms of capture of dust particles, two-and three dimensional modelling of properties of fil... more Mechanisms of capture of dust particles, two-and three dimensional modelling of properties of filtration materials and effect of selected variables on electrospinning of polyurethane (PU) solutions are discussed with the aim to prepare a nanofibre structure capable of capturing ultrafine particles. The two-dimensional modelling is used to gain an idea of the effect of mass per square area, thickness of nanofibre layers and nanofibre diameter on filtration efficiency of ultrafine particles. Values of filtration efficiency calculated at the three-dimensional modelling of the filtration process are compared with experimental measurements for sets of filtered particles 100 nm in diameter or bigger. The most important characteristics affecting quality of nanofibre materials are nanofibre diameter, porosity and homogeneity of nanofibre layers. The method making possible to achieve the required diameter of the nanofibres is demonstrated on the influence of relative humidity and solvent type on the fibre-forming process taking place in an electrostatic field. The effect of homogeneity of the nanofibre deposition on the collecting substrate is assessed employing images from scanning electron microscopy (SEM) and tests of filtering abilities of the nanofibre layers. Also, some measurements obtained when nanofibres were used in filtration of air, liquids and dispersions of carbon nanotubes in a liquid are presented.
Two different types of nanofibers were prepared by electrospinning, namely poly-(vinylidene fluor... more Two different types of nanofibers were prepared by electrospinning, namely poly-(vinylidene fluoride) PVDF and PVDF/TiO2. The prepared nanofibers have piezoelectric properties, which are characterized by the content of ß-phase. Another way to improve the piezoelectric properties is to use TiO2 nanoparticles, which increases the piezoelectric effect. Piezoelectric effect is strongly connected with capacitive properties which was investigated in this work. Capacitive sensor with a sandwich structure consisting of EVA foam as a cover, conductive copper fabric and nanofibers was prepared. The sensor is light-weight, flexible with the possibility of using for wearable electronics. We can therefore determine the maximum pressure at individual points of the foot, the course of its values, the method of pressure distribution throughout the foot. We can find use not only in research on walking, running and postures, but also, provide information on the magnitude of the applied force over time. The force converted to the selected sensor area is then pressure information.
In this work, novel 3D filtration model for nanofiber based filters has been proposed and tested.... more In this work, novel 3D filtration model for nanofiber based filters has been proposed and tested. For the model validation purposes, filtration efficiency characteristics of two different polyurethane nanofiber based structures (prepared by the electrospinning process) were determined experimentally in the ultrafine particle size range (20-400 nm). It has been found that the proposed model is able to reasonably predict the measured filtration efficiency curves for both tested samples.
For an effective modification of polyalkenes leading to the formation of block and/or graft copol... more For an effective modification of polyalkenes leading to the formation of block and/or graft copolymers, the presence of co-initiating water is absolutely necessary. We have compared two procedures used in the co-initiation of cationic reactions on polymers. Gradually supplied air moisture raises the efficiency of modification of isotactic polypropylene with poly(oxyethylene) several times, compared with a single addition of co-initiating water.
Polyurethane (PU) and PU/multiwalled carbon nanotube (MWCNT) nanocomposite nanofibers, both with ... more Polyurethane (PU) and PU/multiwalled carbon nanotube (MWCNT) nanocomposite nanofibers, both with diameters of 350 nm, were prepared by an electrospinning process from PU dimethylformamide solutions. The appearance of nanowebs in PU/MWCNT nanofiber structures containing PU fibers with diameters of 20-40 nm was observed. The existence of these structures could have been based on the occurrence of strong secondary electric fields, which were created between individual conducting MWCNTs (distributed in the PU/MWCNT nanocomposites), which started to behave as the local moving nanoelectrodes promoting the creation of additional very fine nanowebs during the electrospinning processes. To our knowledge, this is the first report describing nanowebs from synthetic polymers prepared by an electrospinning process.
Polyvinyl acetate (PVAc) nanofibers were prepared by technology of electrospinning with help of m... more Polyvinyl acetate (PVAc) nanofibers were prepared by technology of electrospinning with help of multi-jets electrospinning machine from acetic acid/water solvent system. The stability of the process was tested in a broad concentration region from 5 to 40 wt. % of PVAc. The main attention was carried out to study the effect of polyvinyl acetate solution concentration/viscosity onto mean diameter of prepared nanofibers. It was found that increased solution viscosity leads to increase of fibers diameters from appox. 60 nm at viscosity ~ 0.04 Pa.s to appox. 1000 nm at viscosity ~ 6-7 Pa.s. The PVAc nanofibres can be considered as a potential precursor for preparation of inorganic fibrous nanoparticles. Their dimensions can be effectively controlled by PVAc nanofibers diameter by easy diameter-concentration/viscosity optimalization.
Environmental Science: Water Research & Technology
Polyurethane-based nanofibrous structures can be used as adsorbents for arsenic in water. Their a... more Polyurethane-based nanofibrous structures can be used as adsorbents for arsenic in water. Their adsorption capacity can be significantly increased by doping the structure with ferrous sulphate.
2020 IEEE 15th International Conference on Nano/Micro Engineered and Molecular System (NEMS)
Two different types of nanofibers were prepared by electrospinning, namely poly-(vinylidene fluor... more Two different types of nanofibers were prepared by electrospinning, namely poly-(vinylidene fluoride) PVDF and PVDF/TiO2. The prepared nanofibers have piezoelectric properties, which are characterized by the content of ß-phase. Another way to improve the piezoelectric properties is to use TiO2 nanoparticles, which increases the piezoelectric effect. Piezoelectric effect is strongly connected with capacitive properties which was investigated in this work. Capacitive sensor with a sandwich structure consisting of EVA foam as a cover, conductive copper fabric and nanofibers was prepared. The sensor is light-weight, flexible with the possibility of using for wearable electronics. We can therefore determine the maximum pressure at individual points of the foot, the course of its values, the method of pressure distribution throughout the foot. We can find use not only in research on walking, running and postures, but also, provide information on the magnitude of the applied force over time. The force converted to the selected sensor area is then pressure information.
Journal of Environmental Health Science and Engineering, 2021
This research paper focuses on removing of arsenic from contaminated water via a nanofibrous poly... more This research paper focuses on removing of arsenic from contaminated water via a nanofibrous polymeric microfiltration membrane, applied in prospective combination with an inorganic sorbent based on iron oxide hydroxide FeO(OH). Nanofibrous materials were prepared by electrospinning from polyurethane selected by an adsorption test. The chemical composition (FTIR), morphology (SEM, porometry) and hydrophilicity (contact angle) of the prepared nanostructured material were characterized. The process of eliminating arsenic from the contaminated water was monitored by atomic absorption spectroscopy (AAS). The adsorption efficiency of the nanofibrous material and the combination with FeO(OH) was determined, the level of arsenic anchorage on the adsorption filter was assessed by a rinsing test and the selectivity of adsorption in arsenic contaminated mineral water was examined. It was confirmed that the hydrophilic aromatic polyurethane of ester type PU918 is capable of capturing arsenic by complexation on nitrogen in its polymer chains. The maximum As removal efficiency was around 62 %. Arsenic was tightly anchored to the polymeric adsorbent. The adsorption process was sufficiently selective. Furthermore, it was found that the addition of even a small amount of FeO(OH) (0.5 g) to the nanofiber filter would increase the efficiency of As removal by 30 %. The presented results showed that an adsorption filter based on a polyurethane nanostructured membrane added with an inorganic adsorbent FeO(OH) is a suitable way for the elimination of arsenic from water. However, it is necessary to ensure perfect contact between the surface of the nanostructure and the filtered medium.
The aim of this study was to estimate the influence of purification and treatment with textile fi... more The aim of this study was to estimate the influence of purification and treatment with textile finishing agent procedures on structural, mechanical, and water barrier properties of bacterial cellulose (BC) in order to predict the end-use properties. Kombucha fungus generated by Komagataeibacter xylinus species, formerly known as Gluconacetobacter xylinus, was used to produce the BC material. The BC was purified with 0.5% sodium hydroxide (NaOH) solution and treated with 5%, 10%, and 20% concentration of N, N-dimethylol 4,5-dihydroxy-ethylene urea (DMDHEU). By Fourier transform spectroscopy (FTIR) and X-ray diffractometer (XRD) was estimated, that the purification with a weak alkali solution was effective to remove amorphous matter of the BC material. Scanning electron microscope (SEM) images demonstrated the BC structure, similar to a non-woven textile fabric with clearly visible three-dimensional networks of fine cellulose fibers. After the purification process, the BC material ten...
Unique properties of electrospun nanofibrous materials could be utilized in various environmental... more Unique properties of electrospun nanofibrous materials could be utilized in various environmental technologies, e.g. bacteria removal from water. Recent studies show various removal efficiencies of bacteria and particulated matter by nanofibrous filters. Our article presents results from filtration tests through polyurethane nanofibrous material on short-term scale with artificial wastewater and also results from tests with real wastewater. We determined E. coli abundances in artificial and real wastewaters and the amount of the other hygienically important bacteria in real wastewater samples only. The results show possibility of long-term full-scale application of those materials, however some material modifications are needed to be accomplished.
The high aspect ratio of layered silicate nanoparticles is very convenient to modify the properti... more The high aspect ratio of layered silicate nanoparticles is very convenient to modify the properties of the polymer, but the hydrophilic nature of silicate surfaces impedes their homogeneous dispersion in the organic polymer phase. The hydrophilic clay minerals are commonly treated with ammonium cations with long alkyl chains to improve the compatibility between the silicate layers and the polymer matrix. In this study, clay mineral vermiculite (V) was used as a clay nanofiller to the polyethylene (PE) and the functional and mechanical properties of PE/V nanocomposite plates were characterized. Vermiculite has been modified to the role of nanofiller with organic dodecylamine (DA) compounds in various concentrations. Exfoliation of modified vermiculite nanofiller in PE was studied on the nanocomposite plates using X-ray diffraction analysis. The quality of nanofiller distribution in polymer matrix was observed using light microscopy. Changes in mechanical properties of the PE/VDA nano...
A filtration model taking particle-fiber as well as particle-particle interactions into account w... more A filtration model taking particle-fiber as well as particle-particle interactions into account was suggested and applied on a 3D simulation model of the nanofiber based filter, which was based on its SEM image. A theoretical study was done to evaluate the filtration efficiency as a function of number of particles, way of distributing the particles and the penetration profile through the filter. It was clearly shown that the cake formation has a significant effect on the filtration efficiency. Additionally, a visual representation of the cake formation was generated according the suggested model to get a better understanding of the cake morphology. Key-Words: Nanofiber Based Filter, Cake Formation, 3D Filtration Modeling, Electrospinning
Multi-wall carbon nanotube networks were prepared by process of filtration of CNT aqueous dispers... more Multi-wall carbon nanotube networks were prepared by process of filtration of CNT aqueous dispersions. CNT dispersions were prepared with help of surfactant system (Sodium dodecyl sulfate with amylalcohol) by ultrasonication. Three types of MWCNT tubes were used. The first were pure CNT material delivered by supplier. The other were chemically treated in aim to prepare CNT oxidised forms (1. acid solution of KMnO 4, 2. mixture of acids H 2SO 4 + HNO 3). It was found that chemical modification significantly changes properties of prepared carbon nanotube networks (“Buckypaper”). There were observed differences in porous structure between all of the forms analysed by SEM microscopy. Further, apparent density of prepared “Buckypapers” changes in respect of used CNT material leading to different porosity of Buckypapers. Electrical resistance is also affected by process of MWCNT oxidation together with its temperature dependence. Effect of compressive strain on electric resistance of mult...
The ever-increasing population has aroused demand for contraceptive chemicals which pollute the w... more The ever-increasing population has aroused demand for contraceptive chemicals which pollute the water reservoirs through industrial effluents. This has caused a severe threat to marine life and high concern about the availability of fresh drinkable water for people all over the world. Not only this, the unwanted intake of these water containing hormones leads to fertility disorder, rapid femininity, loss in male sperm count, high chances of breast, and ovarian cancer. Therefore, in this study, a one-step high-pressure liquid chromatography (HPLC) technique was devised for simultaneous detection and quantification of various estrogenic hormones from wastewater. Four representative hormones Estrone (E1), β-Estradiol (E2), Estriol (E3), and 17α-Ethinylestradiol (EE2) were used. To address the solubility of these hormones, a study was conducted in three solvents systems viz. ethanol, ethanol: water (20:80), and water, respectively. Similarly, calibration curves were made for these three solvent systems with regression coefficients ≥0.99. Interestingly, it was found that water can be used as a solvent for the estrogenic hormones at a detection limit as low as 5 µg/L, which makes this study quite significant.
Jaroslav Lev , Marek HOLBA , Libor KALHOTKA , Monika SZOSTKOVÁ , Dušan KIMMER d a ASIO spol. s r.... more Jaroslav Lev , Marek HOLBA , Libor KALHOTKA , Monika SZOSTKOVÁ , Dušan KIMMER d a ASIO spol. s r.o.,Tuřanka 1, 627 00 Brno, Czech Republic, EU, [email protected], b Institute of Botany, Academy of Science of the Czech Republic, v.v.i., Lidická 25/27, 657 20 Brno, Czech Republic EU, [email protected] b c Faculty of Agronomy of Mendelu in Brno, Zemědělská 1, 613 00 Brno, Czech Republic, EU, [email protected], [email protected]
Selected procedures permitting to prepare homogeneous nanofibre structures of the desired morphol... more Selected procedures permitting to prepare homogeneous nanofibre structures of the desired morphology by employing a suitable combination of variables during the electrospinning process are presented. A comparison (at the same pressure drop) was made of filtration capabilities of planar polyurethane nanostructures formed exclusively by nanofibres and space nanostructures having bead spacers or structures formed by a combination of microand nanofibres, through which ultrafine particles of ammonium sulphate 20 – 400 nm in size were filtered. The structures studied were described using a new digital image analysis technique based on black and white images obtained by scanning electron microscopy. More voluminous structures modified with distance microspheres and having a greater thickness and mass per square area of the material, i.e. structures possessing better mechanical properties, demanded so much in nanostructures, enable preparation of filters having approximately the same free v...
Polyurethane (PU) solved in dimethylformamide (DMF) was electrospun under one set of conditions b... more Polyurethane (PU) solved in dimethylformamide (DMF) was electrospun under one set of conditions by using two different supporting textiles. The mechanical properties of nanofiber mats were measured by the Sentmanat extensional rheometer and the pore size distribution was calculated by a newly proposed digital image analysis methodology applied on nanoscale SEM images taking macroscopic features of the nonwovens into account. It has been found that supporting textiles have very high effect on mechanical properties of nanofiber mats (even if their fiber diameter distributions are similar), which can be explained by different porosity of the prepared samples
Mechanisms of capture of dust particles, two-and three dimensional modelling of properties of fil... more Mechanisms of capture of dust particles, two-and three dimensional modelling of properties of filtration materials and effect of selected variables on electrospinning of polyurethane (PU) solutions are discussed with the aim to prepare a nanofibre structure capable of capturing ultrafine particles. The two-dimensional modelling is used to gain an idea of the effect of mass per square area, thickness of nanofibre layers and nanofibre diameter on filtration efficiency of ultrafine particles. Values of filtration efficiency calculated at the three-dimensional modelling of the filtration process are compared with experimental measurements for sets of filtered particles 100 nm in diameter or bigger. The most important characteristics affecting quality of nanofibre materials are nanofibre diameter, porosity and homogeneity of nanofibre layers. The method making possible to achieve the required diameter of the nanofibres is demonstrated on the influence of relative humidity and solvent type on the fibre-forming process taking place in an electrostatic field. The effect of homogeneity of the nanofibre deposition on the collecting substrate is assessed employing images from scanning electron microscopy (SEM) and tests of filtering abilities of the nanofibre layers. Also, some measurements obtained when nanofibres were used in filtration of air, liquids and dispersions of carbon nanotubes in a liquid are presented.
Two different types of nanofibers were prepared by electrospinning, namely poly-(vinylidene fluor... more Two different types of nanofibers were prepared by electrospinning, namely poly-(vinylidene fluoride) PVDF and PVDF/TiO2. The prepared nanofibers have piezoelectric properties, which are characterized by the content of ß-phase. Another way to improve the piezoelectric properties is to use TiO2 nanoparticles, which increases the piezoelectric effect. Piezoelectric effect is strongly connected with capacitive properties which was investigated in this work. Capacitive sensor with a sandwich structure consisting of EVA foam as a cover, conductive copper fabric and nanofibers was prepared. The sensor is light-weight, flexible with the possibility of using for wearable electronics. We can therefore determine the maximum pressure at individual points of the foot, the course of its values, the method of pressure distribution throughout the foot. We can find use not only in research on walking, running and postures, but also, provide information on the magnitude of the applied force over time. The force converted to the selected sensor area is then pressure information.
In this work, novel 3D filtration model for nanofiber based filters has been proposed and tested.... more In this work, novel 3D filtration model for nanofiber based filters has been proposed and tested. For the model validation purposes, filtration efficiency characteristics of two different polyurethane nanofiber based structures (prepared by the electrospinning process) were determined experimentally in the ultrafine particle size range (20-400 nm). It has been found that the proposed model is able to reasonably predict the measured filtration efficiency curves for both tested samples.
For an effective modification of polyalkenes leading to the formation of block and/or graft copol... more For an effective modification of polyalkenes leading to the formation of block and/or graft copolymers, the presence of co-initiating water is absolutely necessary. We have compared two procedures used in the co-initiation of cationic reactions on polymers. Gradually supplied air moisture raises the efficiency of modification of isotactic polypropylene with poly(oxyethylene) several times, compared with a single addition of co-initiating water.
Polyurethane (PU) and PU/multiwalled carbon nanotube (MWCNT) nanocomposite nanofibers, both with ... more Polyurethane (PU) and PU/multiwalled carbon nanotube (MWCNT) nanocomposite nanofibers, both with diameters of 350 nm, were prepared by an electrospinning process from PU dimethylformamide solutions. The appearance of nanowebs in PU/MWCNT nanofiber structures containing PU fibers with diameters of 20-40 nm was observed. The existence of these structures could have been based on the occurrence of strong secondary electric fields, which were created between individual conducting MWCNTs (distributed in the PU/MWCNT nanocomposites), which started to behave as the local moving nanoelectrodes promoting the creation of additional very fine nanowebs during the electrospinning processes. To our knowledge, this is the first report describing nanowebs from synthetic polymers prepared by an electrospinning process.
Polyvinyl acetate (PVAc) nanofibers were prepared by technology of electrospinning with help of m... more Polyvinyl acetate (PVAc) nanofibers were prepared by technology of electrospinning with help of multi-jets electrospinning machine from acetic acid/water solvent system. The stability of the process was tested in a broad concentration region from 5 to 40 wt. % of PVAc. The main attention was carried out to study the effect of polyvinyl acetate solution concentration/viscosity onto mean diameter of prepared nanofibers. It was found that increased solution viscosity leads to increase of fibers diameters from appox. 60 nm at viscosity ~ 0.04 Pa.s to appox. 1000 nm at viscosity ~ 6-7 Pa.s. The PVAc nanofibres can be considered as a potential precursor for preparation of inorganic fibrous nanoparticles. Their dimensions can be effectively controlled by PVAc nanofibers diameter by easy diameter-concentration/viscosity optimalization.
Environmental Science: Water Research & Technology
Polyurethane-based nanofibrous structures can be used as adsorbents for arsenic in water. Their a... more Polyurethane-based nanofibrous structures can be used as adsorbents for arsenic in water. Their adsorption capacity can be significantly increased by doping the structure with ferrous sulphate.
2020 IEEE 15th International Conference on Nano/Micro Engineered and Molecular System (NEMS)
Two different types of nanofibers were prepared by electrospinning, namely poly-(vinylidene fluor... more Two different types of nanofibers were prepared by electrospinning, namely poly-(vinylidene fluoride) PVDF and PVDF/TiO2. The prepared nanofibers have piezoelectric properties, which are characterized by the content of ß-phase. Another way to improve the piezoelectric properties is to use TiO2 nanoparticles, which increases the piezoelectric effect. Piezoelectric effect is strongly connected with capacitive properties which was investigated in this work. Capacitive sensor with a sandwich structure consisting of EVA foam as a cover, conductive copper fabric and nanofibers was prepared. The sensor is light-weight, flexible with the possibility of using for wearable electronics. We can therefore determine the maximum pressure at individual points of the foot, the course of its values, the method of pressure distribution throughout the foot. We can find use not only in research on walking, running and postures, but also, provide information on the magnitude of the applied force over time. The force converted to the selected sensor area is then pressure information.
Journal of Environmental Health Science and Engineering, 2021
This research paper focuses on removing of arsenic from contaminated water via a nanofibrous poly... more This research paper focuses on removing of arsenic from contaminated water via a nanofibrous polymeric microfiltration membrane, applied in prospective combination with an inorganic sorbent based on iron oxide hydroxide FeO(OH). Nanofibrous materials were prepared by electrospinning from polyurethane selected by an adsorption test. The chemical composition (FTIR), morphology (SEM, porometry) and hydrophilicity (contact angle) of the prepared nanostructured material were characterized. The process of eliminating arsenic from the contaminated water was monitored by atomic absorption spectroscopy (AAS). The adsorption efficiency of the nanofibrous material and the combination with FeO(OH) was determined, the level of arsenic anchorage on the adsorption filter was assessed by a rinsing test and the selectivity of adsorption in arsenic contaminated mineral water was examined. It was confirmed that the hydrophilic aromatic polyurethane of ester type PU918 is capable of capturing arsenic by complexation on nitrogen in its polymer chains. The maximum As removal efficiency was around 62 %. Arsenic was tightly anchored to the polymeric adsorbent. The adsorption process was sufficiently selective. Furthermore, it was found that the addition of even a small amount of FeO(OH) (0.5 g) to the nanofiber filter would increase the efficiency of As removal by 30 %. The presented results showed that an adsorption filter based on a polyurethane nanostructured membrane added with an inorganic adsorbent FeO(OH) is a suitable way for the elimination of arsenic from water. However, it is necessary to ensure perfect contact between the surface of the nanostructure and the filtered medium.
The aim of this study was to estimate the influence of purification and treatment with textile fi... more The aim of this study was to estimate the influence of purification and treatment with textile finishing agent procedures on structural, mechanical, and water barrier properties of bacterial cellulose (BC) in order to predict the end-use properties. Kombucha fungus generated by Komagataeibacter xylinus species, formerly known as Gluconacetobacter xylinus, was used to produce the BC material. The BC was purified with 0.5% sodium hydroxide (NaOH) solution and treated with 5%, 10%, and 20% concentration of N, N-dimethylol 4,5-dihydroxy-ethylene urea (DMDHEU). By Fourier transform spectroscopy (FTIR) and X-ray diffractometer (XRD) was estimated, that the purification with a weak alkali solution was effective to remove amorphous matter of the BC material. Scanning electron microscope (SEM) images demonstrated the BC structure, similar to a non-woven textile fabric with clearly visible three-dimensional networks of fine cellulose fibers. After the purification process, the BC material ten...
Unique properties of electrospun nanofibrous materials could be utilized in various environmental... more Unique properties of electrospun nanofibrous materials could be utilized in various environmental technologies, e.g. bacteria removal from water. Recent studies show various removal efficiencies of bacteria and particulated matter by nanofibrous filters. Our article presents results from filtration tests through polyurethane nanofibrous material on short-term scale with artificial wastewater and also results from tests with real wastewater. We determined E. coli abundances in artificial and real wastewaters and the amount of the other hygienically important bacteria in real wastewater samples only. The results show possibility of long-term full-scale application of those materials, however some material modifications are needed to be accomplished.
The high aspect ratio of layered silicate nanoparticles is very convenient to modify the properti... more The high aspect ratio of layered silicate nanoparticles is very convenient to modify the properties of the polymer, but the hydrophilic nature of silicate surfaces impedes their homogeneous dispersion in the organic polymer phase. The hydrophilic clay minerals are commonly treated with ammonium cations with long alkyl chains to improve the compatibility between the silicate layers and the polymer matrix. In this study, clay mineral vermiculite (V) was used as a clay nanofiller to the polyethylene (PE) and the functional and mechanical properties of PE/V nanocomposite plates were characterized. Vermiculite has been modified to the role of nanofiller with organic dodecylamine (DA) compounds in various concentrations. Exfoliation of modified vermiculite nanofiller in PE was studied on the nanocomposite plates using X-ray diffraction analysis. The quality of nanofiller distribution in polymer matrix was observed using light microscopy. Changes in mechanical properties of the PE/VDA nano...
A filtration model taking particle-fiber as well as particle-particle interactions into account w... more A filtration model taking particle-fiber as well as particle-particle interactions into account was suggested and applied on a 3D simulation model of the nanofiber based filter, which was based on its SEM image. A theoretical study was done to evaluate the filtration efficiency as a function of number of particles, way of distributing the particles and the penetration profile through the filter. It was clearly shown that the cake formation has a significant effect on the filtration efficiency. Additionally, a visual representation of the cake formation was generated according the suggested model to get a better understanding of the cake morphology. Key-Words: Nanofiber Based Filter, Cake Formation, 3D Filtration Modeling, Electrospinning
Multi-wall carbon nanotube networks were prepared by process of filtration of CNT aqueous dispers... more Multi-wall carbon nanotube networks were prepared by process of filtration of CNT aqueous dispersions. CNT dispersions were prepared with help of surfactant system (Sodium dodecyl sulfate with amylalcohol) by ultrasonication. Three types of MWCNT tubes were used. The first were pure CNT material delivered by supplier. The other were chemically treated in aim to prepare CNT oxidised forms (1. acid solution of KMnO 4, 2. mixture of acids H 2SO 4 + HNO 3). It was found that chemical modification significantly changes properties of prepared carbon nanotube networks (“Buckypaper”). There were observed differences in porous structure between all of the forms analysed by SEM microscopy. Further, apparent density of prepared “Buckypapers” changes in respect of used CNT material leading to different porosity of Buckypapers. Electrical resistance is also affected by process of MWCNT oxidation together with its temperature dependence. Effect of compressive strain on electric resistance of mult...
The ever-increasing population has aroused demand for contraceptive chemicals which pollute the w... more The ever-increasing population has aroused demand for contraceptive chemicals which pollute the water reservoirs through industrial effluents. This has caused a severe threat to marine life and high concern about the availability of fresh drinkable water for people all over the world. Not only this, the unwanted intake of these water containing hormones leads to fertility disorder, rapid femininity, loss in male sperm count, high chances of breast, and ovarian cancer. Therefore, in this study, a one-step high-pressure liquid chromatography (HPLC) technique was devised for simultaneous detection and quantification of various estrogenic hormones from wastewater. Four representative hormones Estrone (E1), β-Estradiol (E2), Estriol (E3), and 17α-Ethinylestradiol (EE2) were used. To address the solubility of these hormones, a study was conducted in three solvents systems viz. ethanol, ethanol: water (20:80), and water, respectively. Similarly, calibration curves were made for these three solvent systems with regression coefficients ≥0.99. Interestingly, it was found that water can be used as a solvent for the estrogenic hormones at a detection limit as low as 5 µg/L, which makes this study quite significant.
Jaroslav Lev , Marek HOLBA , Libor KALHOTKA , Monika SZOSTKOVÁ , Dušan KIMMER d a ASIO spol. s r.... more Jaroslav Lev , Marek HOLBA , Libor KALHOTKA , Monika SZOSTKOVÁ , Dušan KIMMER d a ASIO spol. s r.o.,Tuřanka 1, 627 00 Brno, Czech Republic, EU, [email protected], b Institute of Botany, Academy of Science of the Czech Republic, v.v.i., Lidická 25/27, 657 20 Brno, Czech Republic EU, [email protected] b c Faculty of Agronomy of Mendelu in Brno, Zemědělská 1, 613 00 Brno, Czech Republic, EU, [email protected], [email protected]
Selected procedures permitting to prepare homogeneous nanofibre structures of the desired morphol... more Selected procedures permitting to prepare homogeneous nanofibre structures of the desired morphology by employing a suitable combination of variables during the electrospinning process are presented. A comparison (at the same pressure drop) was made of filtration capabilities of planar polyurethane nanostructures formed exclusively by nanofibres and space nanostructures having bead spacers or structures formed by a combination of microand nanofibres, through which ultrafine particles of ammonium sulphate 20 – 400 nm in size were filtered. The structures studied were described using a new digital image analysis technique based on black and white images obtained by scanning electron microscopy. More voluminous structures modified with distance microspheres and having a greater thickness and mass per square area of the material, i.e. structures possessing better mechanical properties, demanded so much in nanostructures, enable preparation of filters having approximately the same free v...
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