This page has only limited features, please log in for full access.
In this work, we tried to analyze dust loading behavior of polypropylene hollow fiber membranes using average pressure drop models. Hollow fiber membranes varying in fiber diameter were loaded with a standardized test dust to simulate particle-polluted air. We measured pressure drop development of the membranes at different flowrates and dust concentrations, and, after each experiment, the dust deposited on the membrane fibers was weighed to obtain dust holding capacity (DHC). The obtained experimental data was analyzed using various average pressure drop models and compared with average pressure drop obtained from pressure drop/dust load dependence using a curve fit. Exponential and polynomial fitting was used and compared. Pressure drop in relation to the dust load followed different trends depending on the experimental conditions and inner fiber diameter. At higher flowrate, the dependence was polynomial no matter what the fiber diameter. However, with higher fiber diameter at lower permeate velocities, the dependence was close to exponential curve and followed similar trends as observed in planar filter media. Dust-holding capacity of the membranes depended on the experimental conditions and was up to 21.4 g. However, higher dust holding capacity was impossible to reach no matter the experiment duration due to self-cleaning ability of the tested membranes.
Pavel Bulejko; Ondřej Krištof; Miroslav Dohnal. An Assessment on Average Pressure Drop and Dust-Holding Capacity of Hollow-Fiber Membranes in Air Filtration. Membranes 2021, 11, 467 .
AMA StylePavel Bulejko, Ondřej Krištof, Miroslav Dohnal. An Assessment on Average Pressure Drop and Dust-Holding Capacity of Hollow-Fiber Membranes in Air Filtration. Membranes. 2021; 11 (7):467.
Chicago/Turabian StylePavel Bulejko; Ondřej Krištof; Miroslav Dohnal. 2021. "An Assessment on Average Pressure Drop and Dust-Holding Capacity of Hollow-Fiber Membranes in Air Filtration." Membranes 11, no. 7: 467.
This work analyzes energy requirements for drawing the air through a hollow-fiber membrane (HFM) during air filtration. Polypropylene HFMs varying in inner fiber diameter (230 and 470μm) were used to separate the ASHRAE A2 fine test dust from a simulated particle laden environment. During the experiments, pressure drop, permeate velocity (air flowrate), fan frequency and power input were recorded. The obtained experimental data was analyzed using theoretical models relating pressure drop with power consumption necessary to overcome the membrane resistance. The results obtained for HFMs of different parameters (especially inner fiber diameter) were compared in terms of air flowrate and dust loading rate. Their influence on the energy consumption to operate the fan in the filtration process was then evaluated. The results have shown the smaller diameter HFMs have significantly higher energy consumption to operate the blower (about 180 Wh/m3) compared to larger diameter membrane (approx. 100 Wh/m3). This was despite higher surface area (0.95 m2) of lower diameter membrane compared to lower surface (0.43 m2) of HFMs with larger diameter. The general course of energy consumption during dust loading varied depending on the inner fiber diameter rather than on dust loading. This was obvious no matter of the dust loading rate (2, 4 and 6 g/hr), which seems to have negligible effect at the adopted experimental conditions a consumption of 113, 102 and 116 Wh/m3, respectively).
Pavel Bulejko. An analysis on energy demands in airborne particulate matter filtration using hollow-fiber membranes. Energy Reports 2021, 7, 2727 -2736.
AMA StylePavel Bulejko. An analysis on energy demands in airborne particulate matter filtration using hollow-fiber membranes. Energy Reports. 2021; 7 ():2727-2736.
Chicago/Turabian StylePavel Bulejko. 2021. "An analysis on energy demands in airborne particulate matter filtration using hollow-fiber membranes." Energy Reports 7, no. : 2727-2736.
This work aimed to study the pressure drop evolution of hollow-fiber membranes (HFMs) during aerosol loading. We tested two types of polypropylene HFMs varying in inner fiber diameter with an ASHRAE A2 test dust. Data was recorded including pressure drop, flowrate/permeate velocity and accumulated mass of particles until reaching the final pressure drop. The results showed a slow pressure drop increase even when loaded with extremely high (units of g/m3) dust concentrations. The membranes were easily cleanable simply by shaking, with a minimal residual pressure drop. The particle loading profile (pressure drop/dust load curve) was dependent on the inner diameter of hollow fibers and permeate velocity. The loading profile of a new HFM was independent of dust concentration. However, when a regenerated membrane was used, the dependence on the dust concentration was obvious. The same was true for the fouling rate, which was higher for the regenerated membrane. Theoretical and empirical models for dust cake pressure drop were in a strong disagreement with experiment data. In practical applications, they will be rather limited to a very specific low volume, or short-term high volume filtrations due to the higher pressure drops caused by the hollow-fiber geometry.
Pavel Bulejko; Ondřej Krištof; Tomáš Svěrák. Experimental and modeling study on fouling of hollow-fiber membranes by fine dust aerosol particles. Journal of Membrane Science 2020, 616, 118562 .
AMA StylePavel Bulejko, Ondřej Krištof, Tomáš Svěrák. Experimental and modeling study on fouling of hollow-fiber membranes by fine dust aerosol particles. Journal of Membrane Science. 2020; 616 ():118562.
Chicago/Turabian StylePavel Bulejko; Ondřej Krištof; Tomáš Svěrák. 2020. "Experimental and modeling study on fouling of hollow-fiber membranes by fine dust aerosol particles." Journal of Membrane Science 616, no. : 118562.
Spiral nozzles are widely used in wet scrubbers to form an appropriate spray pattern to capture the polluting gas/particulate matterwith the highest possible efficiency. Despite this fact, and a fact that it is a nozzle with a very atypical spray pattern (a full cone consisting of three concentric hollow cones), very limited amount of studies have been done so far on characterization of this type of nozzle. This work reports preliminary results on the spray characteristics of a spiral nozzle used for gas absorption processes. First, we experimentally measured the pressure impact footprint of the spray generated. Then effective spray angles were evaluated from the photographs of the spray and using the pressure impact footprint records via Archimedean spiral equation. Using the classical photography, areas of primary and secondary atomization were determined together with the droplet size distribution, which were further approximated using selected distribution functions. Radial and tangential spray velocity of droplets were assessed using the laser Doppler anemometry. The results show atypical behavior compared to different types of nozzles. In the investigated measurement range, the droplet-size distribution showed higher droplet diameters (about 1 mm) compared to, for example, air assisted atomizers. It was similar for the radial velocity, which was conversely lower (max velocity of about 8 m/s) compared to, for example, effervescent atomizers, which can produce droplets with a velocity of tens to hundreds m/s. On the contrary, spray angle ranged from 58° and 111° for the inner small and large cone, respectively, to 152° for the upper cone, and in the measured range was independent of the inlet pressure of liquid at the nozzle orifice.
Ondřej Krištof; Pavel Bulejko; Tomáš Svěrák. Experimental Study on Spray Breakup in Turbulent Atomization Using a Spiral Nozzle. Processes 2019, 7, 911 .
AMA StyleOndřej Krištof, Pavel Bulejko, Tomáš Svěrák. Experimental Study on Spray Breakup in Turbulent Atomization Using a Spiral Nozzle. Processes. 2019; 7 (12):911.
Chicago/Turabian StyleOndřej Krištof; Pavel Bulejko; Tomáš Svěrák. 2019. "Experimental Study on Spray Breakup in Turbulent Atomization Using a Spiral Nozzle." Processes 7, no. 12: 911.
Hollow-fiber membranes (HFMs) have widely been applied to many liquid treatment applications such as wastewater treatment, membrane distillation and membrane contactor/bioreactor applications. However, they have rarely been used for aerosol filtration thus far. In this work, we tested air filtration performance of air filter modules composed of polypropylene HFMs. The experimental results of most penetrating particle size (MPPS) and permeability were then compared with theoretically predicted values. Filtration efficiency and MPPS were measured using a monodisperse (20, 35, 50, 70, 100, 140, 280 and 400 nm) and a polydisperse aerosol (15–594 nm). Dimensionless permeability was predicted using models assuming isotropic 3D pore structure and compared with permeability measured using capillary flow porometry. Finally, an experiment to observe pressure drop with long-term particle loading was carried out. In the experiments with the monodisperse aerosol, no penetration was observed regardless of particle size. Therefore, face velocity was increased and high concentrations of the polydisperse aerosol were used to increase the penetration. The MPPS was then found to be 333 and 250 nm at a flowrate of 10 and 40 L/min, respectively. The MPPS model for diffusion and interception dominant regime proposed by Lee and Liu (1986) was closest to these results. Dimensionless permeability varied depending on the conditions for which the individual models were derived. For example, the RUC (representative unit cell) model underestimates the results while the results predicted using the empirical formula of Davies (1953) differ significantly from the measured values. The loading experiments have shown significantly prolonged fouling by high concentrations of submicron particles compared to conventional fibrous filters.
Pavel Bulejko; Ondřej Krištof; Mirko Dohnal; Tomáš Svěrák. Fine/ultrafine particle air filtration and aerosol loading of hollow-fiber membranes: A comparison of mathematical models for the most penetrating particle size and dimensionless permeability with experimental data. Journal of Membrane Science 2019, 592, 117393 .
AMA StylePavel Bulejko, Ondřej Krištof, Mirko Dohnal, Tomáš Svěrák. Fine/ultrafine particle air filtration and aerosol loading of hollow-fiber membranes: A comparison of mathematical models for the most penetrating particle size and dimensionless permeability with experimental data. Journal of Membrane Science. 2019; 592 ():117393.
Chicago/Turabian StylePavel Bulejko; Ondřej Krištof; Mirko Dohnal; Tomáš Svěrák. 2019. "Fine/ultrafine particle air filtration and aerosol loading of hollow-fiber membranes: A comparison of mathematical models for the most penetrating particle size and dimensionless permeability with experimental data." Journal of Membrane Science 592, no. : 117393.
This work aimed to determine filtration performance of polypropylene hollow-fiber membranes in removing submicron particles from air. Experiments were performed in a chamber simulating dust environment with synthetic submicron-size particles (micronized TiO2). Ahollow-fiber membrane with 300 fibers of a filtration area of 0.43 m2 was tested. By measuring number of particles in chamber (upstream) and on the suction side of the membrane (downstream), the filtration efficiency was determined. Two different weights of synthetic dust (50 and 100 mg) and two permeate velocities (15 and 30 cm/s) were used to compare their influence on particle collection efficiency. Particle counting was carried out using a TSI 3075 condensation particle counter connected to a TSI 3080 scanning mobility particle sizer in 32 particle size channels from 17 to 600 nm. Pressure drop evolution with intense particle loading was recorded and fouling of the membrane was observed after 25, 50 and 90 h of filtration using SEM. The results showed high efficiency, mostly higher than 99.9% with higher pressure drops compared to other materials on HEPA level.
Pavel Bulejko; Tomáš Svěrák; Mirko Dohnal; Jiří Pospíšil. Aerosol filtration using hollow-fiber membranes: Effect of permeate velocity and dust amount on separation of submicron TiO2 particles. Powder Technology 2018, 340, 344 -353.
AMA StylePavel Bulejko, Tomáš Svěrák, Mirko Dohnal, Jiří Pospíšil. Aerosol filtration using hollow-fiber membranes: Effect of permeate velocity and dust amount on separation of submicron TiO2 particles. Powder Technology. 2018; 340 ():344-353.
Chicago/Turabian StylePavel Bulejko; Tomáš Svěrák; Mirko Dohnal; Jiří Pospíšil. 2018. "Aerosol filtration using hollow-fiber membranes: Effect of permeate velocity and dust amount on separation of submicron TiO2 particles." Powder Technology 340, no. : 344-353.
Hollow-fiber membranes (HFMs) have been widely applied to many liquid treatment applications such as wastewater treatment, membrane contactors/bioreactors and membrane distillation. Despite the fact that HFMs are widely used for gas separation from gas mixtures, their use for mechanical filtration of aerosols is very scarce. In this work, we compared mathematical models developed for the prediction of air filtration efficiency by applying them on the structural parameters of polypropylene HFMs. These membranes are characteristic of pore diameters of about 90 nm and have high solidity, thus providing high potential for nanoparticle removal from air. A single fiber/collector and capillary pore approach was chosen to compare between models developed for fibrous filters and capillary-pore membranes (Nuclepore filters) based on three main mechanisms occurring in aerosol filtration (inertial impaction, interception and diffusion). The collection efficiency due to individual mechanisms differs significantly. The differences are caused by the parameters for which the individual models were developed, i.e., given values of governing dimensionless numbers (Reynolds, Stokes and Peclet number) and also given values of filter porosity and filter fiber diameter. Some models can be used to predict the efficiency of HFMs based on assumptions depending on the conditions and exact membrane parameters.
Pavel Bulejko. Numerical Comparison of Prediction Models for Aerosol Filtration Efficiency Applied on a Hollow-Fiber Membrane Pore Structure. Nanomaterials 2018, 8, 447 .
AMA StylePavel Bulejko. Numerical Comparison of Prediction Models for Aerosol Filtration Efficiency Applied on a Hollow-Fiber Membrane Pore Structure. Nanomaterials. 2018; 8 (6):447.
Chicago/Turabian StylePavel Bulejko. 2018. "Numerical Comparison of Prediction Models for Aerosol Filtration Efficiency Applied on a Hollow-Fiber Membrane Pore Structure." Nanomaterials 8, no. 6: 447.
This paper studies possibilities of alkali-activated fly ash (AAFA) for the preparation of systems with preserved certain porosity level. Such systems would be used for example as filtration barriers, which are commonly prepared by both energetically and economically expensive sintering process at high temperatures. Porosity preservation was facilitated by the use of only coarse fraction from fly ash particles together with the use of low water to fly ash ratio and pressure compaction. Two different doses of sodium hydroxide were used to alkali activate fly ash. Prepared specimens were moist cured at 95 °C for 24 hours. Porosity and binder phase among the fly ash grains were investigated using scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP) and capillary flow porosimetry (CFP). The results showed that it is possible to prepare AAFA-based porous systems and modify their properties by changing the activator dose.
Pavel Kejik; Vlastimil Bílek Jr.; Pavel Bulejko; Jan Hajzler; Matěj Březina; Lucie Galvánková; Lukas Kalina. Porous Systems Based on Alkali-Activated Fly Ash. Solid State Phenomena 2018, 276, 179 -184.
AMA StylePavel Kejik, Vlastimil Bílek Jr., Pavel Bulejko, Jan Hajzler, Matěj Březina, Lucie Galvánková, Lukas Kalina. Porous Systems Based on Alkali-Activated Fly Ash. Solid State Phenomena. 2018; 276 ():179-184.
Chicago/Turabian StylePavel Kejik; Vlastimil Bílek Jr.; Pavel Bulejko; Jan Hajzler; Matěj Březina; Lucie Galvánková; Lukas Kalina. 2018. "Porous Systems Based on Alkali-Activated Fly Ash." Solid State Phenomena 276, no. : 179-184.
This paper investigates the possibilities of the use of sodium hydroxide activated blast furnace slag for preparation of filtration barriers. The motivation for this research is searching for cheaper and more eco-friendly alternative to sintering, which is commonly used for filtration membranes preparation. Such an alternative could be alkaline activation, which is able to bind slag particles together. Low amount of activator, low water to slag (w/s) ratio together with pressure compaction was used to obtain microstructure with preserved continuous porosity. To confirm this presumption scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) analyses were carried out.
V Bílek; P Bulejko; P Kejík; J Hajzler; Jiří Másilko; J Bednárek; J Tkacz; Lukas Kalina. Potential use of blast furnace slag for filtration membranes preparation: A pilot study. IOP Conference Series: Materials Science and Engineering 2018, 379, 012012 .
AMA StyleV Bílek, P Bulejko, P Kejík, J Hajzler, Jiří Másilko, J Bednárek, J Tkacz, Lukas Kalina. Potential use of blast furnace slag for filtration membranes preparation: A pilot study. IOP Conference Series: Materials Science and Engineering. 2018; 379 (1):012012.
Chicago/Turabian StyleV Bílek; P Bulejko; P Kejík; J Hajzler; Jiří Másilko; J Bednárek; J Tkacz; Lukas Kalina. 2018. "Potential use of blast furnace slag for filtration membranes preparation: A pilot study." IOP Conference Series: Materials Science and Engineering 379, no. 1: 012012.
This work aimed to determine filtration performance of polypropylene hollow-fibre membranes (HFMs) for removing submicron particles from air. Experiments were performed in a glass chamber supplied with a nanoaerosol particles formed by burning incense sticks. Three types of HFMs varying in packing density, active filtration area and pore-size distribution were tested in an outside-in configuration. By measuring the number of particles upstream and downstream of the HFM, the filtration efficiency was determined. Three permeate velocities (5, 10 and 15 cm/s) were used to compare the velocity effect on filtration efficiency. Particle counting was carried out using a TSI 3075 condensation particle counter connected to a TSI 3080 scanning mobility particle sizer in 48 particle size channels from 18.1 to 100 nm. The results show high efficiency, mostly higher than 99% for particles above 60 nm size. The most penetrating particle sizes (MPPS) were between 35.9 and 40 nm at 5 cm/s with an efficiency of 82–86%. At permeate velocity of 10 and 15 cm/s, MPPS slightly decreased to range of 34.6–40 nm, with efficiency decreasing to 72–84% and 69–83%, respectively. The quality factor of HFMs was within the 2 to 28 kPa−1 range.
Pavel Bulejko; Mirko Dohnal; Jiří Pospíšil; Tomáš Svěrák. Air filtration performance of symmetric polypropylene hollow-fibre membranes for nanoparticle removal. Separation and Purification Technology 2018, 197, 122 -128.
AMA StylePavel Bulejko, Mirko Dohnal, Jiří Pospíšil, Tomáš Svěrák. Air filtration performance of symmetric polypropylene hollow-fibre membranes for nanoparticle removal. Separation and Purification Technology. 2018; 197 ():122-128.
Chicago/Turabian StylePavel Bulejko; Mirko Dohnal; Jiří Pospíšil; Tomáš Svěrák. 2018. "Air filtration performance of symmetric polypropylene hollow-fibre membranes for nanoparticle removal." Separation and Purification Technology 197, no. : 122-128.
Pavel Bulejko; Eliška Stránská. The effect of initial moisture content of cation-exchange resin on the preparation and properties of heterogeneous cation-exchange membranes. Materials Chemistry and Physics 2018, 205, 470 -479.
AMA StylePavel Bulejko, Eliška Stránská. The effect of initial moisture content of cation-exchange resin on the preparation and properties of heterogeneous cation-exchange membranes. Materials Chemistry and Physics. 2018; 205 ():470-479.
Chicago/Turabian StylePavel Bulejko; Eliška Stránská. 2018. "The effect of initial moisture content of cation-exchange resin on the preparation and properties of heterogeneous cation-exchange membranes." Materials Chemistry and Physics 205, no. : 470-479.
This work deals with the separation of CO2 gaseous pollutant from gas mixtures to a water solution using the laboratory contactor. The laboratory set process parameters showed the rate of carbon dioxide transition through the interface in a so promising level the contactor separators can be considered as a very promising pathway to reduce the content of this greenhouse gas from the air.
T Sverak; Pavel Bulejko; J Ostrezi; Ondrej Kristof; Josef Kalivoda; P Kejik; Katerina Mayerova; M Adamcik. Separation of gaseous air pollutants using membrane contactors. IOP Conference Series: Earth and Environmental Science 2017, 92, 012061 .
AMA StyleT Sverak, Pavel Bulejko, J Ostrezi, Ondrej Kristof, Josef Kalivoda, P Kejik, Katerina Mayerova, M Adamcik. Separation of gaseous air pollutants using membrane contactors. IOP Conference Series: Earth and Environmental Science. 2017; 92 (1):012061.
Chicago/Turabian StyleT Sverak; Pavel Bulejko; J Ostrezi; Ondrej Kristof; Josef Kalivoda; P Kejik; Katerina Mayerova; M Adamcik. 2017. "Separation of gaseous air pollutants using membrane contactors." IOP Conference Series: Earth and Environmental Science 92, no. 1: 012061.
The main effort of this work was to evaluate the situation of the atmosphere in selected regions of Brno during the years 2009-2013 and to estimate health risks which might come up due to the increased concentrations of airborne particulate matter. PM10 samples were collected in four areas varying in degree of automobile traffic using automatic and gravimetric sampling methods. PM10 concentrations were assessed using Spearman's rank correlation coefficient. Health risks were estimated based on calculation of relative risks and population for four health endpoints. The selected health outcomes were premature mortality, cardiovascular disease, respiratory disease, and chronic bronchitis. The highest PM10 concentrations were measured in two regions with high traffic loads T1, T2 and background region B2. The values were 34.33 ± 11.52 µg·m-3 in 2010, 34.87 ± 12.03 µg·m-3 in 2013 and 34.52 ± 8.81 µg·m-3 in 2009, respectively. The highest correlation was between T1 and T2 having Spearman's correlation coefficient 0.888 followed by T1-B1 pair with coefficient 0.886. For all health outcomes, the highest health effect of PM (E) was determined for T2 site in 2010 which was 48 ± 14, 49 ± 21, 44 ± 19 and 24 ± 10 for premature mortality, cardiovascular disease, respiratory disease, and chronic bronchitis, respectively. The concentrations are highly correlated, especially in traffic regions. The annual concentrations did not exceed the legislation limit but 24-hours limit was exceeded more than two times in several cases. The highest number of cases with a given health outcome was estimated in traffic regions especially for cardiovascular disease and premature mortality.
Pavel Bulejko; Vladimír Adamec; Robert Skeřil; Barbora Schullerova; Vladimír Bencko. Levels and Health Risk Assessment of PM10 Aerosol in Brno, Czech Republic. Central European Journal of Public Health 2017, 25, 129 -134.
AMA StylePavel Bulejko, Vladimír Adamec, Robert Skeřil, Barbora Schullerova, Vladimír Bencko. Levels and Health Risk Assessment of PM10 Aerosol in Brno, Czech Republic. Central European Journal of Public Health. 2017; 25 (2):129-134.
Chicago/Turabian StylePavel Bulejko; Vladimír Adamec; Robert Skeřil; Barbora Schullerova; Vladimír Bencko. 2017. "Levels and Health Risk Assessment of PM10 Aerosol in Brno, Czech Republic." Central European Journal of Public Health 25, no. 2: 129-134.
Pavel Bulejko Pavel Bulejko; Vlastimil Bílek Jr. Vlastimil Bílek Jr.. Influence of chemical additives and curing conditions on the mechanical properties and carbonation resistance of alkali-activated slag composites. Materiali in tehnologije 2017, 51, 49 -53.
AMA StylePavel Bulejko Pavel Bulejko, Vlastimil Bílek Jr. Vlastimil Bílek Jr.. Influence of chemical additives and curing conditions on the mechanical properties and carbonation resistance of alkali-activated slag composites. Materiali in tehnologije. 2017; 51 (1):49-53.
Chicago/Turabian StylePavel Bulejko Pavel Bulejko; Vlastimil Bílek Jr. Vlastimil Bílek Jr.. 2017. "Influence of chemical additives and curing conditions on the mechanical properties and carbonation resistance of alkali-activated slag composites." Materiali in tehnologije 51, no. 1: 49-53.
This paper focuses on the transport and mechanical properties of ion-exchange membranes (IEMs) in an aqueous NaOH solution. Heterogeneous IEMs based on styrene–divinylbenzene and polyethylene reinforced with polyester (PES) or polyamide (PAD) fabric were studied. The IEMs were exposed to a 5% NaOH solution for 30 and 90 days and the changes in electrochemical resistance, transport number and permselectivity were evaluated. Moreover, the structure of the IEMs was observed after exposure and their mechanical properties were evaluated. The results show that NaOH solution has the most damaging effect, especially to PES cloth and the membrane as whole, mainly due to dimensional changes. Furthermore, changes in electrochemical resistance were observed.
Pavel Bulejko; Eliška Stránská; Kristýna Weinertová. Electrochemical and mechanical stability of ion-exchange membranes in alkaline solution. Chemical Papers 2017, 71, 1303 -1309.
AMA StylePavel Bulejko, Eliška Stránská, Kristýna Weinertová. Electrochemical and mechanical stability of ion-exchange membranes in alkaline solution. Chemical Papers. 2017; 71 (7):1303-1309.
Chicago/Turabian StylePavel Bulejko; Eliška Stránská; Kristýna Weinertová. 2017. "Electrochemical and mechanical stability of ion-exchange membranes in alkaline solution." Chemical Papers 71, no. 7: 1303-1309.
Tomáš Svěrák; Pavel Bulejko; Ondřej Krištof; Pavel Kejík; Josef Kalivoda; Jaroslav Horský. Covering ability of aluminum pigments prepared by milling processes. Powder Technology 2017, 305, 396 -404.
AMA StyleTomáš Svěrák, Pavel Bulejko, Ondřej Krištof, Pavel Kejík, Josef Kalivoda, Jaroslav Horský. Covering ability of aluminum pigments prepared by milling processes. Powder Technology. 2017; 305 ():396-404.
Chicago/Turabian StyleTomáš Svěrák; Pavel Bulejko; Ondřej Krištof; Pavel Kejík; Josef Kalivoda; Jaroslav Horský. 2017. "Covering ability of aluminum pigments prepared by milling processes." Powder Technology 305, no. : 396-404.
This work deals with resistance of ion-exchange membranes in selected chemical solutions. Specimens of heterogeneous membranes were analyzed after exposure to chemically aggressive agents such as nitric acid, sodium hydroxide, etc. The analyses were carried out after period up to 6 months. The chemical resistance was evaluated from the mechanical and electrochemical property changes’ point of view before and after exposure. The tested materials were not only the membranes themselves but also their individual components, i.e., ion-exchange resins from various manufacturers and polyester reinforcing fabrics. The results show that exposure to NaOH solution has the most damaging effect especially on reinforcing fabric and a membrane as whole due mainly to dimension changes. The same stands for electrochemical resistance of the membrane and permselectivity. Ion-exchange capacity remains almost the same after exposure.
Pavel Bulejko; Eliška Stránská; Kristýna Weinertová. Properties and structure of heterogeneous ion-exchange membranes after exposure to chemical agents. Journal of Solid State Electrochemistry 2016, 21, 111 -124.
AMA StylePavel Bulejko, Eliška Stránská, Kristýna Weinertová. Properties and structure of heterogeneous ion-exchange membranes after exposure to chemical agents. Journal of Solid State Electrochemistry. 2016; 21 (1):111-124.
Chicago/Turabian StylePavel Bulejko; Eliška Stránská; Kristýna Weinertová. 2016. "Properties and structure of heterogeneous ion-exchange membranes after exposure to chemical agents." Journal of Solid State Electrochemistry 21, no. 1: 111-124.
This work aimed to determine the seasonal variations of polycyclic aromatic hydrocarbons (PAHs) in airborne PM10 at two background sites (Masná-MS, Líšeň-LN) in Brno over a 5-year period (2009-2013). Samples were collected on quartz filters using a low-volume sampler by continual filtration. Concentrations of PAHs in collected PM10 samples were determined using a gas chromatography with a mass spectrometer as a detector. A different number of PAHs were determined to be at each site, i.e., 11 PAHs at the MS site and six PAHs at the LN site, and similarities between them were identified using non-parametric analysis of variance. Potential sources were identified using principal component analysis (PCA) and PAHs diagnostic ratios. The work also focused on health risk assessment. This was estimated using toxic equivalent factors to calculate individual lifetime cancer risk, which quantifies risk of exposure to PAHs for specific age groups. The average 11-PAH concentrations in M|S site annually ranged from 19.28 ± 19.02 ng m(-3) (2011) to 40.37 ± 21.35 ng m(-3) (2013). With regard to the LN site, the average six-PAH concentrations annually ranged from 3.64 ± 3.87 ng m(-3) (2009) and 5.27 ± 6.19 ng m(-3) (2012). PCA and diagnostic ratios indicate the main sources to be traffic emissions and coal combustion. Health risk assessment showed carcinogenic risk under limit value in all cases.
Pavel Bulejko; Vladimír Adamec; Barbora Schüllerová; Robert Skeřil. Levels, sources, and health risk assessment of polycyclic aromatic hydrocarbons in Brno, Czech Republic: a 5-year study. Environmental Science and Pollution Research 2016, 23, 20462 -20473.
AMA StylePavel Bulejko, Vladimír Adamec, Barbora Schüllerová, Robert Skeřil. Levels, sources, and health risk assessment of polycyclic aromatic hydrocarbons in Brno, Czech Republic: a 5-year study. Environmental Science and Pollution Research. 2016; 23 (20):20462-20473.
Chicago/Turabian StylePavel Bulejko; Vladimír Adamec; Barbora Schüllerová; Robert Skeřil. 2016. "Levels, sources, and health risk assessment of polycyclic aromatic hydrocarbons in Brno, Czech Republic: a 5-year study." Environmental Science and Pollution Research 23, no. 20: 20462-20473.
Aluminum powders are used in porous concrete constructional elements production, in coating compositions and varnish media industry, introduction of printing inks and finally but not less in chemical and pyrotechnical production. The purpose of atypical grinding processes is to obtain fine metal powders of extremely high specific surface which should be evaluated by the parameter of hiding power ability of pigment materials. This paper shows the development of this basic parameter of metal pigment products under the wet process of milling using a pilot-plant ball mill, as a function of milling time and turns of mill drum as one of the basic parameters.
Tomáš Svěrák; Pavel Bulejko; Kateřina Sikorová; Pavel Kejik; Ondrej Kristof; Miroslav Raudenský. Hiding Power of Aluminum Metal Pigments Development in the Ball Mill Grinding Process. Solid State Phenomena 2015, 244, 19 -25.
AMA StyleTomáš Svěrák, Pavel Bulejko, Kateřina Sikorová, Pavel Kejik, Ondrej Kristof, Miroslav Raudenský. Hiding Power of Aluminum Metal Pigments Development in the Ball Mill Grinding Process. Solid State Phenomena. 2015; 244 ():19-25.
Chicago/Turabian StyleTomáš Svěrák; Pavel Bulejko; Kateřina Sikorová; Pavel Kejik; Ondrej Kristof; Miroslav Raudenský. 2015. "Hiding Power of Aluminum Metal Pigments Development in the Ball Mill Grinding Process." Solid State Phenomena 244, no. : 19-25.