Wyniki wyszukiwania - BazTech

1

Warunki pirolizy a właściwości fizyczno-chemiczne biowęgla pochodzenia roślinnego

Wolański Błażej, Świechowski Kacper, Kierzek Krzysztof, Opaliński Sebastian

Przemysł Chemiczny

|

2024

|

T. 103, nr 4

541--544

PL

Biowęgiel (BC) od 2013 r. jest legalnym dodatkiem paszowym na terenie Unii Europejskiej. W dostępnej literaturze są przykłady badań dotyczących wykorzystania BC w żywieniu zwierząt, ale brak dokładnej charakterystyki zastosowanych biowęgli, obejmującej takie parametry, jak powierzchnia właściwa i wielkość porów, kluczowych, biorąc pod uwagę mechanizm wiązania toksyn przez BC. Przedstawiono charakterystyki BC otrzymanych ze słomy pszennej (SP) i zrębków drewna bukowo-dębowego (DBD). BC zostały wytworzone w procesie pirolizy w temp. 600°C i 900°C. W biowęglach uzyskanych ze słomy pszennej oraz zrębków drewna bukowo-dębowego dominowały pory o szerokości 0,6-1,8 nm (adsorbenty mikroporowate), a powierzchnia właściwa (metoda BET) wynosiła 267-578 m²/g.

EN

Beech and oak wood chips and wheat straw were pyrolyzed at 600 or 900°C. Nitrogen adsorption isotherms were detd. for the obtained biochars. The BET and QSDFT methods were used to det. the porosity parameters (sp. surface area, vol. and pore width). As the pyrolysis temp. increased, the sp. surface area of biochars increased significantly, regardless of the adsorption model used (BET or QSDFT). The obtained biochars were dominated by micropores (0.6-1.8 nm) and specific surface areas (BET method) was ranging from 267 to 578 m²/g. Anal. of the properties of biochars showed that the results obtained using these measurement methods differed.

2

Estimation of Metal Foam Microstructure Parameters for Maximum Sound Absorption Coefficient in Specified Frequency Band Using Particle Swarm Optimisation

Madvari Rohollah Fallah, Sharak Mohsen Niknam, Tehrani Mahsa Jahandideh, Abbasi Milad

Archives of Acoustics

|

2022

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Vol. 47, No. 1

33--42

EN

The study aims to estimate metal foam microstructure parameters for the maximum sound absorption coefficient (SAC) in the specified frequency band to obtain optimum metal foam fabrication. Lu’s theory model is utilised to calculate the SAC of metallic foams that refers to three morphological parameters: porosity, pore size, and pore opening. After Lu model validation, particle swarm optimisation (PSO) is used to optimise the parameters. The optimum values are obtained at frequencies 250 to 8000 Hz, porosity of 50 to 95%, a pore size of 0.1 to 4.5 mm, and pore opening of 0.07 to 0.98 mm. The results revealed that at frequencies above 1000 Hz, the absorption efficiency increases due to changes in the porosity, pore size, and pore opening values rather than the thickness. However, for frequencies below 2000 Hz, increasing the absorption efficiency is strongly correlated with an increase in foam thickness. The PSO is successfully used to find optimum absorption conditions, the reference for absorbent fabrication, on a frequency band 250 to 8000 Hz. The outcomes will provide an efficient tool and guideline for optimum estimation of acoustic absorbents.

3

The Removal of Reactive Red 141 From Wastewater: A Study of Dye Adsorption Capability of Water-Stable Electrospun Polyvinyl Alcohol Nanofibers

Akduman Çigdem, Morsümbül Seniha, Akçakoca Kumbasar Emriye Perrin

Autex Research Journal

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2021

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Vol. 21, no. 1

20--31

EN

The dye production and its use in textile and related industries resulted in discharge of dye to wastewater. Adsorption for color removal is known as equilibrium separation process, and the resultant decolorization is influenced by physicochemical factors such as adsorbent surface area. The nanofiber membranes prepared by the electrospinning method have controllable nanofiber diameter and pore size distribution (PSD) with a high surface area to volume or mass ratio. In this study, polyvinyl alcohol (PVA) nanofibrous membranes were prepared by the electrospinning method at different collection times such as 3, 5 and 10 h and heat fixated at 130, 150 and 170°C for 10 min, and then, the adsorption capability of PVA nanofiber membranes for Reactive Red 141 from aqueous solution was investigated. In order to make PVA nanofibers stable to water, the nanofibrous membranes were chemically cross-linked by a polycarboxylic acid (1,2,3,4 butanetetracarboxylic acid (BTCA)). PVA nanofibrous membranes were characterized by scanning electron microscopy, thermogravimetric analysis, swelling tests and pore size analysis. The results indicated that BTCA crosslinking improved the thermal and water stability of the nanofibrous structure but has no significant effect on the pore sizes of the membranes. Adsorption of Reactive Red 141 was studied by the batch technique, and it was observed that PVA nanofibers removed approximately >80% of the dye.

4

Study on the Relationship Between Structure Parameters and Filtration Performance of Polypropylene Meltblown Nonwovens

Xiao Yuanxiang, Sakib Nazmus, Yue Zhonghua, Wang Yan, Cheng Si, You Jianmin, Militky Jiri, Venkataraman Mohanapriya, Zhu Guocheng

Autex Research Journal

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2020

|

Vol. 20, no. 4

366--371

EN

In this study, polypropylene meltblown nonwoven fabrics with different structure parameters such as fiber diameter, pore size, and areal density were prepared by the industrial production line. The morphology of meltblown nonwoven fibers was evaluated by using scanning electron microscope, and the diameter of fibers was analyzed by using image-pro plus software from at least 200 measurements. The pore size of nonwoven fabric was characterized by a CFP-1500AE type pore size analyzer. The filtration efficiency and pressure drop were evaluated by TSI8130 automatic filter. The results showed that the pressure drop of nonwoven fabrics decreased with the increase in pore size; the filtration efficiency and the pressure drop had a positive correlation with the areal density. However, when the areal density is in the range of 27–29 g/m2, both filtration efficiency and pressure drop decreased with the increase of areal density; when the areal density was kept constant, the filtration efficiency decreased as the pore size decreased; when the pore size of the meltblown nonwoven fabric is less than 17 μm, the filtration efficiency increased as the pore diameter decreased; when the pore diameter of the nonwoven fabric is larger than 17 μm. In a wide range, the pressure drop decreased as the fiber diameter decreased.

5

Introducing a Newly Developed Fabric for Air Filtration

Hakam Mohamed, Hashima Wael, Elhawary Ibrahim, Elgeiheini Adel

Autex Research Journal

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2020

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Vol. 20, no. 2

148--154

EN

Woven and nonwoven fabrics present filtration efficiency higher than other air filtration media. Fabrics are selected according to air flow conditions and particle characteristics. The majority of air filtration media are nonwoven fabrics because of their cost, but they need high filtration area for high efficiency. Modified construction of woven fabric introduces high performance in air filtration and decreases filter size, which tends to have better competition abilities. The designed fabrics have considerable thickness and suitable pore characteristics by applying roving instead of weft yarns. Four factors (roving count and their turns per inch, picks per inch and fabric designs) were varied in order to study the effect of these factors on their performance in filtration. Optimum operating conditions for a determined range of air permeability and pore size were obtained.

6

Mechanical response at peri-implant mandibular bone for variation of pore characteristics of implants: A Finite Element Study

Sarkar Sulagna, Sahu Tikeshwar Prasad, Datta Arijit, Chandra Nimesh, Chakraborty Arindam, Datta Pallab, Majumder Santanu, Chowdhury Amit Roy

Acta of Bioengineering and Biomechanics

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2019

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Vol. 21, no. 2

83--93

EN

In this paper, the mechanical response of generic dental implants having calculated porosities with varying pore-sizes has been evaluated. The purpose of this study was to compare the developed stress-strain of designed porous implants (i.e., stress at the implant and strain at the peri-implant bone) with that of the non-porous implant. Methods: 3D model of a mandible was prepared from CT scan data and nine generic dental implant models have been designed having 10%, 20%, and 30% porosity with 500, 700, and 900 micron pore size along with a non-porous model for carrying out FE analyses. First, failure analyses of implants, under a biting force of 250 N have been performed. Next, the remaining implants have been further evaluated under average compressive chewing load of 100 N, for mechanical responses at bone-implant interface. Results: Von Mises strain at the peri-implant mandibular bone increases with the increase in percentage porosity of the implant material and maximum implant stress remained much below the yield stress level. Conclusion: Implant stiffness and compressive strength vary as a function of porosity and pore size. Strain obtained on the peri-implant bone is sufficient enough to facilitate better bone growth with the 700 micron pore size and 30% porosity, thus reducing the effect of stress shielding.

7

Wpływ struktury i porowatości wybranych materiałów filtracyjnych stosowanych w analizie grawimetrycznej na skuteczność zatrzymywania nanocząstek

Sobiech P., Jakubiak S., Oberbek P., Kozikowski P., Jankowski T.

Rocznik Ochrona Środowiska

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2018

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Tom 20, cz. 2

1402--1417

PL

W artykule przedstawiono wyniki badań dotyczących zatrzymywania nanocząstek grafitu na filtrach o różnej strukturze, które wykorzystywane są w analizie grawimetrycznej. Zbadano trzy poliwęglanowe membrany filtracyjne Nuclepore o deklarowanej wielkości porów 0,2 µm, 1 µm oraz 5 µm. Wyniki porównano z rezultatami otrzymanymi dla membran filtracyjnych z nitrocelulozy o deklarowanej wielkości porów 0,8 µm, a także dla filtrów z włókna szklanego o współczynniku retencji 1,6 µm. Podczas badania filtry zamontowane były w próbnikach IOM (SKC) wyposażonych w nasadki kalibracyjne. Aerozol zawierający nanocząstki grafitu kierowany na filtry generowany był za pomocą generatora GFG 1000 (Pallas). Generowane cząstki były w atmosferze argonu i nie były rozcieńczane powietrzem. Częstotliwość iskrzenia między elektrodami grafitu podczas badań wynosiła ok. 25Hz. W celu uzyskania jednakowego strumienia objętości aerozolu na wszystkich próbnikach, aerozol zasysany był przez pompki indywidualne Gilian 5000 (Sensidyne), które posiadają charakterystyki ciśnieniowe umożliwiające realizację eksperymentu przez 2 godziny przy przepływie 1 dm3/min. Pompki posiadają stabilizację przepływu i system sygnalizację zmianę wartości większą niż 5%. Na próbnikach IOM z zamontowanymi filtrami mierzone były spadki ciśnienia. Do tego celu wykorzystano przetworniki różnicy ciśnień P26 firmy Halstrup Walcher. Aerozol zawierający nanocząstki został poddany analizie za pomocą systemu analizy wymiarowej SMPS, składającego się klasyfikatora elektrostatycznego 3082 i kondensacyjnego licznika cząstek UCPC 3082 (TSI). Maksimum ilości uzyskano dla cząstek o średnim wymiarze 156,8 nm. Zbadane filtry pomiarowe charakteryzowały się zbliżoną masą zatrzymywanych nanocząstek grafitu. Różnica wartości średnich wynosiła 14,1%. Uwzględniając odchylenia standardowe największa różnica zebranej masy cząstek na filtrach wynosiła 38,3%. Największy przyrost masy krążków odnotowano dla filtra o deklarowanej wielkości porów równej 1 µm, najmniejszy natomiast na membranie o deklarowanej średnicy porów 5 µm i włókninie z włókien szklanych. Największym początkowym oporem przepływu charakteryzowała się membrana 0,2 µm (10,6 kPa), najmniejszym natomiast membrana 5 µm (0,29 kPa). Dla obydwu tych membran zaobserwowano szybki wzrost oporów w początkowym okresie. Dla membrany 0,2 µm w ciągu pierwszych piętnastu sekund opory przepływu wzrosły o prawie 2,5 kPa, po czym tempo przyrostów zmalało. W przypadku membrany 5 µm bardzo dynamiczny wzrost oporów przepływu obserwowano przede wszystkim w pierwszych kilkunastu minutach. W ciągu pierwszych dziesięciu minut opory przepływu wzrosły aż o ok. 10 kPa. Dla pozostałych trzech filtrów nie zarejestrowano tak znaczących wzrostów oporu podczas trwania badania. Największe końcowe spadki ciśnienia na filtrze odnotowano na membranie Nuclepore o deklarowanej wielkości porów 5 µm. Wynika to z faktu, iż średnica porów, znacznie większa od wielkości cząstek oraz relatywnie niewielka ilość porów przypadająca na centymetr kwadratowy, sprzyjają wnikaniu cząstek w głąb porów oraz zatrzymywaniu cząstek na ich granicy, co skutkuje zatykaniem filtra. W warunkach eksperymentu najbardziej odpowiednie do poboru nanocząstek grafitu okazały się filtry Nuclepore 1 µm oraz filtr z nitrocelulozy 0,8 µm.

EN

Influence of Structure and Porosity of Selected Filtration Materials Used in Gravimetric Analysis on the Retention Efficiency of Nanoparticles The article presents the research findings on the retention of graphite nanoparticles on filters of various structures used in gravimetric analysis. Three Nuclepore polycarbonate membranes with declared pore sizes of 0.2 µm, 1 µm and 5 µm were studied. The findings were compared with those obtained for cellulose nitrate membrane filters with the declared pore size of 0.8 µm as well as for glass microfiber filters with the retention range of 1.6 µm. During the experiments filters were mounted on IOM samplers (SKC) equipped with calibration caps. The aerosol containing graphite nanoparticles directed at the filters was generated with a GFG 1000 (Pallas) generator. The particles were generated in argon environment and they were not diluted with air. The spark frequency between the graphite electrodes during the research was 25 Hz. In order to obtain a uniform aerosol volume flow rate on all samplers, the aerosol was sucked by individual Gilian 5000 (Sensidyne) suction pumps with pressure characteristics rendering it possible to conduct the research for 2 hours at the flow of 1 dm3/min. The pumps have flow stabilizers and signal any change of value exceeding 5%. Pressure drops were measured on IOM samplers with the filters. P26 Halstrup Walcher differential pressure transmitters were used for this purpose. The aerosol containing the nanoparticles was analyzed using the SMPS scanning mobility particle sizer spectrometer comprising of 3082 electrostatic classifier and the UCPC 3082 condensation particle counter (TSI). The maximum quantity was obtained for particles of 156.8 nm in size on average. The studied measurement filters were characterized by similar masses of retained graphite nanoparticles. The difference between the average values was 14.1%. Having considered the standard deviations, the biggest difference of retained particle mass on the filters amounted to 38.3%. The biggest mass gain of the discs was recorded for the filter with the declared pore size of 1 µm, whereas the smallest for the membrane with the declared pore diameter of 5 µm and for the glass fibre filter. The 0.2 µm (10.6 kPa) membrane was characterized by the biggest initial flow resistance, whereas the 5 µm (0.29 kPa) one -– by the smallest. For both membranes, a rapid flow resistance increase during the initial period was recorded. For the 0.2 µm membrane, during the first fifteen seconds the flow resistance increased by nearly 2.5 kPa, at which point the increase pace decelerated. In the case of the 5 µm membrane, a very dynamic flow resistance increase was recorded primarily during the first dozen minutes. During the first 10 minutes the flow resistance increased by approximately 10 kPa. In the course of the research, such significant flow resistance increases were not recorded for the remainder of the filters. The biggest final filter pressure drops were recorded for the Nuclepore membrane with declared pore size of 5 µm. This is related to the fact that average pore diameter is much larger than particle diameter and relatively small number of pore per centimeter square. This leads to penetration of particles inside the pores, their retention on pore edge, which leads to clogging of the filter. During the experiment, Nuclepore 1 μm and 0,8 μm cellulose nitrate membrane filters proved to be the most suitable for collecting graphite nanoparticles.

8

Badanie różnych typów skał klastycznych metodą NMR przy zastosowaniu spektrometrów pracujących z częstotliwością rezonansową 2 MHz, 8 MHz i 23 MHz

Klaja J., Drabik K., Przelaskowska A., Kulinowski P.

Nafta-Gaz

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2017

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R. 73, nr 3

151--156

PL

Wykonywanie badań metodą magnetycznego rezonansu jądrowego na próbkach skał wymaga uwzględnienia ich specyfiki (np. rozmiar porów, skład mineralny, w szczególności zawartość minerałów ilastych, właściwości filtracyjne, zawartość minerałów żelazistych). Omówiono szereg zastosowań spektrometrów pracujących z częstotliwością rezonansową 2 MHz, 8 MHz i 23 MHz, wyposażonych w różne sondy pomiarowe, dające możliwość dopasowania spektrometru i sekwencji pomiarowych do charakteru badanej próbki. Autorzy koncentrują się na różnych aspektach wyznaczania porowatości oraz identyfikacji płynów złożowych dla próbek różnych typów skał klastycznych.

EN

The application of nuclear magnetic resonance (NMR) for the evaluation of rock core samples, requires taking into account, their specific features, e.g. pore size, illite composition, filtration properties, concentration of iron containing minerals. Measurements were performed using 2, 8 and 23 MHz NMR spectrometers – core analyzers – equipped with various probeheads. It allowed matching the spectrometer and pulse sequence parameters, to the characteristics of the sample. The authors concentrated on several aspects of porosity assessment and fluid typing for various clastic sedimentary rock samples.

9

Significance of porosity and pore accessibility for the selection of Ion exchange adsorbents for chromatographic purification of macromolecules

Umesh M., Arvind M.

Acta Chromatographica

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2017

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Vol. 29, no. 1

5--24

EN

Selection of adsorbent for the development of purification process for biomolecules is crucial due to the requirement of large number of binding sites and adsorption area. Considering this, porous structure with high charge density is selected as an adsorbent for macromolecule purification. Such selection may provide high static binding capacity but causes loss of separation performance due to improper porosity of adsorbent in comparison to solute sizes involved. To address this problem for the screening of adsorbent, this work reports adsorbent selection procedure on the basis of adsorbent pore diameter (dp), solute hydrodynamic dimensions (RH), and flow velocity in support of binding capacity. Towards that end, this study evaluated the pore accessibility performance of varying characteristics adsorbents using tracers like acetone, lysozyme, and bovine serum albumin (BSA) by designing nonbinding conditions. All screened adsorbents showed certain loss of total surface area depending on the solute dimensions and pore size. Sepharose type adsorbents showed accessible area loss up to 25% for lysozyme and 50% for BSA. Sepabeads type showed 30% loss, while macroporous UNO type showed only 7% loss of surface area for lysozyme. The study correlates accessibility with size ratio β (dp/RH). The value of β > 38 is found to be required for the accessibility of total pore area and optimum separation performance of ion exchangers investigated. Accessibility and β provide useful information for the selection of suitable adsorbent for the purification of macromolecules.

10

Kinetic study of CO2 reaction with CaO by a modified random pore model

Nouri S. M. M., Ebrahim H. A.

Polish Journal of Chemical Technology

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2016

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Vol. 18, nr 1

93--98

EN

In this work, a modified random pore model was developed to study the kinetics of the carbonation reaction of CaO. Pore size distributions of the CaO pellets were measured by nitrogen adsorption and mercury porosimetry methods. The experiments were carried out in a thermogravimeter at different isothermal temperatures and CO2 partial pressures. A fractional concentration dependency function showed the best accuracy for predicting the intrinsic rate of reaction. The activation energy was determined as 11 kcal/mole between 550–700°C. The effect of product layer formation was also taken into account by using the variable product layer diffusivity. Also, the model was successfully predicted the natural lime carbonation reaction data extracted from the literature.

11

Optimal Features of Porosity of Ti Alloys Considering their Bioactivity and Mechanical Properties

Sobieszczyk S.

Advances in Materials Science

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2010

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Vol. 10, nr 2(24)

20-30

EN

This article reviews the influence of porosity and pore sizes of titanium and titanium alloys, used as orthopaedic materials, on bioactivity and mechanical properties of the porous structures. The optimal features of porous titanium scaffolds allow the reconstruction and regeneration of bone tissue in load-bearing applications.

12

Klasyfikacja wielkości porów na podstawie metody mikrotomografii rentgenowskiej

Zalewska J., Dohnalik M.

Nafta-Gaz

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2009

|

R. 65, nr 12

947--952

PL

W artykule przedstawiono wyniki pomiarów porowatości całkowitej i podjęto próbę klasyfikacji wielkości porów ze względu na ich objętość, dla przykładowych dwóch próbek skał węglanowych pochodzących z utworów dolomitu głównego. Porowatość i rozkład wielkości porów określano z użyciem mikrotomografu rentgenowskiego oraz komputerowych technik obrazowania. Do wykonania pomiarów wykorzystano system Benchtop z wiązką stożkową.

EN

The study presents total porosity measurements results and an attempt of pore sizes classification based on their volume, for exemplary two samples of carbonate rocks of Main Dolomite origin. Porosity and pore size distribution have been determined by means of X-ray microtomography scanner and computed imaging techniques. Benchtop system with fan type beam was used for the measurements.

13

Surface microstructure and specific surface area of pure and Na-substituted gyrolite

Baltakys K., Siauciunas R., Kitrys S.

Materials Science Poland

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2008

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Vol. 26, No. 3

633--645

EN

Pure gyrolite was synthesized within 32 h at 200 °C from a stoichiometric composition (the molar ratio CaO/SiO2 was equal to 0.66 with water/solid ratio of the suspension equal to 10.0) of the initial CaO and SiO2źnH2O mixture. Meanwhile, Na-substituted gyrolite was synthesized twice quicker – within 16 h at 200 °C. These compounds were characterized by XRD, STA, FT-IR, SEM/EDS and BET analysis. It was found that gyrolite is a mesoporous material. Its specific surface area SBET = 143.15 m2/g, the radius of dominant plate pores rp = 80–90 Å, the calculated total pore volume ∑Vp = 0.661 cm3/g. Gyrolite texture changes upon introducing Na+ ions into its crystal structure: the specific surface area SBET diminishes to 27.24 m2/g, the radius of dominant cylindric pores rp = 60–70 Å, the calculated total pore volume #&8721Vp = 0.118 cm3/g.

14

Porosity of sol-gel silica glasses doped by ruthenium bipyridyl as measured by positron annihilation lifetime spectroscopy and nitrogen adsorption

Reisfeld R., Zigansky E., Jasińska B., Wodnicka K.

Optica Applicata

|

2005

|

Vol. 35, nr 4

677-689

EN

The porous structure of glasses incorporated by ruthenium tris bipyridyl chloride (further Rubpy) and adsorbed by Rubpy is studied by positron annihilation lifetime spectroscopy and liquid nitrogen adsorption method. The first method provides the radius of the pores in the range of 0.6-4 nm and their distribution. The second method provides the radius of the pores in the range of 1-150 nm, their total volumes, size distribution and specific surface area. In the first method both closed and opened pores can be seen when the measurements are made on bulk samples as in this work. When thin films are measured, one has to use a capping material to prevent backscattering. The dimension of the pores can be controlled by the catalyst used for sol-gel formation. When Rubpy is prepared by adding its salt to precursor solution catalyzed by HCl, the pore size increases because of stress exhibited by large molecules. The pore size decreases with adding of Rubpy in precursor solution, catalyzed by HF and HNO3. Glass doped by Rubpy is less sensitive to the type of catalyst, than undoped glasses. A comparative study was performed on undoped glasses prepared by the identical method. We shall discuss the similarities and differences of the two methods.

15

Badania właściwości uszczelniających kamienia cementowego metodą jądrowego rezonansu magnetycznego

Ciechanowska M., Zalewska J.

Prace Instytutu Nafty i Gazu

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2004

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nr 130

431--435

PL

W pracy przedstawiono wyniki badań wielkości przestrzeni porowej oraz rozkładu nasyceń wodą 19 próbek kamieni cementowych, o różnym składzie ilościowym i jakościowym, przy zastosowaniu metody jądrowego rezonansu magnetycznego. Biorąc pod uwagę możliwości migracji gazu w przestrzeni pozarurowej, także poprzez strukturę samego płaszcza cementowego, przedstawiono charakterystyki NMR tych próbek w aspekcie ich właściwości uszczelniających.

EN

Presented are results of lab-measurements of pore size distribution and water saturation for 19 cement samples with various chemical compositions. The measurement were carried out using the nuclear magnetic resonance method. Presented are NMR characteristic curries for those samples. Such a graphical presentation enable to evaluate the possibility gas migration through the cemented casing annulus (including gas migration through the cement matrix).

16

Waste fly ashes and their chemical modifications as cheap and effective adsorbents

Sarbak Z., Kramer-Wachowiak M.

Polish Journal of Chemical Technology

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2004

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Vol. 6, nr 4

51-59

EN

Fly ashes from the Power Plants were modified with the NaOH, HCl, EDTA solutions. On the basis of the X-ray diffraction, infrared spectroscopy, thermal analysis (DTA), and thermogravimetry (TG), it was found that the chemically modified fly ashes showed new crystalline structures. A study by scanning with the electron microscopy (SEM) allowed a detailed determination of the shape of the isles and agglomerates. The chemical treatment of the initial fly ashes resulted in a transformation of the bal-shaped agglomerations into different products characterised by a specific size and shape of the particles. The large surface area of the samples was confirmed by the tests with an adsorption of methylene blue (MB). The obtained samples were examined in the adsorptive removal of n-butylamine as a model air odorising compound. The adsorption abilities of the modified and unmodified fly ashes have been also tested in the removal of heavy metal ions such as zinc, cadmium, lead, chromium and nickel. Ions of these metals are often present in the industrial sewage. Fly ashes, modified with the NaOH solution showed the highest adsorption properties.

17

Saxas studies on porous materials.

Pająk L., Jarzębski A.B., Bierska B., Łągiewka E.

Inżynieria Materiałowa

|

1998

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R. XIX, nr 4

1191-1194

EN

The structure of most porous materials is quite complex. In the last two decades the characterisation of the structure of these materials made a milestone progress owing to the use of fractal geometry. At present it is generally accepted that the fractal models of pore structure describe the real structure better than the classical models which assume the existence of macro-, meso- and micropores of simple geometry. Pores are essential in materials applied as catalysts, filters, membranes, adsorbents. Thus the knowledge of the specific surface area, pore size and roughness of pore-solid interface is the prime importance. These parameters in the length scale 5-1000 angstrom can be estimated by the small-angle X-ray scattering (SAXS) method. The SAXS studies were performed on different porous silica materials, zirconia aerogels and metal foils electrodeposited in galvanostatic conditions. The fractal concept was applied to facilitate the interpretation of SAXS results.