Wyniki wyszukiwania - Biblioteka Nauki

1

Wyznaczanie powierzchni właściwej materiałów ziarnistych w aspekcie stosowania jej wielkości w wybranych procesach technologicznych

100%

Radomski P. , Jarosiński A.

Czasopismo Techniczne. Chemia

|

2010

|

tom R. 107, z. 1-Ch

267-276

PL

W artykule dokonano porównania wybranych metod wyznaczania powierzchni właściwej materiału ziarnistego. Zwrócono uwagę na zasady oznaczania powierzchni właściwej ze składu ziarnowego. Ustosunkowano się do wyboru metod określania powierzchni właściwej materiałów ziarnistych.

EN

Selected methods of specific surface area determination of the granular material were compared in this paper. Specific surface area was examined for different material granulations. The methods of specific surface area determination were analyzed and discussed for different grain size materials.

2

The Analysis of Friction Surfaces of the Needle Bearing Elements

100%

Nachimowicz J. , Korbut R.

Machine Dynamics Research

|

2010

|

tom Vol. 34, No. 1

92-100

EN

The article describes the changes in the surface area of contact two rolls with parallel axes: needles bearing and pin shaft. The study of factors affecting the surface area of contact elements cooperating: changing needles and shaft diameters, changing the values of Young modulus, Poisson ratio of materials, and changing load. Properties which are typical of deformed sections of friction surface have essential influence on the durability of the elements of friction couple. It is crucial to make the right choice of materials for friction elements and analysis of these elements. The conditions of transition were definite from the normal wear to pathological wear. It was done through determinate critical parameters such as: the value of clearance in connection, the intensity of wear in function of load.

3

The influence of silicate content on thermal stability of 2-line ferrihydrite and properties of its transformation products

100%

Pieczara G. , Rzepa G. , Gaweł A.

Geology, Geophysics and Environment

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2014

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tom Vol. 40, no. 1

160--161

EN

Naturally occurring ferrihydrite (Fe5HO8 • 4H2O) is a poorly ordered iron (oxyhydr)oxide mineral, with non-stoichiometric composition and not fully understood structure. Because of its unique chemical and physical properties, such as low crystallinity, high surface area and surface reactivity, ferrihydrite plays significant role in e.g. inorganic weathering processes, biochemical cycling of iron and as a sorbent in various near-surface environments. Ferrihydrite is a metastable phase and transforms with time into stable oxides: goethite and/or hematite, through dissolution-reprecipitation and dehydration-rearrangement mechanisms, respectively. Ferrihydrite structure provides numerous sorption sites and for this reason substantial amounts of admixtures are present in its chemical composition. The most common and well documented impurities include silicate, phosphate, arsenate, sulphate, calcium, aluminum and organic compounds. These ions affect ferrihydrite composition, surface molecular structure and sorption properties. Silicate, probably the most important impurity, causes decreasing crystallinity of this nanomineral, modifies magnetic ordering and solubility. Thus, natural ferrihydrite distinctly differ from synthetic pure analogue. As it was previously shown, the association of Si with ferrihydrite surface hindered thermal transformation to hematite. The implications of this observation for the understanding of Si-ferrihydrite stability in geochemical systems are obvious. The aim of this work was determining of the influence of the Si/Fe ratio in ferrihydrites on its thermal transformation processes and the properties of the products. Ferrihydrite samples having different Si/Fe molar ratios: 0.00, 0.05, 0.10, 0.20, 0.25, 0.50, 0.75, 1.00, and 1.50, were obtained by reaction of Fe2(SO4)3 with NaOH in the presence of Na2Si03 at pH 8.2. After four-day incubation, dialysis and freeze-drying, the precipitates were characterized using X-ray powder diffraction (XRD), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), Raman spectroscopy, and scanning electron microscopy (SEM). Then thermal analyses (DTA/DTG/TG) were performed. All of the ferrihydrites were heated from 30°C to 1000°C, at 10°C min-1 in flowing air, using hematite as inert material. After heating all the samples were again characterized by XRD and SEM-EDS methods. DTA curve of pure ferrihydrite shows typical dehydration endotherm at 160°C and. sharp exotherm at 350°C, attributed to hematite formation. Additional weak peaks at 550°C and 710°C were probably originated form decomposition of relic sulphate. The presence of Si in ferrihydrite appears to stabilize its structure and prevents conversion to hematite: the ferrihydrite-hematite transformation peak weakens and broadens and is shifted towards higher temperatures, up to ca. 900°C for high-Si materials. However, no simple linear relationship between silica content in ferrihydrite and the position of this peak has been found. X-ray diffraction patterns indicate that the main product of thermal transformation of all ferrihydrites is hematite (α-Fe2O3). For low-Si samples (Si/Fe < 0.20), a gradual broadening of 104, 214, 300, 110 hematite reflexes has been noticed, indicating the decrease of its crystallinity. On the other hand, for high-Si materials the broadening appears to be less distinct. Increasing Si/Fe molar ratio (≥ 0.10) in the initial material took an effect also in the appearance of a cristobalite-type oxide, the content of which increases drastically for the highest-Si samples. Additionally, the XRD pattern of the Si/Fe 0.10 sample reveals the presence of some spinel phase. Hematite originating from the heating of Si-free ferrihydrite forms quite large (up to 1 mm in size) isometric and prismatic crystals, often exhibiting pseudohexagonal shape. In contrast, the oxide particles become tenfold smaller even in the lowest-silicate material (Si/Fe = 0.05) and reveal pseudospheric morphology. In higher-silicate products (Si/Fe > 0.10) the crystallites are getting elongated and the elongation increases with increasing Si/Fe ratio. This preliminary study demonstrates that silicate content causes the retarding of ferrihydrite (thermal) transformation to hematite and affecting crystallinity of the latter. Even small Si admixture in the precursor reduces crystal size of the product. During roasting of low-Si ferrihydrites some Si probably enter the hematite structure, but higher-Si hematites cannot form and for this reason heating of high-Si ferrihydrites produces two-phase composition.

4

Flue gas desulfurization by mechanically and thermally activated sodium bicarbonate

100%

Walawska B. , Szymanek A. , Pajdak A. , Nowak M.

Polish Journal of Chemical Technology

|

2014

|

tom Vol. 16, nr 3

56--62

EN

This paper presents the results of study on structural parameters (particle size, surface area, pore volume) and the sorption ability of mechanically and thermally activated sodium bicarbonate. The sorption ability of the modified sorbent was evaluated by: partial and overall SO2 removal efficiency, conversion rate, normalized stoichiometric ratio (NSR). Sodium bicarbonate was mechanically activated by various grinding techniques, using three types of mills: fluid bed opposed jet mill, fine impact mill and electromagnetic mill, differing in grinding technology. Grounded sorbent was thermally activated, what caused a signifi cant development of surface area. During the studiem of SO2 sorption, a model gas with a temperature of 300°C, of composition: sulfur dioxide at a concentrationof 6292 mg/mn3 oxygen, carbon dioxide and nitrogen as a carrier gas, was used. The Best development of surface area and the highest SO2 removal efficiency was obtained for the sorbent treated by electromagnetic grinding, with simultaneous high conversion rate.

5

Prawna ochrona powierzchni ziemi i odpowiedzialność za szkody wyrządzone w powierzchni ziemi

100%

Górski M.

Auxiliary Sciences in Archaeology, Preservation of Relics and Environmental Engineering

|

2007

|

tom T. 3 spec. ed.

1-21

6

Flue Gas Desulfurization by Mechanically and Thermally Activated Sodium Bicarbonate

100%

Walawska B. , Szymanek A. , Pajdak A. , Nowak M.

Polish Journal of Chemical Technology

|

2014

|

tom 16

|

nr 3

56-62

EN

This paper presents the results of study on structural parameters (particle size, surface area, pore volume) and the sorption ability of mechanically and thermally activated sodium bicarbonate. The sorption ability of the modified sorbent was evaluated by: partial and overall SO2 removal efficiency, conversion rate, normalized stoichiometric ratio (NSR). Sodium bicarbonate was mechanically activated by various grinding techniques, using three types of mills: fluid bed opposed jet mill, fine impact mill and electromagnetic mill, differing in grinding technology. Grounded sorbent was thermally activated, what caused a significant development of surface area. During the studies of SO2 sorption, a model gas with a temperature of 300°C, of composition: sulfur dioxide at a concentration of 6292 mg/mn3, oxygen, carbon dioxide and nitrogen as a carrier gas, was used. The best development of surface area and the highest SO2 removal efficiency was obtained for the sorbent treated by electromagnetic grinding, with simultaneous high conversion rate.

7

Structural and textural characterisation of NiMo catalysts supported on various zeolites

88%

Sarbak Z. , Fabiś G. , Binkowski S.

Polish Journal of Chemical Technology

|

2007

|

tom 9

|

nr 1

27-32

EN

Structural and textural properties of nickel-molybdenum catalysts supported on four various type of zeolites of different chemical composition and porous structure have been studied by the methods of IR, XRD and the low-temperature sorption of nitrogen. The catalysts have been obtained by the two-stage impregnation of the supports with the solutions of nickel and molybdenum salts by the method of incipient wetness. The catalysts have been shown to preserve the structure characteristic of the appropriate zeolite supports.

8

Properties of active carbon with various particle shapes obtained in char-steam reaction Properties of active carbon with various particle shapes obtained in char-steam reaction

88%

Buczek B.

Chemical and Process Engineering

|

2012

|

tom 33

|

nr 3

335-344

EN

The porous structure of cylindrical and ring-shaped char material was developed by partial steam gasification. Micropore and mesopore structures of active carbons with various forms of burn-off were evaluated by nitrogen adsorption/desorption isotherms. Parameters of the Dubinin- Radushkevich equation were calculated as well as the micropore size distribution by the Horvath- Kawazoe method. The results of textural investigations showed that more uniform micropore structure and better mechanical properties were found for ring-shaped active carbons.

9

Characterization of Spent Bleaching Earth as an Adsorbent Material for Dye Removal

88%

Yulikasari A. , Nurhayati E. , Utama W. , Warmadewanthi I.

Journal of Ecological Engineering

|

2022

|

tom Vol. 23, nr 4

96--104

EN

Initial research has been carried out to determine the potential of SBE as an adsorbent material through chemical and surface area characterization. Several analyses were performed, including oil content, BET, SEM-EDS, XRD, FTIR, and adsorption capacity. The oil content of the SBE samples were 0.05–0.09%, well below the standard (3%) of hazardous material classification according to the Indonesian government regulation. The chemical composition of SBE, measured by EDS, was dominated by Si and Al elements. XRD analysis revealed two 2-theta diffraction peaks indicated the presence of crystalline SiO2 and Al2O3 phases. Additionally, the results of the FTIR test also showed the dominance of Si-O and Al-O-H functional groups. The SBE morphology, as observed in SEM image, exhibited irregular shape and porous surface covered by impurities. These results supported by the BET data which showed SBE surface area of 10.86 m2g-1 and a mesopore volume of 2.49 cm3 (STP)g-1. Batch adsorption study conducted using low and high range concentration of methylene blue produced a maximum adsorption capacity of 7.993 mg/g and 40.485 mg/g, respectively. The adsorption isotherm analysis showed that the adsorption mechanism was in accordance with the Langmuir isotherm model. Considering its chemical characteristic, SBE has met the criteria for adsorbent material. Nevertheless, the small surface area requires SBE to be activated prior to use.

10

The ratio of amount of haemoglobin to total surface area of erythrocytes in mammals

88%

Kostelecka-Myrcha A.

Acta Theriologica. Supplement

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2002

|

tom 47

|

nr 1

EN

The literature provides all the data needed to calculate the ratio between the amount of haemoglobin and the total surface area of erythrocytes in 54 species of mammals ranging in body mass from 2.5 g to more than 1000 kg. Analysis shows that the concentration of haemoglobin (Hb; g%) does not defend on the body mass ofthe mammals studied. The number of erythrocytes in 1 mm of blood (RBC; 10 x mm ) is significantly lower, and the diameter of these cells significantly higher, among larger mammals as opposed to smaller ones. The result is that the total surface area of erythrocytes in 1 mm of blood (TSAE; mm x mm ) is significantly lower among larger mammals, while the Hb/TSAE ratio (pg x ^m- ) is significantly greater. These results point to the smaller size of erythrocytes of smaller mammals permitting much greater numbers to exist, thereby producing a greater TSAE and smaller Hb/TSAE ratio. The greater total surface area of red blood cells per unit volume of blood in small mammals can in turn be presumed to allow for full saturation of haemoglobin by oxygen, even where the period of contact between erythrocytes and air in the lungs is shorter than in their larger counterparts.

11

Porównanie powierzchni właściwej i rozmiaru porów węgla metodami sorpcyjnymi w różnych temperaturach

75%

Pajdak A. , Skoczylas N.

Prace Instytutu Mechaniki Górotworu PAN

|

2014

|

tom Vol. 16, no. 3-4

85--92

PL

W artykule przedstawiono wyniki badań porozymetrycznych węgla kamiennego wyznaczonych metodą niskociśnieniowej adsorpcji gazowej. Pomiary przeprowadzono w kilku temperaturach, z zastosowaniem azotu (N2) w temperaturze 77 K oraz ditlenku węgla (CO2) w temperaturach 258 K, 273 K, 278 K i 288 K. Przy wykorzystaniu azotu jako adsorbatu określono objętość oraz powierzchnię właściwą mezoporów (BJH, BET). Ditlenek węgla posłużył do identyfi kacji powierzchni właściwej zgodnie z założeniami modelu adsorpcji jednowarstwowej (Langmuir) i wielowarstwowej (BET). Określono objętość, wielkość i rozkład mikroporów (HK) oraz charakterystyczną energię adsorpcji zgodnie z modelem DA.

EN

This paper presents the results of the porosimetric studies on coal appointed by low pressure gas adsorption. Measurements were carried out at several temperatures with gaseous adsorbate: nitrogen (N2) at 77 K and carbon dioxide (CO2) at temperatures of 258 K, 273 K, 278 K and 288 K. Nitrogen was used to determine volume and surface area of the mesopores (BJH, BET). Carbon dioxide was used to identify a specific surface area in accordance of monolayer (Langmuir) and multilayer (BET) adsorption models. The following parameters were identified: volume, size and distribution of micropores (HK) as well as characteristic energy of adsorption according to DA model.

12

Właściwości sorpcyjne wodorowęglanu sodu

75%

Walawska B. , Szymanek A. , Pajdak A. , Nowak M. , Hala B.

Chemik

|

2012

|

tom Vol. 66, nr 11

1169-1176

PL

Przedstawiono wyniki badań laboratoryjnych określających wpływ aktywacji mechanicznej i termicznej na właściwości sorpcyjne wodorowęglanu sodu. Stwierdzono, że najlepsze właściwości sorpcyjne, uzyskano w sorbencie mielonym po aktywacji w 250 st. C. Badania powierzchni właściwej potwierdziły makroporowaty charakter modyfikowanego wodorowęglanu sodu. Testy reaktywności potwierdziły jego znakomite właściwości sorpcyjne.

EN

The results of laboratory tests to determine the effect of mechanical and thermal activation on the sorption properties of sodium bicarbonate are reported. The best sorption properties were found in ground sorbent after activation at 250 st. C. The examination of the surface area confirmed the macroporous character of the modified sodium bicarbonate. Reactivity tests ascertained its excellent sorption properties.

13

Influences of operating parameters on dry ball mill performance

75%

Cayirli S.

Physicochemical Problems of Mineral Processing

|

2018

|

tom Vol. 54, iss. 3

751--762

EN

The paper is aimed to investigate the influence of operating parameters on dry fine grinding of calcite in a laboratory scale conventional ball mill. Within the context, the influence of operating parameters such as mill speed, ball filling ratio, ball size distribution, powder filling ratio, grinding aid dosage and grinding time were studied. The results of grinding tests were evaluated based on the product particle size (d50, d80) and surface area (m2/kg). As a result of this study, optimum grinding test conditions determined to be 70% of Nc, J=0.35 for ball filling ratio, 40 mm (10%), 32 mm (10%), 20 mm (40%), 12 mm (40%) for ball size distribution, fc=0.125 for powder filling ratio, 2000 g/Mg for grinding aid dosage and 60 min for grinding time. After determining optimum grinding conditions, the influence of grinding aid dosage on powder fluidity was determined. The use of 2000 g/Mg grinding aid dosage had a greater fluidizing effect compared to the other dosages and no aid condition (0 g/Mg). The influence of grinding aid on dry fine grinding of calcite was also examined by Fourier Transform Infrared Spectroscopy (FTIR). FTIR measurements indicated that grinding aid was adsorbed on the ground calcite particles surface.

14

Synthesis of inorganic oxide composites with the use of postgalvanic waste solutions of copper(II) sulfate

75%

Modrzejewska-Sikorska A. , Ciesielczyk F. , Jesionowski T.

Polish Journal of Chemical Technology

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2010

|

tom 12

|

nr 2

46-51

EN

The study was undertaken to obtain an oxide composite (inorganic colourful pigment) in the method based on the use of postgalvanic waste solution of copper(II) sulfate. The conditions of the process of precipitation of synthetic CuOSiO2 were optimised by checking the effect of the concentration and the volume ratio of the reagents and the temperature on the physico-chemical parameters of the final product. The oxide composite obtained in the optimum conditions was characterised by high refinement of particles and large specific surface area BET of 326 m2/g.

15

Badanie uziarnienia pigmentów ceramicznych

75%

Dziubak C. , Taźbierski P.

Laboratorium - Przegląd Ogólnopolski

|

2013

|

tom nr 3-4

50--54

PL

W technologiach ceramicznych uziarnienie substratów – surowców i półproduktów – ma istotne znaczenie dla jakości wytwarzanych tworzyw. Zwłaszcza pomiar wielkości ziaren poniżej 100 μm nabiera szczególnego znaczenia. W przypadku pigmentów ceramicznych od uziarnienia zależą ich parametry barwy, a w konsekwencji walory estetyczne i cechy użytkowe dekorowanych wyrobów.

EN

In the ceramic substrate technology the particle size of raw materials and semi-finished products is essential for the quality of the produced materials. Especially the measurement of particle size less than 100 microns is of particular importance. In the case of ceramic pigments, the color parameters and, consequently, aesthetic and functional characteristics of decorated products depend on their grain size.

16

Study on the possible existence of water on the Moon

75%

Robens E. , Halas S.

Geochronometria

|

2009

|

tom Vol. 33

23-31

EN

Aim of an extensive research project is an analysis of surface properties of Moon’s regolith covering and the assessment of the possible existence of usable water on the Moon. In the present paper a short historical survey on Moon’s exploration and recent and planned missions is given. Recent recognitions are discussed on the basis of origin and history of the Moon and the import of water from other celestial bodies. Characteristic data and chemical composition of the Moon’s surface are summarised with respect to possible water or ice preservation. Experimental investigations have been made on three typical lunar regolith powder samples from the Apollo 11, 12 and 16 missions. The experiments include spectroscopic and thermal analysis, density measurements and sorptometry. In the present paper we give a survey on measuring methods applied and discuss some results. The measurements confirm results of investigations made with less sensitive equipment shortly after the missions. With regard to water occurrence we found that the regolith cover of the Moon surface is rather hydrophobic and can hardly store water as adsorbed layers.

17

The size of selected human skull foramina in relation to skull capacity

75%

Wysocki J. , Reymond J. , Skarzynski H. , Wrobel B.

Folia Morphologica

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2006

|

tom 65

|

nr 4

301-308

EN

An anatomical study was undertaken in order to investigate whether the sizes of selected human skull foramina with significant venous compartments correlated significantly with skull capacity. A total of 100 macerated human skulls were examined to determine the diameter of the foramina and the skull capacity. Measurements of the surface area of the foramina were made using a computerised digital analysis system. Only the size of the hypoglossal canal and jugular foramen were found to correlate significantly with the capacity of the skull. This correlation, together with the considerable size of the hypoglossal canal, indicated its important role in the venous drainage of the brain. There was considerable centralisation of venous outflow from the brain, with 60% of the area of all venous foramina of the skull occupied by jugular foramina. Asymmetry between the right and left jugular foramina was identified, with an average ratio of 1.6 (ranging between 1 and 3.47). In the case of right-sided domination the correlation between the skull capacity and the size of both jugular foramina was negative (the larger the skull cavity, the less the asymmetry), while in the case of left-sided domination the correlation was positive. Perhaps the left-sided domination is less advantageous for the haemodynamics of blood outflow, as the left brachiocephalic vein is longer and is often compressed by the sternum and aortic arch.

18

Caracteristiques statistiques de la houle du vent etablies a l’aide de photos aeriennes

75%

Onoszko J. , Mikoteit A. , Wiejacha M.

Oceanologia

|

1978

|

tom 09

19

Metodyka wyznaczania pola powierzchni elementów złoża stanowiącego kamienny akumulator ciepła

75%

Mueller W. , Maćkowiak S. , Siatkowski I.

Journal of Research and Applications in Agricultural Engineering

|

2010

|

tom Vol. 55, nr 2

47-50

PL

Prawidłowa identyfikacja międzyfazowej powierzchni wymiany ciepła w kamiennym akumulatorze ma istotne znaczenie w procesie opisu zjawiska przepływu ciepła pomiędzy złożem a powietrzem. Transfer tej formy energii zachodzi w akumulatorze podczas każdej z faz pracy tego urządzenia. Zaproponowana przez autorów nowa metodyka określania pola powierzchni kamieni bazuje na podziale jego formy utworzonej przy użyciu pianki montażowej, a następnie na identyfikowaniu powierzchni cząstkowych. Proces ten przebiega z wykorzystaniem specjalnie do tego celu wytworzonego systemu informatycznego, w którym przetwarzaniu podlegają obrazy cyfrowe uzyskane w trakcie skanowania plastrów - obiektów podziału. Zaproponowane narzędzie badawcze zostało następnie wykorzystane do identyfikacji pola powierzchni elementów złoża kamiennego akumulatora, które stanowił tłuczeń granitowy.

EN

The correct identification of the interface of the heat exchange in a rock bed thermal storage is significant for the process of describing the heat flow between the bed and air. The transfer of this form of energy goes on during each of the phases of the device's work. New methodology of the identification of the surface area of the stones, suggested by the authors, bases on the division of its mould created using a foam concrete and then on the identification of the partial areas. The procedure is carried out by means of the specially created computer system in which the digital pictures, taken during the division objects scan, are processed. The suggested research device was then used to identify the surface areas of the elements of the rock storage's bed which was granite break stone.

20

Determination of orange volume and surface area using image processing technique

75%

Khojastehnazhand M. , Omid M. , Tabatabaeefar A.

International Agrophysics

|

2009

|

tom 23

|

nr 3

237-242