Measurement of the specific surface area of fine powders. A comparison of the ‘gas-adsorption’ and ‘air-permeability’ methods

One of the main applications of ceria-based (CeO2) ceramics is the manufacturing of Intermediate Temperature Solid Oxide Fuel Cells electrolytes. In order to improve ionic conductivity and densification of these materials various powder synthesis routes have been studied. In this work powders with composition Ce0.8(SmGd)0.2O1.9 have been synthesized by coprecipitation and hydrothermal treatment. A concentrate of rare earths containing 90wt% of CeO2 and other containing 51% of Sm2O3 and 30% of Gd2O3, both prepared from monazite processing, were used as precursor materials. The powders were characterized by X-ray diffraction, scanning and transmission electron microscopy, agglomerate size distribution by laser scattering and specific surface area by gas adsorption. Ceramic sinterability was evaluated by dilatometry and density measurements by Archimedes method. High specific surface area powders (~100m2/g) and cubic fluorite structure were obtained after hydrothermal treatment around 200°C. Ceramic densification was improved when compared to the one prepared from powders calcined at 800°C.

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Optimization of compositions and technology of production of small-clinker floured cements using the most effective fillers

Bulletin of L N Gumilyov Eurasian National University Technical Science and Technology Series ◽

10.32523/2616-7263-2021-136-3-46-55 ◽

2021 ◽

Vol 136 (3) ◽

pp. 46-55

Author(s):

N.B. Sarsenbayev ◽

◽

B.K. Sarsenbayev ◽

Zh.T. Aimenov ◽

A.Zh. Aimenov ◽

...

Keyword(s):

Specific Surface ◽

Surface Area ◽

Crystalline Structure ◽

Specific Surface Area ◽

Chemical Properties ◽

Surface Layers ◽

Fine Powders ◽

Energy Demands ◽

Actual Evaluation ◽

Technology Of Production

Considering the physical chemistry of grinding it is worth quoting the grinding of mineral building material as “the change of physical-chemical properties of finely ground materials can not only be due to the reducing the particle sizes, at mechanical grinding significant changes of the crystalline structure of their surface layers (thickness 15-20 microns) take place, in many cases the technological properties of fine powders are not so much due to dispersability but are namely due to the structure rupture”, at that the energy costs for this are “significantly greater than for the exposal of surfaces with a clean cleavage”. The speed of heterogeneous chemical processes involving fine powders is determined primarily not by the magnitude of their specific surface area, as commonly is believed, but by the decrease of energy of activation as the result of crystalline structure rupture and amorphization. However, both specific surface area and energy demands to achieve are actual evaluation of the effectiveness of any material grinding at a particular unit. The main factor of the production process of cements of low water demand is the grinding, characterized by grindability.

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Influence of Acid Treatment on the Loading and Release Behavior of Halloysite with 2-Mercaptobenzothiazole

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2019.16616 ◽

2019 ◽

Vol 19 (11) ◽

pp. 7178-7184 ◽

Cited By ~ 2

Author(s):

Xuteng Xing ◽

Jihui Wang ◽

Qiushi Li ◽

Wenbin Hu

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Acid Treatment ◽

Gas Adsorption ◽

Treatment Time ◽

Halloysite Nanotubes ◽

Tubular Structure ◽

Internal Diameter ◽

Release Behavior

Halloysite nanotubes (HNTs) are natural clay minerals with a tubular structure. They have attracted considerable attention as a potential nanocontainer due to their abundance, biocompatibility and nontoxicity. In this study, HNTs were handled with H2SO4 at 70 °C. The morphology and structure of these acid-treated and original HNTs were investigated by scanning electron microscopy (SEM), energy dispersion spectrum (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), and their specific surface area was determined by automatic gas adsorption analyzer. The loading efficiency and release behavior of acid-treated HNTs for 2-Mercaptobenzothiazole (MBT) were investigated by UV-vis spectrophotometer. Results show that acid-treated HNTs retained their tubular structure, but their internal diameter expanded by 35–37 nm after 32 h of acid treatment. After 72 h of acid treatment, HNTs can be transferred into amorphous silica nanotubes. Moreover, the specific surface area of these HNTs samples initially increased with the increase in acid treatment time but then started to decrease after 32 h. The specific surface area of acid-treated HNTs at 32 h can reach 251.6 m2/g, which was much higher than that for untreated HNTs (55.3 m2/g). In addition, the loading capacity of acid-treated HNTs can reach 32.1% for HNTs-32, which is about three times higher than that of original HNTs. The acid treatment has slight effect on the release behavior.

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The whole-aperture pore-structure characteristics of marine-continental transitional shale facies of the Taiyuan and Shanxi Formations in the Qinshui Basin, North China

Interpretation ◽

10.1190/int-2018-0157.1 ◽

2019 ◽

Vol 7 (2) ◽

pp. T547-T563 ◽

Cited By ~ 2

Author(s):

Jiyuan Wang ◽

Shaobin Guo

Keyword(s):

High Pressure ◽

Specific Surface ◽

Pore Structure ◽

Surface Area ◽

Specific Surface Area ◽

Gas Adsorption ◽

Pore Morphology ◽

Qinshui Basin ◽

Mercury Intrusion ◽

Structure Characteristics

To systematically study the whole-aperture pore-structure characteristics of the marine-continental transitional shale facies in the Upper Palaeozoic Taiyuan and Shanxi Formations of the Qinshui Basin, we have collected a total of 11 samples for high-pressure mercury intrusion, low-pressure gas adsorption ([Formula: see text] and [Formula: see text]), nuclear magnetic resonance (NMR), and field-emission scanning electron microscopy with argon-ion polishing experiments to determine the pore morphology and distribution characteristics of shale samples in detail and to perform quantitative analyses. Then compared the pore-development characteristics of the Taiyuan Formation samples with those of the Shanxi Formation to determine which is preferable. The experimental results indicate that the shale samples of the Qinshui Basin mainly develop three types of pores: organic pores, intergranular pores, and microfractures. High-pressure mercury intrusion and gas-adsorption experiments indicate that the pore-size distributions exhibit multiple peaks. The samples contained varying proportions of macropores, mesopores, and micropores, among which the former two are dominant, accounting for approximately 85% of the total pore volume, whereas micropores account for only 15%. However, mesopores and micropores dominate the specific surface area; between them, the micropores are much more prevalent, accounting for more than 99% of the total specific surface area. Macropores contribute less than 1% of the specific surface area and therefore can be neglected. The pore morphology resembles the slit type parallel platy pores with a ballpoint pen structure. The NMR [Formula: see text] spectra have multiple-peak values. In addition, the large difference between the curved areas before and after centrifugation indicates that the samples contain a large proportion of mesopores and macropores, which is consistent with the results presented above. The results demonstrate that the development of pores in the Taiyuan Formation is better than that in the Shanxi Formation.

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Improve in CO2 and CH4 Adsorption Capacity on Carbon Microfibers Synthesized by Electrospinning of PAN

Fibers ◽

10.3390/fib7100081 ◽

2019 ◽

Vol 7 (10) ◽

pp. 81 ◽

Cited By ~ 3

Author(s):

Reyna Ojeda-López ◽

J. Marcos Esparza-Schulz ◽

Isaac J. Pérez-Hermosillo ◽

Armin Hernández-Gordillo ◽

Armando Domínguez-Ortiz

Keyword(s):

Specific Surface ◽

Adsorption Capacity ◽

Surface Area ◽

Specific Surface Area ◽

Gas Adsorption ◽

Morphological Structure ◽

Different Temperatures ◽

Ch4 Adsorption ◽

Stabilization Temperature ◽

Carbon Microfibers

Carbon microfibers (CMF) has been used as an adsorbent material for CO2 and CH4 capture. The gas adsorption capacity depends on the chemical and morphological structure of CMF. The CMF physicochemical properties change according to the applied stabilization and carbonization temperatures. With the aim of studying the effect of stabilization temperature on the structural properties of the carbon microfibers and their CO2 and CH4 adsorption capacity, four different stabilization temperatures (250, 270, 280, and 300 °C) were explored, maintaining a constant carbonization temperature (900 °C). In materials stabilized at 250 and 270 °C, the cyclization was incomplete, in that, the nitrile groups (triple-bond structure, e.g., C≡N) were not converted to a double-bond structure (e.g., C=N), to form a six-membered cyclic pyridine ring, as a consequence the material stabilized at 300 °C resulting in fragile microfibers; therefore, the most appropriate stabilization temperature was 280 °C. Finally, to corroborate that the specific surface area (microporosity) is not the determining factor that influences the adsorption capacity of the materials, carbonization of polyacrylonitrile microfibers (PANMFs) at five different temperatures (600, 700, 800, 900, and 1000 °C) is carried, maintaining a constant temperature of 280 °C for the stabilization process. As a result, the CMF chemical composition directly affects the CO2 and CH4 adsorption capacity, even more directly than the specific surface area. Thus, the chemical variety can be useful to develop carbon microfibers with a high adsorption capacity and selectivity in materials with a low specific surface area. The amount adsorbed at 25 °C and 1.0 bar oscillate between 2.0 and 2.9 mmol/g adsorbent for CO2 and between 0.8 and 2.0 mmol/g adsorbent for CH4, depending on the calcination treatment applicated; these values are comparable with other material adsorbents of greenhouse gases.

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Surface Analysis of Etched Molar Enamel by Gas Adsorption

Journal of Dental Research ◽

10.1177/154405910808700607 ◽

2008 ◽

Vol 87 (6) ◽

pp. 532-536 ◽

Cited By ~ 5

Author(s):

M.F. Orellana ◽

A.E. Nelson ◽

J.P.R. Carey ◽

G. Heo ◽

D.G Boychuk ◽

...

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Gas Adsorption ◽

Third Molar ◽

Dental Enamel ◽

Total Surface Area ◽

Gas Absorption ◽

Etch Pattern

Much research has been devoted to the study of etched enamel, since it is critical to bonding. Currently, there are no precise data regarding the etched-enamel specific surface area. The aim of this study was to characterize, by two different methods, the surface of human dental enamel in vitro after being etched. It was hypothesized that differences would be observed between specimens in terms of specific surface area and grade of etching. Sixteen third molar enamel samples were etched for 30 sec with 37% phosphoric acid prior to being viewed by SEM. Etched enamel surfaces were graded according to the Galil and Wright classification. The total surface area of etched samples was determined by the BET gas absorption method. A substantial variability in total surface area was observed between and among samples. A Pearson’s Correlation Coefficient showed a lack of relationship between etch pattern and total surface area.

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