Experimental Investigation of the Matrix Pore Size Distribution and Inner Surface Fractal Dimension of Different-Structure High Rank Coals

2021 ◽  
Vol 21 (1) ◽  
pp. 529-537
Author(s):  
Rui Wang ◽  
Guoqing Li ◽  
Shanshan Liu
Keyword(s):  
Size Distribution ◽  
Fractal Dimensions ◽  
Nitrogen Adsorption ◽  
Full Scale ◽  
High Rank ◽  
Shanxi Province ◽  
Coal Matrix ◽  
Surface Fractal ◽  
Inner Surface ◽  
Scale Matrix

To investigate the nanopore characteristics of different-structure high-rank coal matrices, four samples were collected from the Zhaozhuang Mine, a typical mine highly prone to coal and gas outbursts in Shanxi Province, China, and the nanopore size distribution was measured using a lowtemperature nitrogen adsorption method for these four samples. Based on the nitrogen adsorption isotherms, the inner surface fractal dimensions of micropores, meso- and macropores, and full-scale matrix pores were estimated using a Frenkel–Halsey–Hill (FFH) fractal model, and the relationships between the fractal dimensions and pore parameters were discussed. The inner surface of the high-rank coal matrix is heterogeneous. The inner surface fractal dimensions of micropores (D1) and full-scale matrix pores (DT) can be arranged in a descending sequence for the differentstructure coals: mylonitized coal > granulated coal > cataclastic coal > intact coal, while the inner surface fractal dimensions of meso- and macropores (D2) are in an ascending sequence. With the increasing deformation degree of coals, some macropores and mesopores are transformed into smaller pores, such as micropores; the total pore volume (PV) and total specific surface area (SSA) increase; the SSA percentage and PV percentage of meso- and micropores increase; and those of macropores decrease. The average pore width (APW) is positively correlated with D2 and negatively correlated with D1 and DT. The tectonic deformation enhances the irregularity of micropores and the heterogeneity of the whole coal matrix pores and decreases the inner surface roughness of meso- and macropores.

Fractal Characteristics and Its Controlling Factors of Nanopore of Coal from Shanxi Province, North China

2021 ◽  
Vol 21 (1) ◽  
pp. 727-740
Author(s):  
Zhi Xu ◽  
Ming Li ◽  
Yu Xu ◽  
Luwei Sun
Keyword(s):  
Fractal Dimension ◽  
Coalbed Methane ◽  
Correlation Coefficients ◽  
Fractal Dimensions ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Fractal Model ◽  
Shanxi Province ◽  
Fractal Characteristics ◽  
Permian Coal

Much attention has been recently paid to the Carboniferous-Permian coal-bearing strata in Shanxi Province, now the largest producing coalbed methane field in China. In this study, a comprehensive approach of mercury injection, low-temperature liquid nitrogen adsorption, and permeability experiments was adopted to investigate the structure and fractal characteristics of nanopores in the Carboniferous-Permian coal (with 0.77%˜3.04% Ro,ran). Based on the fractal model, two fractal dimensions D1 and D2 corresponding to diffusion pore (<65 nm) and seepage pore (pore size ≥65 nm), respectively, were calculated, and the relationships between the fractal dimensions with the pore structure parameters and permeability are discussed here. The results indicate that the studied coal samples have good fractal characteristics and that the calculated linear correlation coefficients are higher than 0.80. The fractal dimension D1 of the diffusion pores ranges from 2.3777 to 2.4624, with an average of 2.4173, while the fractal dimension D2 of the seepage pores is between 2.5844 and 2.6256, with an average of 2.5990. The fractal dimensions D1 of the diffusion pores increases with an increase in the BET specific surface area, vitrinite content, and Ro,ran while it decreases with an increase in the permeability, and has a weak correlation with the total pore volume. The correlation coefficients R2 for the fractal dimension D2 of the seepage pores, pore parameters, permeability, and maceral composition ranges from 0.0357 to 0.2551. These results indicate that uncertain relationships exist among these parameters.

scholarly journals Spectral and Texture Properties of Hydrophobic Aerogel Powders Obtained from Room Temperature Drying

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1796
Author(s):  
Dimitar Shandurkov ◽  
Petar Ignatov ◽  
Ivanka Spassova ◽  
Stoyan Gutzov
Keyword(s):  
Room Temperature ◽  
Fractal Dimensions ◽  
Nitrogen Adsorption ◽  
Attenuated Total Reflectance ◽  
Ir Absorption ◽  
Solvent Exchange ◽  
Texture Properties ◽  
Surface Fractal ◽  
Desorption Isotherms ◽  
Adsorption Desorption

Attenuated Total Reflectance Infrared (ATR-IR) spectroscopy and texture measurements based on nitrogen adsorption-desorption isotherms are combined to characterize silica aerogel granules with different degrees of hydrophobicity. The aerogels were prepared from tetraethoxysilane via a room temperature hydrolysis-gelation process, solvent exchange, hydrophobization, and drying at subcritical conditions. The dependencies between the texture properties, pore architectures, surface fractal dimensions, and degree of hydrophobicity of the samples are extracted from the ATR-IR spectra and the adsorption-desorption isotherms. The IR absorption in the region of the Si-O-Si and Si-OH vibrations is used for a description of the structural and chemical changes in aerogel powders connected with their surface hydrophobization. The Frenkel–Halsey–Hill (FHH) theory is applied to determine the surface fractal dimension of the powder species.

Surface Fractals and Wetting Properties of Porous Anodes Strengthened by Ni3Al for Molten Carbonate Fuel Cell

2007 ◽  
Vol 26-28 ◽  
pp. 861-864
Author(s):  
Yun Sung Kim ◽  
Kil Ho Moon ◽  
Jun Heok Lim
Keyword(s):  
Mercury Porosimetry ◽  
Capillary Rise ◽  
Fractal Dimensions ◽  
Nitrogen Adsorption ◽  
Contact Angles ◽  
Molten Carbonate Fuel Cell ◽  
Molten Carbonate ◽  
Adsorption Method ◽  
Capillary Rise Method ◽  
Surface Fractal

The contact angles of pure Ni, Ni/7wt%Ni3Al, Ni/5wt%Ni3Al/ 5wt%Cr and Ni/10wt%Cr anodes for the MCFC were measured by means of the capillary rise method in 62mol%Li2CO3+ 38mol%K2CO3 and 52mol%Li2CO3+ 48mol% Na2CO3 electrolyte and at different atmosphere. Also surface fractal dimension (Ds), which could characterize pore structure of the anodes, was calculated from experimental data obtained by mercury porosimetry and nitrogen adsorption method. The surface fractal dimensions of the anode were in range from 2.75 to 2.81, because porosities of the anodes for MCFC were controlled regularly to about 62% during sintering. It was investigated from wetting-in experiment by capillary-rise method that the contact angles between the anodes and the carbonate electrolytes were relatively decreased at CO2 atmosphere rather than air atmosphere and the angles were also decreased in the 62mol%Li2CO3+38mol%K2CO3 electrolyte rather than that measured and in the 52mol%Li2CO3+48mol% Na2CO3 electrolyte.

scholarly journals Ball-milling effect on Indonesian natural bentonite for manganese removal from acid mine drainage

2018 ◽  
Vol 156 ◽  
pp. 03046 ◽  
Author(s):  
Widyawanto Prastistho ◽  
Winarto Kurniawan ◽  
Hirofumi Hinode
Keyword(s):  
Particle Size ◽  
Acid Mine Drainage ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Mine Drainage ◽  
Nitrogen Adsorption ◽  
Exchange Capacity ◽  
Manganese Removal ◽  
Acid Mine ◽  
Adsorption Desorption

The influences of mechanical milling on Indonesian Natural Bentonite (INB) characteristics and manganese (Mn) removal from acid mine drainage (AMD) were investigated. The INB characteristics were observed by scanning electron microscope (SEM), X-ray diffraction (XRD), nitrogen adsorption-desorption for specific surface area (SSA) and microporosity measurement, cation exchange capacity (CEC) and particle size distribution (PSD) analyzer. Four minutes milling with frequency 20 Hz on INB caused morphological change which showed more crumbled and destructed particle, lost the (001) peak but still retained the (100) peak that indicated delamination of montmorillonite mineral without breaking the tetrahedral-octahedral-tetrahedral (T-O-T) structure, rose the CEC from 28.49 meq/100g to 35.51 meq/100g, increase in the SSA from 60.63 m2/g to 104.88 m2/g, significant increase in microporosity which described in the t plots and decrease in the mean particle size distribution peak from 49.28 μm to 38.84 μm. The effect of contact time and effect of adsorbent dosage on Mn sorption was studied. Both unmilled and milled samples reached equilibrium at 24 hours and the pH rose from 4 to 7 in first 30 minutes. The Mn removal percentage increased significantly after milling. Using Langmuir isotherm, the maximum adsorbed metals (qmax) also increased from 0.570 to 4.219 mg/g.

scholarly journals Structure and Strength of Artificial Soils Containing Monomineral Clay Fractions

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4688
Author(s):  
Grzegorz Jozefaciuk ◽  
Kamil Skic ◽  
Agnieszka Adamczuk ◽  
Patrycja Boguta ◽  
Krzysztof Lamorski
Keyword(s):  
Fine Particles ◽  
Structural Parameters ◽  
Fractal Dimensions ◽  
Soil Strength ◽  
Uniaxial Compression Test ◽  
Mineral Particle ◽  
Type Curve ◽  
Surface Fractal ◽  
First Time

Structure and strength are responsible for soil physical properties. This paper determines in a uniaxial compression test the strength of artificial soils containing different proportions of various clay-size minerals (cementing agents) and silt-size feldspar/quartz (skeletal particles). A novel empirical model relating the maximum stress and the Young’s modulus to the mineral content basing on the Langmuir-type curve was proposed. By using mercury intrusion porosimetry (MIP), bulk density (BD), and scanning electron microscopy (SEM), structural parameters influencing the strength of the soils were estimated and related to mechanical parameters. Size and shape of particles are considered as primary factors responsible for soil strength. In our experiments, the soil strength depended primarily on the location of fine particles in respect to silt grains and then, on a mineral particle size. The surface fractal dimension of mineral particles played a role of a shape parameter governing soil strength. Soils containing minerals of higher surface fractal dimensions (rougher surfaces) were more mechanically resistant. The two latter findings appear to be recognized herein for the first time.

scholarly journals ZnTiO3 ceramic nanopowder microstructure changes during compaction

2013 ◽  
Vol 45 (2) ◽  
pp. 209-221
Author(s):  
N. Labus ◽  
J. Krstic ◽  
S. Markovic ◽  
D. Vasiljevic-Radovic ◽  
M.V. Nikolic ◽  
...  
Keyword(s):  
Particle Size ◽  
Pore Size ◽  
Size Distribution ◽  
Mercury Porosimetry ◽  
Critical Diameter ◽  
Nitrogen Adsorption ◽  
Powder Particle Size ◽  
Scanning Electron Micrographs ◽  
Force Microscopy ◽  
Scanning Electron

ZnTiO3 nanopowder as a constitutive component in compact production was primarily characterized. Scanning electron micrographs of as received powder were recorded. Mercury porosimetry and nitrogen adsorption were also performed on loose powder. Particle size distribution in a water powder suspension was determined with a laser particle size analyser. Compaction was performed on different pressures in a range from 100 to 400 MPa using the uniaxial double sided compaction technique without binder and lubricant. Micrographs of compacted specimens were obtained using scanning electron microscopy and atomic force microscopy. Pore size distribution was also determined by mercury porosimetry and nitrogen adsorption. Results revealed that with increasing pressure during compaction interagglomerate pores diminish in size until they reach some critical diameter related to the intra-agglomerate pore size.

scholarly journals Fractal Characterization of Nanopore Structure in Shale, Tight Sandstone and Mudstone from the Ordos Basin of China Using Nitrogen Adsorption

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 583 ◽  
Author(s):  
Xiaohong Li ◽  
Zhiyong Gao ◽  
Siyi Fang ◽  
Chao Ren ◽  
Kun Yang ◽  
...  
Keyword(s):  
Pore Structure ◽  
Pressure Range ◽  
Ordos Basin ◽  
Fractal Dimensions ◽  
Nitrogen Adsorption ◽  
Relative Pressure ◽  
Tight Sandstone ◽  
Porosity And Permeability ◽  
The Ordos Basin ◽  
Nanopore Structure

The characteristics of the nanopore structure in shale, tight sandstone and mudstone from the Ordos Basin of China were investigated by X-ray diffraction (XRD) analysis, porosity and permeability tests and low-pressure nitrogen adsorption experiments. Fractal dimensions D1 and D2 were determined from the low relative pressure range (0 < P/P0 < 0.4) and the high relative pressure range (0.4 < P/P0 < 1) of nitrogen adsorption data, respectively, using the Frenkel–Halsey–Hill (FHH) model. Relationships between pore structure parameters, mineral compositions and fractal dimensions were investigated. According to the International Union of Pure and Applied Chemistry (IUPAC) isotherm classification standard, the morphologies of the nitrogen adsorption curves of these 14 samples belong to the H2 and H3 types. Relationships among average pore diameter, Brunner-Emmet-Teller (BET) specific surface area, pore volume, porosity and permeability have been discussed. The heterogeneities of shale nanopore structures were verified, and nanopore size mainly concentrates under 30 nm. The average fractal dimension D1 of all the samples is 2.1187, varying from 1.1755 to 2.6122, and the average fractal dimension D2 is 2.4645, with the range from 2.2144 to 2.7362. Compared with D1, D2 has stronger relationships with pore structure parameters, and can be used for analyzing pore structure characteristics.

scholarly journals Comparison of Nitrogen Adsorption and Mercury Penetration Results: II. Pore size Distributions Calculated from Type IV Isotherm Data

1988 ◽  
Vol 5 (3) ◽  
pp. 168-190 ◽  
Author(s):  
Bruce D. Adkins ◽  
Burtron H. Davis
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Nitrogen Adsorption ◽  
Type Iv ◽  
Pore Size Distributions ◽  
Nitrogen Desorption ◽  
The Difference ◽  
Penetration Data ◽  
Packed Sphere

The pore distributions calculated from nitrogen desorption and from mercury penetration data are similar for the four materials utilized in this study. While there are small differences in the distributions calculated using different models (Cohan. Foster or Broekhoff-deBoer) with nitrogen adsorption or desorption isotherm data, all three show reasonable agreement with distributions calculated from mercury penetration data. Frequently practical catalysts have such a broad pore size distribution that neither method alone is adequate to measure the total pore size range. The present results suggest a direct comparison, without recourse to a scaling factor, is appropriate when comparing results from the two methods even though the pore size distribution maximum may vary by at least 50% depending upon the model chosen for the calculation. Better agreement may be obtained between the two experimental techniques by adjusting either the nitrogen adsorption data using a packed sphere model or the mercury penetration data by an earlier reported correction ratio. The difference between the two methods becomes less than 20% when a correction procedure is used; however, further studies are needed to define the range of material shaped that these procedures are applicable to.

Fractal Dimension of Floc Growth in Micro-Coagulation Stage II: Some Normal Influencing Factors

2011 ◽  
Vol 243-249 ◽  
pp. 4827-4830
Author(s):  
Hao Yu Li ◽  
Jun Nan ◽  
Wei Peng He
Keyword(s):  
Particle Size ◽  
Fractal Dimension ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Influencing Factors ◽  
Aluminum Chloride ◽  
Fractal Dimensions ◽  
Coagulation Time ◽  
On Line ◽  
Line Detector

The coagulation experiment, with Kaolin as objects, aluminum chloride (PAC) as coagulant and hydrated MnO2 as coagulant aid, were accomplished under different conditions. In the experiment, the particle size distribution and turbidity in water were detected by on-line detector. The results show that increase PAC dosage, original turbidity, hydrated MnO2 dosage and coagulation time will make the fractal dimensions of floc growth in micro-coagulation stage increase. The fractal dimensions of floc growth in micro-coagulation stage increasing means more particle size <5µm flocs are removed. Hydrated MnO2 can strengthen micro-coagulation.

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