scholarly journals Alteration of Physical and Chemical Properties of Clays Subjected to Pressure

2020 ◽  
Vol 20 (4) ◽  
pp. 304-316
Author(s):  
Valerii V. Seredin ◽  
◽  
Olga S. Siteva ◽  
Karine A. Alvanyan ◽  
Andrey V. Andrianov ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Specific Surface ◽  
Crystal Lattice ◽  
Size Distribution ◽  
Surface Area ◽  
Mineral Composition ◽  
Significant Influence ◽  
Sorption Activity ◽  
Particle Solution

Clays represent complex polymineral formations. The properties of clays, including sorption, are largely determined by the structure of their crystal lattice, mineral composition and particle size distribution, as well as by environmental conditions. The mineral composition of clays is represented by the energy on the surface of particles; and the particle size distribution is represented by the active surface area of particles. These two complex parameters mainly determine the sorption activity of clays. To change the sorption activity of clays, the latter are subjected to mechanical treatments, thermal modifications, and chemical activations with the use of chemical agents such as acids, alkalis, salts at various exposure times. Therefore, a study of patterns of changes in the structure and sorption properties of clays subjected to pressure was conducted. Experimental studies have shown that if kaolin is subjected to pressure, defects are formed in the structural pack of kaolinite mineral due to the removal of Al3+, Fe3+/2+, Mg2+, Si4+ ions from it. In this case, pressure has the maximum influence on the removal of Al3+ ions from the pack. As a result of the removal of ions, the formation of the defects deforms the crystal lattice of kaolinite. Data obtained through IR spectroscopy confirm the increase of defectiveness (irregularity) of the structure of kaolinite. It has been revealed that when kaolin is subjected to a pressure of 0–150 MPa, the sorption activity mostly depends on рН of the diffuse layer particle solution ZрН = 73 % and crystallite defectiveness degree ZМк = 24 %. The specific surface area of particles ZSsa = 1 % and kaolinite pack defectiveness Zс = 2 % do not have any significant influence on sorption. If kaolin is subjected to a pressure of 150–800 MPa, kaolin sorption activity mostly depends on kaolinite pack defectiveness Zс = 74 % and crystallite pack defectiveness ZМк = 19 %. The specific surface area of particles ZSsa = 3 % and рН of the diffuse layer particle solution ZрН =4 % do not have any significant influence on sorption.

scholarly journals Preparation and Characterization of NiO Nanoparticles by Anodic Arc Plasma Method

2009 ◽  
Vol 2009 ◽  
pp. 1-5 ◽  
Author(s):  
Hongxia Qiao ◽  
Zhiqiang Wei ◽  
Hua Yang ◽  
Lin Zhu ◽  
Xiaoyan Yan
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Specific Surface ◽  
Size Distribution ◽  
Surface Area ◽  
Specific Surface Area ◽  
Average Particle Size ◽  
Average Particle ◽  
Arc Plasma ◽  
Nio Nanoparticles

NiO nanoparticles with average particle size of 25 nm were successfully prepared by anodic arc plasma method. The composition, morphology, crystal microstructure, specific surface area, infrared spectra, and particle size distribution of product were analyzed by using X-ray diffraction (XRD), transmission electron microscopy (TEM) and the corresponding selected area electron diffraction (SAED), Fourier transform infrared (FTIR) spectrum, and Brunauer-Emmett-Teller (BET)N2adsorption. The experiment results show that the NiO nanoparticles are bcc structure with spherical shape and well dispersed, the particle size distribution ranging from 15 to 45 nm with the average particle size is about 25 nm, and the specific surface area is 33 m2/g. The infrared absorption band of NiO nanoparticles shows blue shifts compared with that of bulk NiO.

Influence and Mechanism Analysis of Particle Size Distribution of Multi-System Mineral Admixture on Concrete Performance

2021 ◽  
Vol 1036 ◽  
pp. 386-394
Author(s):  
Fu Xing Cheng ◽  
Yong Liu ◽  
Ji Xiao ◽  
Xiao Xu Deng ◽  
Hai Long Wang
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Particle Size Distribution ◽  
Specific Surface ◽  
Mechanical Activation ◽  
Size Distribution ◽  
Surface Area ◽  
Specific Surface Area ◽  
Mineral Admixture ◽  
Mechanism Analysis

To explore the effect of mechanical activation on the particle size distribution of the composite admixture a self-designed test jet mill is used. We have studied the effects of different specific surface areas of composite admixtures on the workability, mechanical properties and durability of concrete and combined X-ray diffraction (XRD) with scanning electron microscopy (SEM) to analyze the mechanism of concrete performance improvement. Results showed that, mechanical activation can significantly increase the content of particles below 3 um; appropriate increase in the specific surface area of composite admixture is conducive to improving the performance of concrete; As the specific surface area increases, the hydration activity of the composite admixture increases first and then tends to be stable; during the hydration process, more thin-plate Ca(OH)2 is converted into needle-shaped AFt, which improves the cement-based material and thereby improving the macro mechanical properties and durability.

scholarly journals Measurement of particle size distribution and specific surface area for crushed concrete aggregate fines

2017 ◽  
Vol 28 (3) ◽  
pp. 706-720 ◽  
Author(s):  
Rolands Cepuritis ◽  
Edward J. Garboczi ◽  
Chiara F. Ferraris ◽  
Stefan Jacobsen ◽  
Bjørn E. Sørensen
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Specific Surface ◽  
Size Distribution ◽  
Surface Area ◽  
Specific Surface Area ◽  
Concrete Aggregate ◽  
Crushed Concrete
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