Preparation of Porous Silica by Acid Dissociation of Thermally Activated Kaolinite

2011 ◽  
Vol 284-286 ◽  
pp. 1381-1384 ◽  
Author(s):  
Guang Hui Li ◽  
Wei Cheng ◽  
Tao Jiang ◽  
Na Sun ◽  
Ling Feng Ai
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Thermal Activation ◽  
Porous Silica ◽  
Acid Dissociation ◽  
Tem Analysis ◽  
Thermally Activated ◽  
High Resolution Tem ◽  
The Relationship

Preparation of porous silica from thermally activated kaolinite was investigated by using acid dissociation process, and the relationship between structural transformation and acid dissociation properties of aluminium were elucidated. AlVI transfers into AlV and AlIV when kaolinite changes into metakaolinite during thermal activation. AlV is dissoluble in acid, while AlVI, AlIV are difficult to be dissolved into acid, therefore, the coordinations of aluminium affect acid dissociation of alumina markedly. Mesoporous silica is made by acid dissociation alumina of metakaolinite, and the specific surface area of porous silica is determined by acid dissociation ratio of alumina. The dissociation ratio of aluminum is up to 97% when kaolinite is activated at 900°C for 15 min. Specific surface area of the porous silica material is 357 m2/g, the pore volume is 0.43 cc/g, and BJH pore diameter is 2.18 nm. The pore is found to be in the worm-like shape by high resolution TEM analysis.

Effect of ACF Properties on the Electric Adsorption Performance of the ACF Electrode

2012 ◽  
Vol 209-211 ◽  
pp. 1990-1994 ◽  
Author(s):  
Qin Zhang ◽  
Zhao Hui Zhang ◽  
Liang Wang ◽  
Zi Long Zhang ◽  
Xing Fei Guo
Keyword(s):  
Activated Carbon ◽  
Carbon Fiber ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Activated Carbon Fiber ◽  
Adsorption Performance ◽  
Carbon Fiber Cloth ◽  
Activated Carbon Fiber Cloth ◽  
The Relationship

The properties of four different activated carbon fiber cloth (ACF), such as specific surface area, pore volumes and pore size distribution, were evaluated. The relationship between ACF properties and its electrosorption performance was analyzed. The experimental results show that pore structure has more influence on the performance of ACF electrode than that of specific surface area for ACF material. More abundant mesopores and shallower pore channels for ACF is favorable to improve the specific capacitance and electrosorption capacity of ions.

Influence of Surface Area on the Flowability Behaviour of Self-Flow Refractory Castables

2010 ◽  
Vol 636-637 ◽  
pp. 124-129 ◽  
Author(s):  
D.G. Pinto ◽  
Abílio P. Silva ◽  
A.M. Segadaes ◽  
T.C. Devezas
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Raw Materials ◽  
High Hardness ◽  
Size Composition ◽  
High Melting Point ◽  
Refractory Castables ◽  
Materials Used ◽  
The Relationship

Alumina, with high melting point (2050°C), high hardness and mechanical strength, and excellent abrasion resistance, is one of the most common raw materials used in self-flow refractory castables (SFRC) for monolithic linings and is commercially available in various fine to coarse size classes. However, the performance of the refractory lining depends not only on the properties of its ingredients but also on its easy installation (good flowability). The aim of this work was to evaluate the relationship between the flowability index (FI) of fresh castable and the specific surface area (SSA) of its particles, which is mostly determined by the finer particles content. The results obtained showed that, by controlling the proportion between matrix and aggregate, it is possible to control the SSA of the refractory castable and find a mathematical relationship between the specific surface area and the minimum flowability index required to obtain a self-flow refractory castable. It is, thus, possible to optimize the refractory castable size composition and obtain an estimate for FI as a function of SSA. Using a minimum 45 wt.% matrix content in the castable mixture, a SSA value above 2.215 m2/g is obtained, which leads to FI ≥ 80%, the recommended value for self-flow.

Annealing of mesoporous silica loaded with silver nanoparticles within its pores from isothermal sorption

1998 ◽  
Vol 13 (10) ◽  
pp. 2888-2895 ◽  
Author(s):  
Weiping Cai ◽  
Lide Zhang ◽  
Huicai Zhong ◽  
Guoliang He
Keyword(s):  
Mesoporous Silica ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Ag Nanoparticles ◽  
Porous Silica ◽  
Pore Wall ◽  
Ag Particles ◽  
Real Value ◽  
And Diffusion

Influences of annealing on the structure of mesoporous silica loaded with silver (Ag) nanoparticles, and on the coarsening of Ag particles within pores of the host were investigated from isothermal sorption. Doping a small amount of Ag nanoparticles into pores of silica and subsequent annealing decreases the measured values of specific surface area and pore volume of porous silica significantly. This is attributed to the presence and coarsening of Ag particles within pores or channels between pores, which result in more and more isolated and unmeasured free spaces. The measured value of a specific surface area for the doped samples cannot represent the real value, which is, in fact, unable to be measured directly. During additional annealing, Ag particles within silica coarsen mainly according to the mechanism of formation of Ag adatoms on pore wall and diffusion of the adatoms along with pore walls. Only the larger particles located in the larger pores can continuously grow. The smaller particles and those located in the channels or pores with smaller dimension will disappear. The activation energy of the ripening process was estimated to be about 0.60 eV, and the migration barrier of Ag adatom on the pore wall of silica is about 0.10 eV.

scholarly journals The Brandon mathematical model describing the effect of calcination and reduction parameters on specific surface area of ex-ADU UO₂ powders

2016 ◽  
Vol 6 (3) ◽  
pp. 54-59
Author(s):  
Trong Hung Nguyen ◽  
Ba Thuan Le
Keyword(s):  
Mathematical Model ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Uranyl Carbonate ◽  
Proposed Model ◽  
And Control ◽  
The Relationship ◽  
Fabrication Parameters ◽  
Good Agreement

The report “Brandon mathematical model describing the effect of calcination and reduction parameters on specific surface area of UO2 powders” [14] has built up a mathematical model describing the effect of the fabrication parameters on SSA (Specific Surface Area) of ex-AUC (Ammonium Uranyl Carbonate) UO2 powders. In the paper, the Brandon mathematical model that describe the relationship between the essential fabrication parameters [reduction temperature (TR), calcination temperature (TC), calcination time (tC) and reduction time (tR)] and SSA of the obtained ex-ADU (Ammonium Di-Uranate) UO2 powder product has established. The proposed model was tested with Wilcoxon’s rank sum test, showing a good agreement with the experimental parameters. The proposed model can be used to predict and control the SSA of ex-ADU UO2 powders

Finding the Specific Surface Area of an Organomineral Sorbent Produced by Electroplasma Treatment of Coal Flotation Waste

2021 ◽  
Vol 887 ◽  
pp. 603-609
Author(s):  
A.S. Kondratenko ◽  
S.L. Buyantuev ◽  
S.Yu. Shishulkin
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Thermal Activation ◽  
Thermal Destruction ◽  
Adsorption Model ◽  
Langmuir Adsorption ◽  
Coal Flotation ◽  
Solid Adsorbent ◽  
Before And After

This paper dwells upon finding the specific surface area of cake, a coal enrichment waste, exposed to electroplasma treatment; the goal is to make an organomineral porous material to be used as a sorbent for wastewater treatment. The research team used a monomolecular Langmuir adsorption model and surface tension of the surfactants before and after adsorption at the interface of solution and solid adsorbent. Another process considered herein was thermal activation of substances in the electroplasmic reactor for making organomineral porous materials from coal cakes. The paper presents the resulting specific surfaces area of the organomineral sorbent thus produced. Thus, the waste of flotation, i.e. coal cake, is fundamentally suitable for making porous substances by thermal destruction in an electroplasma reactor.

scholarly journals Glass fiber supports modified by layers of silica and carbon nanofibers

2017 ◽  
Vol 4 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Maxim V. Popov ◽  
Sergey V. Zazhigalov ◽  
Tatyana V. Larina ◽  
Svetlana V. Cherepanova ◽  
Alexander G. Bannov ◽  
...  
Keyword(s):  
Specific Surface ◽  
Glass Fiber ◽  
Surface Area ◽  
Carbon Nanofibers ◽  
Specific Surface Area ◽  
Ambient Pressure ◽  
Porous Silica ◽  
Layered Composite ◽  
Fiber Fabric

AbstractThe new multi-layered composite was manufactured by deposition of the carbon nanofibers (CNF) at the surface of the glass-fiber fabric, which is pre-modified by application of additional external layers of NiO and porous silica. Carbonization of synthesized catalytic template was performed at 450 °C in propanebutane media at ambient pressure. CNF was deposited in amount of ~130% of initial template mass or 65 g per g of nickel, the specific surface area of the material is ~100 m

Facile Synthesis of CeO2/SnO2 N-N Heterostructure

2019 ◽  
Vol 891 ◽  
pp. 200-205 ◽  
Author(s):  
Pimpan Leangtanom ◽  
Nattharinee Charoenrat ◽  
Sukon Phanichphant ◽  
Viruntachar Kruefu
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Average Particle Size ◽  
High Specific Surface Area ◽  
Element Composition ◽  
Precipitation Method ◽  
Average Particle ◽  
Tem Analysis ◽  
Co Precipitation

Cerium oxide and tin oxide nanocomposites (CeO2-SnO2 NCs) were successfully synthesized via a simple co-precipitation method. The structure and properties of the synthesized materials were characterized using several X-ray and electron-based techniques including XRD, FE-SEM, TEM, EDS and BET to unravel the structure, morphology, element composition and specific surface area. The XRD and BET results showed that the NCs have the characteristic crystalline structures of SnO2 and CeO2-SnO2 NCs, and high specific surface area (66.45 and 86.29 m2/g), respectively. Amorphous phase of CeO2 and SnO2 were not found in XRD patterns. EDS analysis confirms the absence of all element composition and the FE-SEM and TEM analysis observed as particles having the clear spherical morphologies with the average particle size of of SnO2 and CeO2-SnO2 NCs was about 13 and 10 nm, respectively.

scholarly journals Texture and Microstructure of Thermally-Treated Acid-Leached Kaolinitic Clays

2009 ◽  
Vol 27 (7) ◽  
pp. 671-684 ◽  
Author(s):  
Mervat Hassan ◽  
Hassan El-Shall
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Amorphous Silica ◽  
Pore Volume ◽  
Condensation Reaction ◽  
Broad Band ◽  
Porous Silica ◽  
Total Pore Volume ◽  
Calcination Time

Natural and modified kaolinitic clays were investigated by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM and EDS) and N2 adsorption techniques. Disordered, poorly crystalline kaolinite, containing some quartz and very little mica, was calcined at different temperatures and different times and then leached with 25 wt% sulphuric acid for 1 h at 98 °C. Calcination led to a reduction in both the specific surface area and the total pore volume due to dehydroxylation of kaolinite to meta-kaolinite (MK). However, subsequent leaching of the meta-kaolinite had a striking effect on the microporosity of the modified products. Thus, heating at 886 °C at 2 h (to yield MK2 886°C) and subsequent leaching for 1 h produced porous silica with a specific surface area of 233 m2/g and a total pore volume of 0.22 m2/g. The increase in the specific surface area (SBET) of the porous silica was due to the formation of micropores of 1.2–1.8 nm diameter and mesopores of 4.0–5.5 nm diameter inside the porous structure. The variation in the specific surface area and the porosity of acid-leached meta-kaolinite was found to depend not only on the calcination temperatures but also on the calcination time. Increasing the calcination time up to 6 h had a negative effect on the microporosity, attributed to a condensation reaction. The characteristics of the hysteresis loops in the corresponding adsorption/desorption isotherms indicated the formation of mainly slit-shaped pores. A broad band at 2θ = 21.8° in the XRD patterns of the modified samples was assigned to amorphous silica. The infrared spectra of acid-leached meta-kaolinite showed bands at 1095 cm−1 and 795–802 cm−1, respectively, which could be assigned to a three-dimensional amorphous silica phase.

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