Effect of Catalyst Used in the Sol-Gel Process on the Microstructure and Adsorption/Desorption Performance of Silica Aerogels

2013 ◽  
Author(s):  
Kashif Nawaz ◽  
Shelly J. Schmidt ◽  
Anthony M. Jacobi
Keyword(s):  
Preparation Method ◽  
Sol Gel ◽  
Moisture Diffusivity ◽  
Silica Aerogels ◽  
Performance Parameters ◽  
Vapor Sorption ◽  
Dynamic Vapor Sorption ◽  
Sol Gel Process ◽  
Air Conditioning Systems ◽  
Adsorption Desorption

Silica aerogels are often deployed as solid desiccants in enthalpy wheels used for dehumidifying ventilation air in air-conditioning systems. These materials have good adsorption and desorption characteristics, but microstructure affects their moisture diffusivity. As the performance of desiccant systems depends on diffusivity, it is important to select a preparation method providing the desired aerogel microstructure for enhanced dehumidification performance. A study is described in which the structure of silica aerogels prepared by the Sol-Gel process is analyzed. The same precipitator (TMOS-Tetra methyl orthosilicate) and solvent (Methanol) are used to prepare all samples. It is found that density and microstructure are highly dependent on the catalyst used in the Sol-Gel process. Dynamic vapor sorption experiments are conducted to determine diffusivity. Microscopic images are analyzed to discern the structure and to relate it to corresponding adsorption or desorption performance parameters.

Texture Evaluation of Sol-Gel Derived Mesoporous Bioactive Glass

2013 ◽  
Vol 284-287 ◽  
pp. 230-234
Author(s):  
Yu Jen Chou ◽  
Chi Jen Shih ◽  
Shao Ju Shih
Keyword(s):  
Surface Area ◽  
Calcination Temperature ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Nitrogen Adsorption ◽  
Bioactive Glasses ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Adsorption Desorption

Recent years mesoporous bioactive glasses (MBGs) have become important biomaterials because of their high surface area and the superior bioactivity. Various studies have reported that when MBGs implanted in a human body, hydroxyl apatite layers, constituting the main inorganic components of human bones, will form on the MBG surfaces to increase the bioactivity. Therefore, MBGs have been widely applied in the fields of tissue regeneration and drug delivery. The sol-gel process has replaced the conventional glasses process for MBG synthesis because of the advantages of low contamination, chemical flexibility and lower calcination temperature. In the sol-gel process, several types of surfactants were mixed with MBG precursor solutions to generate micelle structures. Afterwards, these micelles decompose to form porous structures after calcination. Although calcination is significant for contamination, crystalline and surface area in MBG, to the best of the authors’ knowledge, only few systematic studies related to calcination were reported. This study correlated the calcination parameters and the microstructure of MBGs. Microstructure evaluation was characterized by transmission electron microscopy and nitrogen adsorption/desorption. The experimental results show that the surface area and the pore size of MBGs decreased with the increasing of the calcination temperature, and decreased dramatically at 800°C due to the formation of crystalline phases.

Adsorption–desorption kinetics of silica coated on textile fabrics by the sol–gel process

2019 ◽  
Vol 17 (2) ◽  
pp. 371-380 ◽  
Author(s):  
Mohamed El messoudi ◽  
Aicha Boukhriss ◽  
Omar Cherkaoui ◽  
M’hammed El kouali ◽  
Said Gmouh
Keyword(s):  
Sol Gel ◽  
Desorption Kinetics ◽  
Textile Fabrics ◽  
Sol Gel Process ◽  
Adsorption Desorption ◽  
Kinetics Of

Preparation of Silica Aerogels Monoliths from Hydrophobic Silica Gels and Pluronic10R5 via Sol–Gel Process

2020 ◽  
Vol 12 (2) ◽  
pp. 206-211
Author(s):  
Supattra Eangpayung ◽  
Supan Yodyingyong ◽  
Darapond Triampo
Keyword(s):  
Mass Loss ◽  
Propylene Oxide ◽  
Silica Aerogel ◽  
Sol Gel ◽  
Silica Aerogels ◽  
Silica Gels ◽  
High Porosity ◽  
Hydrophobic Silica ◽  
Sol Gel Process ◽  
Poly Propylene

Silica aerogel, the most common type of aerogels, comprised of 95% air in its structure which made the aerogel has a high surface area, high porosity, low density, and low thermal conductivity. Because of its structure and high porosity, one of its major weakness compared to other materials is being very brittle. This study aims at strengthening the connection points between silica nanoparticles using Pluronic10R5 (poly(propylene oxide)8–poly(ethylene oxide)22–poly(propylene oxide)8) where the Pluronic10R5 was used to reduce phase separation during the silica condensation reaction in the sol–gel process. Silica aerogel monoliths were prepared via a sol–gel process from hydrophobic silica gels and Pluronic10R5 with an ambient pressure drying (APD) process. Results from the compression test showed that the Pluronic10R5/silica aerogels have improved mechanical property by ten times that of unmodified silica aerogels. A thermogravimetric analysis (TGA) showed a mass loss at 300–400 °C that is attributed to the surface methyl group, while a mass loss at 200 °C refers to the loss of Pluronic10R5 which confirms the incorporation of Pluronic10R5 into the monolith. Moreover, infrared (IR) images revealed that the top surface temperature of Pluronic10R5/silica aerogels monolith is about 80 °C differs from the bottom heat source temperature of 160 °C.

Preparation and Characterization of Ultralow Density Silica Aerogels by Acetonitrile Supercritical Drying

2012 ◽  
Vol 519 ◽  
pp. 83-86 ◽  
Author(s):  
Guang Wu Liu ◽  
Xing Yuan Ni ◽  
Bin Zhou ◽  
Qiu Jie Yu
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Silica Aerogel ◽  
Sol Gel ◽  
Supercritical Drying ◽  
Silica Aerogels ◽  
High Specific Surface Area ◽  
Molar Ratio ◽  
Sol Gel Process

This paper deals with the synthesis of ultralow density silica aerogels using tetramethyl orthosilicate (TMOS) as the precursor via sol-gel process followed by supercritical drying using acetonitrile solvent extraction. Ultralow density silica aerogels with 6 mg/cc of density was made for the molar ratio by this method. The microstructure and morphology of the ultralow density silica aerogels was characterized by the specific surface area, SBET, SEM, and the pore size distribution techniques. The results show that the ultralow density silica aerogel has the high specific surface area of 812m2/g. Thermal conductivities at desired temperatures were analyzed by the transient plane heat source method. Thermal conductivity coefficients of silica aerogel monoliths changed from 0.024 to 0.043W/ (m K) as temperature increased to 400°C, revealed an excellent heat insulation effect during thermal process.

Synthesis of NaY Zeolite and their CO2 Adsorption Properties

2014 ◽  
Vol 1033-1034 ◽  
pp. 399-403
Author(s):  
Ren Juan Ma ◽  
Yong Quan Xu ◽  
Yu Min Liu ◽  
Rui Hong Zhao ◽  
Xiang Jing Zhang ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Gas Flow ◽  
Separation Efficiency ◽  
Sol Gel ◽  
Fixed Bed ◽  
Nay Zeolite ◽  
Sol Gel Process ◽  
Curve Method ◽  
Ft Ir ◽  
Adsorption Desorption

NaY zeolite was prepared by a simple sol-gel process. The prepared NaY was characterized by XRD,FT-IR,N2adsorption/desorption isotherms, and scanning electron microscope (SEM). The CO2dynamic adsorption/desorption performance of NaY was tested under atmospheric pressure using adsorption curve method in the fixed bed. The results demonstrate that NaY offeres high separation efficiency for CO2against N2. To further identify the most adsorption conditions, different adsorption temperatures and gas flow rates were investigated respectively. It is shown that NaY zeolite has the largest adsorption capacity of 88 mg/g adsorbent at 60°C,50ml/min, and the sample maintains still strong adsorption capacity and stable structure during 6 consecutive test cycles, which exhibits its stable adsorption/desorption behavior.

scholarly journals Preparation of FeBTC/silica aerogels by a co-sol-gel process for organic pollutant adsorption

2020 ◽  
Vol 6 (12) ◽  
pp. 1250g7
Author(s):  
Hongli Liu ◽  
Chengfeng Jiang ◽  
Hongyan Li ◽  
Zhong Chen
Keyword(s):  
Organic Pollutant ◽  
Sol Gel ◽  
Silica Aerogels ◽  
Sol Gel Process
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