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

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.

scholarly journals Crystalline ZnO Photocatalysts Prepared at Ambient Temperature: Influence of Morphology on p-Nitrophenol Degradation in Water

Catalysts ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1182
Author(s):  
Julien G. Mahy ◽  
Louise Lejeune ◽  
Tommy Haynes ◽  
Nathalie Body ◽  
Simon De Kreijger ◽  
...  
Keyword(s):  
Industrial Revolution ◽  
Organic Pollutant ◽  
Sol Gel ◽  
Critical Issue ◽  
Water Remediation ◽  
Technological Advances ◽  
Calcination Step ◽  
Biological Remediation ◽  
Sol Gel Process ◽  
Nitrophenol Degradation

Since the Industrial Revolution, technological advances have generated enormous emissions of various pollutants affecting all ecosystems. The detection and degradation of pollutants has therefore become a critical issue. More than 59 different remediation technologies have already been developed, such as biological remediation, and physicochemical and electrochemical methods. Among these techniques, advanced oxidation processes (AOPs) have been popularized in the treatment of wastewater. The use of ZnO as a photocatalyst for water remediation has been developing fast in recent years. In this work, the goals are to produce ZnO photocatalysts with different morphologies, by using a green sol-gel process, and to study both the influence of the synthesis parameters on the resulting morphology, and the influence of these different morphologies on the photocatalytic activity, for the degradation of an organic pollutant in water. Multiple morphologies were produced (nanotubes, nanorods, nanospheres), with the same crystalline phase (wurtzite). The most important parameter controlling the shape and size was found to be pH. The photoactivity study on a model of pollutant degradation shows that the resulting activity is mainly governed by the specific surface area of the material. A comparison with a commercial TiO2 photocatalyst (Evonik P25) showed that the best ZnO produced with this green process can reach similar photoactivity without a calcination step.

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.

scholarly journals High Nanopore Volume Tetrethoxysilane Based Aerogels Prepared with Addition of N, N-Dimethylformamide at Different Stage of the Sol-Gel Process

2021 ◽  
Author(s):  
Chaoshuai LEI ◽  
Enshuang ZHANG ◽  
Hongyan HUANG ◽  
Xuyang JI ◽  
Lijuan HE ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Sol Gel ◽  
Supercritical Drying ◽  
Silica Aerogels ◽  
Drying Process ◽  
Chemical Additive ◽  
Structure Control ◽  
Colloid Particles ◽  
Sol Gel Process ◽  
Uniform Pore Size

Using tetraethoxysilane (TEOS) as a precursor, silica aerogels were synthesized via the sol-gel polymerization followed by supercritical drying process. During the polymerization period, N, N-dimethylformamide (DMF), acting as a chemical additive for the structure control, was introduced in the hydrolysis step and condensation step, respectively. As a result, the nanopore volumes for the pores smaller than 100 nm were up to 6.0 cm3/g and 5.7 cm3/g for the samples that produced with DMF addition in the hydrolysis step and condensation step, while the value for the sample without DMF was only 4.6 cm3/g. Besides, the sample with DMF addition in the condensation step possessed more uniform pore size distribution while compared with that with DMF addition in the hydrolysis step. DMF can provide a shielding layer around the colloid particles through hydrogen bonds, inhibiting the aggregation of colloid particles and the enlarging of pore sizes.

Microstructural Characterization and Properties of Silica Aerogels Doped with Nano-ITO Powder

2011 ◽  
Vol 284-286 ◽  
pp. 662-666 ◽  
Author(s):  
Ben Lan Lin ◽  
Sheng Cui ◽  
Xiao Dong Shen ◽  
Ying Li Leng ◽  
Xue Yong Liu ◽  
...  
Keyword(s):  
Average Pore Size ◽  
Sol Gel ◽  
Microstructural Characterization ◽  
Supercritical Drying ◽  
Silica Aerogels ◽  
Average Pore ◽  
Sol Gel Process ◽  
Main Factors ◽  
20 Nm ◽  
Radiation Conductivity

Silica-based aerogels doped with nano-ITO powder were synthesized using sol–gel process followed by supercritical drying. The main factors were studied including dosage of compling agent KH570 and ITO. The result shows that thermal radiation conductivity is 0.02659 W/(m•K) with ITO of 44.44% after 10 g ITO powder is modified with 1 mL KH570. The microstructure and physical characteristic of the SiO2–ITO aerogels were characterized by FTIR, SEM, TG-DSC and BET. Their specific surface was in the range of 513–775m2/g and their average pore size was mainly 20 nm. Nano-ITO powders are physically embedded by SiO2aerogels.

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