Preparation of Sodium Silicate–Based Aerogels Using a Two‐Step Sol–Gel Process and Ambient Pressure Drying

2019 ◽  
Vol 387 (1) ◽  
pp. 1800226 ◽  
Author(s):  
Uzma K. H. Bangi ◽  
Shivani S. Pandit ◽  
Dhanashri B. Bagal ◽  
Hyung‐Ho Park
Keyword(s):  
Sodium Silicate ◽  
Ambient Pressure ◽  
Sol Gel ◽  
Ambient Pressure Drying ◽  
Sol Gel Process

Preparation of monolithic titania aerogels with high surface area by a sol–gel process combined surface modification

RSC Advances ◽  
2014 ◽  
Vol 4 (62) ◽  
pp. 32934-32940 ◽  
Author(s):  
Hui Yang ◽  
Wenjun Zhu ◽  
Sai Sun ◽  
Xingzhong Guo
Keyword(s):  
Surface Modification ◽  
Surface Area ◽  
Ambient Pressure ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Ambient Pressure Drying ◽  
Sol Gel Process

Monolithic titania (TiO2) aerogels with high surface area were successfully synthesized by the sol–gel process combined surface modification, followed by ambient pressure drying.

Effects of Surfactants on the Synthesis of Silica Aerogels Prepared by Ambient Pressure Drying

2012 ◽  
Vol 512-515 ◽  
pp. 1625-1630
Author(s):  
Hua Zheng Sai ◽  
Li Xing ◽  
Jun Hui Xiang ◽  
Fu Shi Zhang ◽  
Li Jie Cui ◽  
...  
Keyword(s):  
Ambient Pressure ◽  
Sol Gel ◽  
Drying Shrinkage ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Ammonium Bromide ◽  
High Porosity ◽  
Free Silica ◽  
Sol Gel Process ◽  
Cetyltrimethyl Ammonium

In this research, aerogels were synthesized by a two-step sol-gel process without supercritical conditions. During the process, tetraethoxysilane (TEOS) was used as precursor, and different surfactants, i.e. cetyltrimethyl ammonium bromide (CTAB) and polyethylene glycol–600 (PEG–600), were used as dopants respectively. In order to minimize the drying shrinkage and preserve the high porosity structure, the surface of the gels was modified by trimethylchlorosilane (TMCS) before the ambient pressure drying (APD). The effect of surfactent on the structure of the resulting aerogels was investigated. The aerogels which involved surfactants exhibited resistance to cracking during the APD of the alcogels. The modification by TMCS has been confirmed using Infrared (IR) spectroscopy. The porous structure of aerogels was investigated by Brunauer-Emmett- Teller (BET) instrument, differential scanning calorimeter (DSC) and scanning electron micrograph (SEM). The results indicated that surfactants as dopants could significantly affect the structure and optical property of aerogels and be beneficial for obtaining crack-free silica aerogels via ambient pressure drying process.

Physical properties of sodium silicate based silica aerogels prepared by single step sol–gel process dried at ambient pressure

2009 ◽  
Vol 476 (1-2) ◽  
pp. 397-402 ◽  
Author(s):  
Jyoti L. Gurav ◽  
A. Venkateswara Rao ◽  
A. Parvathy Rao ◽  
D.Y. Nadargi ◽  
S.D. Bhagat
Keyword(s):  
Physical Properties ◽  
Sodium Silicate ◽  
Ambient Pressure ◽  
Sol Gel ◽  
Silica Aerogels ◽  
Single Step ◽  
Sol Gel Process

Hydrophobic Flexible Silica Aerogels Felts Fabricated by Ambient Pressure Drying

2013 ◽  
Vol 709 ◽  
pp. 32-35
Author(s):  
Xiao Yun Wu ◽  
Yu Xi Yu ◽  
De Qian Guo ◽  
Yong Chen
Keyword(s):  
Aqueous Ammonia ◽  
Ambient Pressure ◽  
Sol Gel ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Ethanol Solution ◽  
Hydrophobic Properties ◽  
Ph Values ◽  
Sol Gel Process ◽  
Hexane Solution

Hydrophobic flexible silica aerogels felts were fabricated successfully by two-steps sol-gel process via ambient pressure drying. First of all, the sol with various pH values was obtained from tetraethylorthosilicate (TEOS) as silicon source, hydrochloric acid/aqueous ammonia ethanol solution as catalysts. Then glass fiber felts was incorporated into the sol to increase the mechanical properties of silica aerogel. After the completion of solvent exchange and surface modification by using trimethylchlorosilane (TMCS)/n-hexane solution, the gel felts were dried under ambient pressure. The samples show excellent hydrophobic properties.

Hydrophobic Silica Aerogels by Ambient Pressure Drying

2015 ◽  
Vol 830-831 ◽  
pp. 476-479
Author(s):  
Srinivasan Nagapriya ◽  
M.R. Ajith ◽  
H. Sreemoolanadhan ◽  
Mariamma Mathew ◽  
S.C. Sharma
Keyword(s):  
Surface Area ◽  
Atmospheric Pressure ◽  
Polar Solvent ◽  
Ambient Pressure ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Sol Gel Process

Silica aerogels have been prepared through sol-gel process by polymerization of TEOS in the presence of NH4F and NH4OH as catalysts. The solvent present in the gel is replaced by ethanol followed by a non-polar solvent such as n-hexane prior to solvent modification step. Gels are made hydrophobic by treating them with HMDZ to prevent rupture during drying, which has been confirmed by FTIR. Gels are then washed and dried carefully in a PID controlled oven at atmospheric pressure. The ageing duration and solvent exchange combinations are optimized to yield crack-free gels prior to drying. Aerogels are characterized for density, specific surface area, pore volume, pore size, thermal stability and contact angle. Hydrophobic, high surface area (570 m2/g), low density (0.07 g/cm3) silica aerogels are synthesized by using optimized mole ratio of precursors and catalysts. Silica aerogel granules (1-3 mm) as well as monoliths (Ф~35 mm) could be produced through ambient pressure drying of gels.

Study of Synthesis of SiO2 Aerogel from Coal Gangue at an Ambient Pressure

2014 ◽  
Vol 997 ◽  
pp. 614-617 ◽  
Author(s):  
Jin Meng Zhu ◽  
Hui Wu Cai ◽  
Nan Nan Dang
Keyword(s):  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Ambient Pressure ◽  
Sol Gel ◽  
Value Added ◽  
Ambient Pressure Drying ◽  
Coal Gangue ◽  
High Porosity ◽  
Excellent Property ◽  
Temperature Time

The hydrophobic SiO2 aerogel was prepared by using coal gangue as the starting material—which is viewed as waste in most coal mining and preparation plant—via ambient pressure drying through sol-gel method. The effects of different temperature, time to keep the temperature,vary in mass ratio of coal gangue to sodium hydroxide on the leaching ratio of SiO2 from coal refuses are discussed in this paper. Results showed that the leaching ratio of SiO2 extracted from gangue will be made up to 35.23% compared with the other tests on the condition that the temperature is given 750°C, holding time 2h, the value of ratio of coal gangue to sodium hydroxide 1:0.8, concentration of NaOH 20%. Trimethylchlorosilane (TMCS) is used as modifier to obtain hydrophobicity through solvent exchange and surface modification. We achieved SiO2 aerogel with low density of 0.2559g/cm3, high porosity 88.97%,Strong hydrophobicity (contact angle with water 140.61。) respectively, which demonstrated that the final product exhibits excellent property. Differences among SiO2 aerogel properties were discussed between industrial sodium silicate as precursor and sodium silicate drew from coal gangue as precursor. Results revealed that the the latter is better than the former on properties .Our work provided a potential way to synthetize high value-added product from abandoned by-product coal gangue.

The Microwave-Assisted Preparation and Properties of SiO2 Aerogels by Fractional Modification

2010 ◽  
Vol 148-149 ◽  
pp. 1152-1162 ◽  
Author(s):  
Wen Zhi Zheng ◽  
Li Chen ◽  
Xiang Hua Huang ◽  
Lei Fu
Keyword(s):  
Ambient Pressure ◽  
Sol Gel ◽  
Ambient Pressure Drying ◽  
Base Catalysis ◽  
Raw Material ◽  
Microwave Method ◽  
Scanning Calorimetry ◽  
Hydrophobic Sio2 ◽  
Water Bath Heating ◽  
Fractional Modification

Under microwave radiation and using trimethyl chlorosilane as modifier, hydrophobic SiO2 aerogel was prepared through fractional hydrophobic modification and ambient pressure drying of the raw material, tetraethoxysilane (TEOS), in the process of sol-gel and acid-base catalysis. Hydrophilic SiO2 aerogels were also prepared using the microwave method and water bath heating method. The SiO2 aerogels prepared using the three methods, including their morphology and chemical composition, were analyzed and compared using scanning electron microscopy, Brunauer-Emmett-Teller analysis method, Fourier transform infrared spectroscopy, X-ray diffraction, and themogravimetric-differential scanning calorimetry. The results indicate that by adopting the microwave reaction, the specific surface area of the SiO2 aerogels was effectively increased and the structure of the internal nanoscale pores of petal-coated shape was found to exist under the dense external surface of the SiO2 aerogels. Thermal stability of the hydrophobic SiO2 aerogels prepared through fractional modification assisted by the microwave method was increased with the hydrophobic angle at153°, which showed super hydrophobicity.

A silica aerogel as an extractive coating for in-tube solid-phase microextraction to determine polycyclic aromatic hydrocarbons in water samples

2019 ◽  
Vol 11 (45) ◽  
pp. 5784-5792 ◽  
Author(s):  
Xiangping Ji ◽  
Juanjuan Feng ◽  
Chunying Li ◽  
Sen Han ◽  
Jiaqing Feng ◽  
...  
Keyword(s):  
Silica Aerogel ◽  
Solid Phase Microextraction ◽  
Solid Phase ◽  
Ambient Pressure ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Ambient Pressure Drying ◽  
Acid Base ◽  
Polycyclic Aromatic

A silica aerogel with high surface area was prepared by an acid–base two-step catalytic sol–gel method under ambient pressure drying.

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