Optically transparent silica aerogels based on sodium silicate by a two step sol–gel process and ambient pressure drying

Bangi, Uzma K.H.; Jung, In Keun; Park, Chang Sun; Baek, Seungsu; Park, Hyung Ho

doi:10.1016/j.solidstatesciences.2012.12.016

Cited by 66 publications

(31 citation statements)

References 19 publications

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“…Silica aerogel preparation was carried out by the sol-gel process (13,(16)(17)(18). At first, the original sol was produced by preparing a saturated solution of Na 2 SiO 3 .…”

Section: Adsorbent Preparationmentioning

confidence: 99%

“…There are various methods for phenol removal from aqueous solutions, such as Fenton-based technologies (3), ozonation (4), coagulation (5), biological processes (6), adsorption (7), electro-oxidation (8), and electrocoagulation (9). ity (up to 99%), and high modification capability (12)(13)(14). Up to now, this adsorbent has been widely applied to remove various toxic compounds, such as heavy metals (14), Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX) compounds (15), dyes (11), and so on.…”

Section: Introductionmentioning

confidence: 99%

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Preparation, Characterization, and Application of Silica Aerogel for Adsorption of Phenol: An In-Depth Isotherm Study

et al. 2018

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This study evaluated silica aerogel as an adsorbent for phenol removal from aqueous solutions. Silica aerogel was prepared through the sol-gel process and characterized by different analyses. Then, it was used for phenol removal under various conditions of operational parameters. Also, twelve isotherm parameters were employed to describe the behavior of phenol-silica aerogel adsorption system. The chemical structural analysis confirmed -OH functional groups in amorphous SiO2 and proved the adsorption of phenol onto the surface of silica aerogel. The findings of the adsorptive behavior of silica aerogel toward phenol showed increasing pH, up to 8.5, and contact time, and adsorbent dose increased the phenol removal. The removal efficiency reached over 90% when phenol concentration was below 50 mg L -1 . The reaction kinetics followed the pseudo-first order model. The isotherm study showed that equilibrium adsorption data were well-described by Freundlich and Halsey equations, among two-parameter isotherms, and Hill, Sips, and Koble-Corrigan, among three-parameter isotherms. Jovanovic and BET were the worst isotherm models for prediction of experimental equilibrium data. The maximum adsorption capacity of 75.23 mg.g -1 was calculated in phenol-silica aerogel adsorption system. The study showed silica aerogel as an efficient adsorbent to remove phenol from phenol-containing solutions.

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“…Silica aerogel preparation was carried out by the sol-gel process (13,(16)(17)(18). At first, the original sol was produced by preparing a saturated solution of Na 2 SiO 3 .…”

Section: Adsorbent Preparationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Preparation, Characterization, and Application of Silica Aerogel for Adsorption of Phenol: An In-Depth Isotherm Study

et al. 2018

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“…Ambient pressure drying (APD) is another option to produce silica aerogel, and water glass‐based silica aerogels by APD has been extensively studied by many researchers . The APD relies on surface modification and solvent exchange processes that are not only tedious but also economically unfavorable.…”

Section: Figurementioning

confidence: 99%

“…The APD relies on surface modification and solvent exchange processes that are not only tedious but also economically unfavorable. Since surface modification agents (typically, trimethylchlorosilane (TMCS) or hexamethyldisilazane (HMDS)) can be transported within the silica hydrogel only by diffusion, APD requires processing times longer than a few or sometimes even tens of hours . Recently, some groups have attempted to reduce the processing time of APD via a co‐precursor method …”

Section: Figurementioning

confidence: 99%

Fast Synthesis of Spherical Silica Aerogel Powders by Emulsion Polymerization from Water Glass

Lee

Kim²,

Lee³

et al. 2018

ChemistrySelect

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In this study, a fast synthesis technique for silica aerogel powder was proposed that reduces the length of the tedious surface modification and solvent exchange processes. Spherical silica aerogel powder could be fabricated by an emulsion polymerization method from water glass and n-hexane. A stable water glass-in-hexane emulsion with a water glass to hexane ratio of 5:5 was fabricated using the surfactant, sorbitan monooleate (Span80). It was found that acetic acid and isopropanol catalysts for the hydrolysis and condensation of water glass droplets dispersed in the emulsion were crucial for the synthesis of the spherical silica aerogel powder with a narrow particle size distribution and for reducing production time. In addition, the particle size of the spherical silica aerogel could be controlled by changing the water glass droplet size.A silica (SiO 2 ) aerogel is an ultra-porous (90-99% of theoretical density) material with a 3-dimensional network structure of silica nanoparticles. [1] Because of its interesting characteristics such as high specific surface area, low thermal conductivity, low dielectric constant, and low refractive index, it has received wide attention within various fields as a promising material for catalysis, [2,3] adsorption, [4,5] heat insulation [6,7] and drug delivery. [8"9] Silica aerogels are normally synthesized via a sol-gel route from silicon alkoxides such as tetramethylorthosilicate (TMOS) or tetraethylorthosilicate (TEOS). A silica wet gel is formed as a result of a hydrolysis and condensation process of the silicon alkoxide molecules. The silica aerogel can then be obtained by a supercritical drying process with carbon dioxide (CO 2 ). [10,11] However, the alkoxide-derived silica aerogels use expensive precursors, and the supercritical drying process requires long processing times (low heating and depressurization rates) [12,13] which increases the overall cost of the aerogel.Ambient pressure drying (APD) is another option to produce silica aerogel, and water glass-based silica aerogels by APD has been extensively studied by many researchers. [14][15][16][17] The APD relies on surface modification and solvent exchange processes that are not only tedious but also economically unfavorable. Since surface modification agents (typically, trimethylchlorosilane (TMCS) or hexamethyldisilazane (HMDS)) can be transported within the silica hydrogel only by diffusion, APD requires processing times longer than a few or sometimes even tens of hours. [14][15][16] Recently, some groups have attempted to reduce the processing time of APD via a co-precursor method. [18][19][20] Huber et al. proposed a one-pot synthesis technique for a silica aerogel granulate, which could reduce solvent use and production time to within 4 h. However, they used an expensive precursor like polyethoxysiloxane (PEDS), and the morphology of the synthesized silica aerogel granulate was irregular. [21] Pan et al. prepared a silica aerogel powder via APD from water glass within 4 h. [22] Although the mechanical cru...

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“…In recent years and after the production of silica aerogels under ambient pressure drying (APD) condition by Deshpande et al . in 1993, numerous researches and developments have taken place on silica aerogel and its composites . Such endeavors could be categorized into three main branches; first are the ones aimed at reducing production cost through synthesizing in ambient pressure and also utilizing cheaper initiating materials such as water‐glass .…”

Section: Introductionmentioning

confidence: 99%

Preparation and characterization of polyurethane/silica aerogel nanocomposite materials

Dourbash

Buratti

Belloni

et al. 2016

J of Applied Polymer Sci

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In this investigation, silica aerogel (SA)/Rigid Polyurethane (PUR) foam composites and silica aerogel/Polyurethane (PU) composites were prepared by dry mixing of granular and grinded silica aerogels with polyol part. They were then combined with diisocyanate part. Three different types of PUR foams and an elastomeric coating grade of PU were studied as well. Results show that thermal conductivity of foams did not decrease by adding silica aerogel. It even increased for some grades which is assumed to be due to the change in cell configuration of these foams. It was also found that sound insulation performance of these cellular composites did not improve significantly. Unlike foam composites, addition of silica aerogel into elastomeric PU improved its thermal and acoustic insulation properties. Because of the more promising properties of elastomeric PU composites, further examinations including measurements of compression strength and water contact angle of silica aerogel/PU composites were also taken. Final results showed a significant improvement in general properties of PU coatings by adding little amounts of silica aerogel (1-4 wt %). V C 2016Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44521.

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Optically transparent silica aerogels based on sodium silicate by a two step sol–gel process and ambient pressure drying

Cited by 66 publications

References 19 publications

Preparation, Characterization, and Application of Silica Aerogel for Adsorption of Phenol: An In-Depth Isotherm Study

Preparation, Characterization, and Application of Silica Aerogel for Adsorption of Phenol: An In-Depth Isotherm Study

Fast Synthesis of Spherical Silica Aerogel Powders by Emulsion Polymerization from Water Glass

Preparation and characterization of polyurethane/silica aerogel nanocomposite materials

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