Cost-effective synthesis of silica aerogels from fly ash via ambient pressure drying

Shi, Fei; Liu, Jingxiao; Song, Kai; Wang, Zhenyu

doi:10.1016/j.jnoncrysol.2010.08.005

Cited by 73 publications

(21 citation statements)

References 34 publications

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“…Generally, the most widely used sources of silicon, the so-called precursors are alkoxysilanes such as tetraethoxysilane or tetraethylsilicate TEOS and tetramethoxysilane TMOS [24,25] or the inorganic sodium silicate (waterglass) [26]. More recently, waste products such as oil shale ash [27], rice husk ash [28,29] or fly ash [30] have been investigated as inexpensive alternatives. From a more general point of view, such exotic precursors make part of an eco-design strategy for silica aerogels elaboration [31].…”

Section: Overview Of Common Chemical Synthesis Methodsmentioning

confidence: 99%

Aerogel-based thermal superinsulation: an overview

Koebel

Rigacci

Achard

2012

J Sol-Gel Sci Technol

582

321

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International audienceThis review is focused on describing the intimate link which exists between aerogels and thermal superinsulation. For long, this applied field has been considered as the most promising potential market for these nanomaterials. Today, there are several indicators suggesting that this old vision is likely to become reality in the near future. Based on recent developments in the field, we are confident that aerogels still offer the greatest potential for non-evacuated superinsulation systems and consequently must be considered as an amazing opportunity for sustainable development. The practical realization of such products however is time-consuming and a significant amount of R&D activities are still necessary to yield improved aerogel-based insulation products for mass markets

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Section: Overview Of Common Chemical Synthesis Methodsmentioning

confidence: 99%

Aerogel-based thermal superinsulation: an overview

Koebel

Rigacci

Achard

2012

J Sol-Gel Sci Technol

582

321

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“…Generally, silica aerogel is produced by a sol-gel technique with silicon alkoxides, such as tetraethoxysilane (TEOS) [ 6 , 7 ] or tetramethoxysilane (TMOS) [ 8 , 9 ] as precursors. Recently, sodium silicate [ 10 , 11 , 12 ] or solid wastes such as oil shale ash [ 13 ], fly ash [ 14 ], bagasse ash [ 15 ], and rice husk ash [ 16 ] have also been used as raw materials to prepare silica aerogels. Drying process, including either supercritical drying (SD) [ 17 ] or ambient pressure drying (APD) [ 18 , 19 ], plays a critical role in the manufacture of silica aerogels.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Silica Aerogels by Ambient Pressure Drying without Causing Equipment Corrosion

et al. 2018

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The silica aerogels were prepared via a sol-gel technique and ambient pressure drying by using industrial solid wastes, dislodged sludges, as raw materials. A strategy was put forward to reduce the corrosion of equipment during the drying procedure. The pore structure, hydrophobicity, and thermal insulation property of the obtained samples were investigated in detail. The results show that the corrosion can be effectively avoided by using an equimolar mixture of trimethylchlorosilane (TMCS) and hexamethyldisilazane (HMDS) as silylation agents. At a Si:TMCS:HMDS molar ratio of 1:0.375:0.375, the silica aerogels possess a desirable pore structure with a pore volume of 3.3 ± 0.1 cm3/g and a most probable pore size of 18.5 nm, a high hydrophobicity with a water contact angle of 144.2 ± 1.1°, and a low thermal conductivity of 0.031 ± 0.001 W/(m∙K).

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“…[1][2][3][4][5][6][7] Because of these remarkable properties, experimental and theoretical investigations involving aerogels are mostly focused on silicon compounds. [1][2][3][4][5][6][7] Because of these remarkable properties, experimental and theoretical investigations involving aerogels are mostly focused on silicon compounds.…”

Section: Introductionmentioning

confidence: 99%

“…Silica aerogels are low-density, high-porosity materials and possess desirable physical properties, such as extremely low thermal conductivity, high acoustic impedance, large specific surface area, and low relative dielectric constants. [1][2][3][4][5][6][7] Because of these remarkable properties, experimental and theoretical investigations involving aerogels are mostly focused on silicon compounds. [8] Silica aerogels are ideal candidates for various applications, such as thermal superinsulators, adsorbents, sensors, catalyst carriers, and inorganic fillers.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of Silicon Alkoxide Hydrolysis–Oligomerization Reactions: A DFT Investigation

2012

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Silica aerogels possess a variety of unique and remarkable properties, but the mechanisms of silicon alkoxide, Si(OR)(4), hydrolyses and oligomerization in the initial stage of sol-gel processes are still not well understood. On the basis of density functional theory calculations at the B3LYP/6-31G(d,p)//B3LYP/6-311++G(d,p) basis set level, the hydrolysis and oligomerization reactions of Si(OR)(4) in neutral, acidic, and alkaline solutions were systematically investigated and we found that in acidic solutions the precursor Si(OCH(3))(4) was inclined to hydrolyze rather than to condense and the hydrolysis processes were energetically more favorable than the neutral ones. In alkaline solutions, the hydrolysis products oligomerize through an S(N)1 dimerization mechanism and the condensation rates are fast to form denser colloidal aerogels. Our calculations also testify that the subsequent cyclization reactions are energetically unfavorable.

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Cost-effective synthesis of silica aerogels from fly ash via ambient pressure drying

Cited by 73 publications

References 34 publications

Aerogel-based thermal superinsulation: an overview

Aerogel-based thermal superinsulation: an overview

Preparation of Silica Aerogels by Ambient Pressure Drying without Causing Equipment Corrosion

Mechanisms of Silicon Alkoxide Hydrolysis–Oligomerization Reactions: A DFT Investigation

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