Method for preparing hydrophobic silica aerogel from rice husk ash based aquagel

A hydrophobic silica and hydrogel technology, applied in the field of surface group modification of gel pores and drying at atmospheric pressure, porous gel, and sol-gel method to prepare aerogels, which can solve difficult scale production, dangerous Large, complex equipment and other problems, to achieve the effect of low price, low cost and simple process

Inactive Publication Date: 2009-01-21
TONGJI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although both methods use cheap rice husk as the silicon source, they still use supercritical drying, which has high cost, complicated equipment, high risk, and is difficult to be suitable for large-scale production.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0032] Take 100g of hydrogel prepared from rice husk ash, add 300ml of ethanol, soak for 24 hours, filter the gel, add 150ml of methyltriethoxysilane for surface treatment, and treat the gel at 60°C for 24 hours The gel was taken out and placed under an infrared drying lamp at a temperature of 110°C in the drying area, and hydrophobic silica airgel was obtained after 1 hour. The degree of hydrophobicity was measured by the methanol-water solution method, and it reached 40%. Its specific surface area is 512m 2 / g, apparent density 0.093g / cm 3 , the pore size distribution peak is 18.3nm.

example 2

[0034] Take 100g of hydrogel prepared from rice husk ash, add 300ml of ethanol, soak for 24 hours, filter the gel, add 250ml of hexamethyldisiloxane and trimethylchlorosilane for surface treatment, after 50 ℃ treatment for 8 hours, take out the gel, put it under the infrared drying lamp, the temperature of the drying area is 100 ℃, and obtain the hydrophobic silica airgel after 1 hour. The degree of hydrophobicity was measured by the methanol-water solution method, reaching 45%. Its specific surface area is 567m 2 / g, apparent density 0.077g / cm 3 , the pore size distribution peak is 23.4nm.

example 3

[0036] Take 100g of hydrogel prepared from rice husk ash, add 300ml of methanol, soak for 24 hours, filter the gel, add 400ml of dimethyldiethoxysilane for surface treatment, and treat it at 80°C for 24 hours. The gel was taken out and placed under an infrared drying lamp at a temperature of 110° C. in the drying area, and a hydrophobic silica airgel was obtained after 2 hours. The degree of hydrophobicity was measured by the methanol-water solution method, and it reached 40%. Its specific surface area is 512m 2 / g, apparent density 0.088g / cm 3 , the pore size distribution peak is 19.0nm.

[0037] The present invention abandons the process of water washing, which is beneficial to reduce the process, reduce the production cost and shorten the production cycle, and is beneficial to the formation of the airgel internal porous structure and the formation of the water injection surface, which is the key to the quality control of airgel products. We used solvent replacement and s...

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Abstract

The invention provides a method for preparing hydrophobic silicon dioxide aerogel by rice hull ash based water gel. The silicon dioxide water gel obtained by taking rice hull ash as materials is subjected to solvent replacement, surface finish in the siloxane phase and normal-pressure drying treatment to prepare the silicon dioxide aerogel with hydrophobic characteristics. For the aerogel prepared, the specific surface area reaches between 500 and 1000m<2>/g, the volume density is between 0.08 and 0.3g/cm<3>, and the sizes of the micropores are mainly distributed in the range of between 1 and 100nm. The method adopts advanced technologies of the solvent replacement, the surface finish and the preparation of the normal-pressure aerogel, thereby unnecessarily using expensive organic resources, avoiding the use of supercritical drying equipment which is commonly used in the convention preparation of the silicon dioxide aerogel and has problems of high price, low efficiency and high risk and the technological investment, and obviously lowering production risk and production cost. Moreover, the method also has the advantages of simple process, strong manageability and suitable mass production and application.

Description

technical field [0001] The invention belongs to the technical field of preparation of novel nanometer materials, and relates to airgel preparation by a sol-gel method, porous gel, surface group modification of gel holes and normal-pressure drying method. Background technique [0002] Silica airgel is a new type of nanoporous material, its main feature is a three-dimensional nanoporous space network structure with high permeability, the porosity can reach more than 90%, and the specific surface area can reach 1000m 2 / g or more. Due to the existence of nanopores and high specific surface area, airgel has many excellent properties, which make airgel have singular properties in thermal, electrical, acoustic, optical and other aspects. These singular properties make it useful in energy, information, environmental protection, It has great application potential in the fields of medicine, pesticide, metallurgy, catalysis, construction and scientific experiments. Hydrophobic silic...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/14
Inventor 倪星元王博沈军张志华王际超
Owner TONGJI UNIV
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