A method for preparing silica airgel by drying at low temperature and normal pressure with straw as raw material

A technology of low temperature and atmospheric pressure, silicon dioxide, applied in the direction of silicon dioxide, silicon oxide, etc., can solve the problems of low efficiency of multi-step replacement, high risk of equipment, difficulty in large-scale production, etc., and achieve high waste utilization rate, The preparation method is simple and the effect of excellent performance

Active Publication Date: 2016-05-25
CHANGZHOU UNIV
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Problems solved by technology

Domestic research on the extraction and utilization of high value-added components of straw waste and the development of high-performance composite materials is currently less. Scholars from Harbin Institute of Technology, Wuhan University of Technology, Chinese Academy of Forestry and other units have carried out corn straw extraction of silicon, Preparation of thermal insulation and environmental protection coatings, water glass, white carbon black and other silicon and carbon comprehensive extraction related technology research, Nanchang University, Tsinghua University, Harbin Normal University, etc. have carried out similar research using rice husk ash, some Chinese patents of Wang Tao ( Application No. 03127920.1, Publication No. CN1449997A, Publication No. CN1724353A) introduced supercritical drying with rice husk ash as a silicon source, high cost, dangerous equipment, and difficult large-scale production
In Chinese patents, Ni Yuanxing (application number CN20081004222.4), Jin Chengli (application number CN200810061201.7 and application number CN200810061202.1) are all about rice husk ash as a silicon source, and the method of multi-step solvent replacement modification has not been applied to straw , low efficiency of multi-step replacement, high cost, and poor environmental protection
At present, there is no patent report on the preparation of silicon airgel materials from straw

Method used

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  • A method for preparing silica airgel by drying at low temperature and normal pressure with straw as raw material
  • A method for preparing silica airgel by drying at low temperature and normal pressure with straw as raw material
  • A method for preparing silica airgel by drying at low temperature and normal pressure with straw as raw material

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] (1) Straw pretreatment

[0025] Put the wheat straw into the muffle furnace, calcine at 400°C for 20 minutes in an air atmosphere, and take it out for rapid air cooling.

[0026] (2) Take 3g of powdered straw ash, stir and wash it with 100mL of 0.44mol / L dilute hydrochloric acid solution at 50°C for 60 minutes, and separate it with suction filtration equipment.

[0027] (3) Wash the washed wet filter residue directly into a beaker with 50 mL of deionized water, and prepare a 0.8 mol / L sodium hydroxide solution with 50 mL of deionized water, and put it into a boiling state to react for 3 hours. After the reaction, use suction filtration equipment to separate, and continue to wash the filter residue into the filtrate with 50 mL of deionized water.

[0028] (4) The obtained filtrate was concentrated under distillation to 20 mL, and 20 mL of tetraethoxysilane was added for silicon replenishment treatment.

[0029] (5) Pass the concentrated solution through IR-120H cationi...

Embodiment 2

[0037] (1) Straw pretreatment

[0038] Put the corn stalks into the muffle furnace, calcine at 500°C for 60 minutes in an air atmosphere, and take them out for rapid air cooling.

[0039] (2) Take 3 g of powdered straw ash, stir and wash it with 100 mL of 0.25 mol / L dilute hydrochloric acid solution at 50° C. for 60 minutes, and separate it with suction filtration equipment.

[0040] (3) Wash the washed wet filter residue directly into a beaker with 50 mL of deionized water, and prepare a 0.4 mol / L sodium hydroxide solution with 50 mL of deionized water, and put it into a boiling state to react for 5 hours. After the reaction, use suction filtration equipment to separate, and continue to wash the filter residue into the filtrate with 50 mL of deionized water.

[0041] (4) Concentrate the obtained filtrate to 20 mL under distillation. Add 4ml of tetraethoxysilane for silicon replenishment treatment.

[0042] (5) Pass the concentrated solution through the IR-120H cationic res...

Embodiment 3

[0048] (1) Put the rice straw into the muffle furnace and calcinate at 200°C for 500 minutes in an air atmosphere, take it out and cool it quickly after calcining;

[0049] (2) The straw ash obtained by calcining in step (1) is stirred and cleaned with 0.01mol / L dilute hydrochloric acid solution, and then the solid-liquid separation is carried out through suction filtration equipment, wherein the solid-liquid ratio of straw ash to dilute hydrochloric acid is 100g: 2-20L ;

[0050] (3) The wet filter residue cleaned in step (2) is directly added to 0.2mol / L sodium hydroxide solution, wherein the solid-to-liquid ratio of the wet filter residue and sodium hydroxide solution is 100g: 2-20L, and the above solution is boiled Down reaction 20 minutes, after reaction, separate with suction filtration equipment;

[0051] (4) The filtrate obtained by step (3) separation is concentrated under distillation, according to SiO 2 : Na 2 0 molar ratio adds 20mL trimethoxy silicon to carry o...

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Abstract

The invention relates to a method for preparing silica aerogel from straws as raw materials by virtue of low-temperature atmospheric-pressure drying. The method comprises the following steps: firstly carrying out low-temperature ashing treatment on agricultural waste straws as the raw materials, cleaning with a low-concentration hydrochloric acid solution, leaching a hydrosol by controlling the content of an alkali to prepare the hydrosol through ion-exchange treatment, directly carrying out one-step silanization treatment on the obtained hydrosol with an alkane solvent having low surface tension and high saturated vapor pressure and finally carrying out atmospheric-pressure drying to obtain the silica aerogel. The obtained silica aerogel material has excellent performance and can be used as materials in building, medicine, water treatment, industrial heat insulation, chemical engineering catalysis. The method, compared with other preparation methods of the aerogel, has the advantages of simple overall process, low cost, high specific surface area, reasonable pore structure, low apparent density, high hydrophobicity and high utilization rate of wastes and is suitable for large-scale production and applications.

Description

technical field [0001] The invention relates to the field of chemical material preparation, in particular to a method for preparing silicon dioxide airgel by drying waste crop stalks at low temperature and under normal pressure. Background technique [0002] At present, emission reduction and energy saving have become two major issues restricting social development. On this basis, it is of great practical significance and social value to study the use of waste to produce high value-added energy-saving insulation materials. China's annual output of crop straw is about 700 million tons, ranking first in the world. Of the straw harvested every year, 28 million tons are used for papermaking, 213 million tons are used as feed or feed raw materials, 108.9 million tons are returned to the field for manure and collection losses, and the total amount of other unused is 376.1 million tons. China's rural areas mainly include rice straw, wheat straw, and corn straw, of which corn straw...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/16
Inventor 赵善宇徐海珣朱平华伍君勇郑猛张鑫鑫
Owner CHANGZHOU UNIV
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