A method for preparing aerogel felt and aerogel insulation board using humus as raw material

Abstract

The invention provides a method for preparing an aerogel insulation board by taking humus as a raw material, and water glass and aerogel felt formed in the process. Specifically, the humus treated by thermal desorption is pretreated by an alkali melting method, the humus is mixed with sodium carbonate or sodium hydroxide for grinding, melting and water cooling, and then the sintered product is dissolved by acid and solid-liquid separation is performed to obtain a sodium silicate solution containing impurities, and the water glass solution is obtained after further filtration; and then the aerogel felt and aerogel insulation board for construction are further prepared. The method not only has the advantages of low raw material price and abundant sources, and overcomes the disadvantage of high preparation cost in the past, but also the prepared aerogel material is a high-performance insulation material product, which increases the added value of the humus, makes the humus resource-based, and turns waste into treasure, and can be used as a new type of high-quality energy-saving building material.

Description

Technical Field

[0001] The invention belongs to the field of nano material preparation technology, and in particular relates to a method for preparing an aerogel insulation board by taking humus as a raw material. Background Art

[0002] SiO2 aerogel has a unique mesoporous structure and properties, and has a wide range of applications. Because of its excellent thermal insulation properties, it can be used as a super thermal insulation material in various fields, such as thermal insulation and sound insulation materials for building construction. Commonly used building insulation materials are mostly polymer foam materials such as polystyrene and polyurethane. The material size is relatively thick, which brings many problems to construction and later stability. In addition, polymer insulation materials are flammable and easy to cause fires. SiO2 aerogel can withstand high temperatures. Generally, at 800°C, there is no obvious change in structure and performance. It is a safe, energy-saving and environmentally friendly super thermal insulation material.

[0003] The mature preparation process of silica aerogel mainly uses methyl orthosilicate or ethyl orthosilicate as the silicon source and adopts supercritical drying process. However, due to the expensive raw materials for SiO2 aerogel preparation, the supercritical drying process is complicated, especially the technical difficulty of preparing high-quality aerogel, which hinders the industrial promotion of the product. Developing a production method with cheaper raw materials and simpler process will enable silica aerogel to develop more rapidly in the field of construction and create greater value.

[0004] Humus is a traditional rotten soil composed of a layer of mixture of plant matter and various organic wastes (such as kitchen waste). Humus accounts for more than 50% of the landfill stock, and the stock is huge and needs to be treated urgently. The material components in humus contain multiple elements such as Si, Al, Ca, and O; humus is rich in SiO2, Al2O3, CaO and other substances, among which the content of SiO2 is as high as 40-60%. After calcination and chemical treatment, it can be used as a low-quality silicon source, on the one hand to achieve harmless treatment of the increasing amount of humus, and on the other hand to increase the added value of the products prepared by humus. The main treatment methods of traditional humus are chemical leaching and landfilling with chelating agents, and secondly, as auxiliary materials to prepare high-quality bricks, cement and other building materials. There is no systematic solution for large-scale treatment. Therefore, how to use humus as raw material to prepare aerogel building insulation materials is a new technical exploration. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing an aerogel insulation board using humus as a raw material in view of the deficiencies in the prior art. The method has low raw material cost and simple process and is suitable for large-scale production of aerogel insulation materials for use in the construction field.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] The present invention first provides a method for preparing aerogel felt using humus as a raw material, comprising the following steps:

[0008] (2) Preparation of water glass

[0009] The humus soil after thermal desorption and screening is pretreated by an alkali melting method, the humus soil is mixed with sodium carbonate or sodium hydroxide, ball-milled, melted, and water-cooled to obtain water glass slag containing impurities, which is then dissolved with acid and solid-liquid separated to obtain a sodium silicate solution containing impurities, which is further filtered to obtain a water glass solution;

[0010] (2) Preparation of aerogel felt

[0011] a. Gel aging: directly add the separated filtrate to the alkaline solution to form silica sol, adjust the pH to 4.0-5.2; impregnate the mixed solution with glass fiber felt or pre-oxidized silk felt or foam, and let it stand to obtain wet gel;

[0012] b. Solvent replacement: Soak the wet gel in 60℃ hot water for 2-4 hours; take it out and soak it in 60℃ ethanol for 3-5 hours;

[0013] c. Hydrophobic modification: soak in 60℃ modifier for 2-4h;

[0014] d. Drying at normal pressure: Drying with nitrogen at 90-120°C under normal pressure to obtain aerogel felt;

[0015] Specifically, in step (1), the humus soil is desorbed for 2-5 hours at a temperature of 100-800°C.

[0016] Specifically, in step (1), the mass ratio of humus soil to sodium carbonate is 1:0.5-2.

[0017] Specifically, in step (1), the melting temperature is 900-1550° C., and the melting time is 50-300 min.

[0018] Specifically, the volume ratio of water glass to water in the filtrate after separation in step (2) is 1:0.5-3.

[0019] Specifically, the alkaline solution in step (2) is one of sodium hydroxide, potassium hydroxide, ammonia water and sodium carbonate with a mass fraction of 0.5-3 mol / L.

[0020] Specifically, the modifier in step (2) is one or a combination of hexamethyldisiloxane, hexamethyldisilazane or trimethylchlorosilane.

[0021] The present invention secondly provides an aerogel felt prepared by any one of the above methods.

[0022] The present invention thirdly provides a method for preparing an aerogel insulation board, comprising the following steps:

[0023] The aerogel felt is sewn and reinforced, and then holes are punched, pillars are filled in the holes, and then the upper and lower sides of the aerogel felt are covered with hard boards; the pillars are connected to the hard boards on the upper and lower sides with screws, and finally an aerogel insulation board is obtained.

[0024] The present invention fourthly provides an aerogel insulation board prepared by the above method.

[0025] The present invention uses humus as a raw material to prepare water glass, and further prepares aerogel felt and aerogel insulation board. The raw materials are cheap and abundant in source, overcoming the disadvantage of high preparation cost in the past. Moreover, the prepared aerogel material is a high-performance insulation material product, which increases the added value of humus, makes humus a resource, and turns waste into treasure. The humus can be used as a new type of high-quality energy-saving building material. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a flow chart for preparing the aerogel thermal insulation. DETAILED DESCRIPTION

[0027] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0028] The technical solution of the present invention mainly includes the following three parts: preparation of water glass, preparation of aerogel felt and preparation of aerogel insulation board. The specific preparation process is as follows: Figure 1 shown.

[0029] 1. Preparation of water glass

[0030] The humus soil after thermal desorption treatment is passed through a 0.5-2mm mesh screen to remove impurities with larger particles. The humus soil is pretreated by the alkali melting method, mixed with sodium carbonate in proportion, ball-milled to make its particle size less than 200 mesh, and then fully melted in a glass melting furnace to prepare a high-temperature glass liquid containing water glass with impurities. The high-temperature glass liquid is poured into water by water cooling to obtain water glass slag. The water glass slag is then dissolved with acid and solid-liquid separation is performed to obtain a sodium silicate solution containing impurities, which is further filtered to obtain a water glass solution;

[0031] The humus desorption treatment is carried out for 2-5 hours at a temperature of 100-800°C; the mass ratio of humus: sodium carbonate is 1:0.2-5; the acid is an inorganic acid such as hydrochloric acid, nitric acid, hydrofluoric acid, etc., and the acid concentration is 0.5-5 mol / L; the glass melting temperature is 900-1550°C, and the glass melting time is 50-300 minutes.

[0032] 2. Preparation of aerogel felt

[0033] a. Gel aging: directly add the separated filtrate to the alkaline solution to form silica sol, adjust the pH to 4.0-5.2; impregnate the mixed solution with glass fiber felt or pre-oxidized silk felt or foam, and let it stand to obtain wet gel;

[0034] b. Solvent replacement: Soak the wet gel in 60℃ hot water for 2-4 hours; take it out and soak it in 60℃ ethanol for 3-5 hours;

[0035] c. Hydrophobic modification: soak in 60℃ modifier for 2-4h;

[0036] d. Drying at normal pressure: Drying with nitrogen at 90-120°C under normal pressure to obtain aerogel felt;

[0037] The volume ratio of water glass to water in the separated filtrate is 1:0.5-3; the alkaline solution is one of sodium hydroxide, potassium hydroxide, ammonia water and sodium carbonate with a mass fraction of 0.5-3 mol / L; the modifier is one of hexamethyldisiloxane, hexamethyldisilazane and trimethylchlorosilane or a combination of several thereof.

[0038] 3. Preparation of aerogel insulation board

[0039] The aerogel felt is sewn and reinforced, and then holes are punched, pillars are filled in the holes, and then the upper and lower sides of the aerogel felt are covered with hard boards; the pillars are connected to the hard boards on the upper and lower sides with screws, and finally an aerogel insulation board is obtained.

[0040] Example 1

[0041] 1. Preparation of water glass

[0042] The humus soil was treated with a thermal desorption device for 4 hours, and the desorption temperature was set at 100°C to remove moisture, organic matter and some metal volatilization in the humus soil. After the pretreated humus soil was passed through a 0.5mm mesh sieve, NaOH additive was added, and the mixture was mixed in a mass ratio of humus soil: sodium carbonate = 1:2, ball milled for 2 hours, fully melted at a temperature of 1000°C for 90 minutes, and then poured into water for water cooling to obtain glass slag. The glass slag was taken out from the water cooling, and 1.5mol / L hydrochloric acid was added to the glass slag and stirred to dissolve the glass slag. Finally, solid-liquid phase separation was performed to separate the liquid phase, and the water glass solution was obtained after further filtration.

[0043] 2. Preparation of aerogel felt

[0044] a. Gel aging: The volume ratio of water glass to water in the separated filtrate is 1:3. 1 mol / L KOH solution is directly added to the water glass aqueous solution to form silica sol, and the pH is adjusted to 4.5; the mixed solution is impregnated with the pre-oxidized silk felt and allowed to stand to obtain a wet gel;

[0045] b. Solvent replacement: Soak the wet gel in 60℃ hot water for 4 hours; take it out and soak it in 60℃ ethanol for 4 hours;

[0046] c. Hydrophobic modification: soak in hexamethyldisiloxane at 60℃ for 3h;

[0047] d. Drying at normal pressure: Drying with nitrogen at 120°C under normal pressure to obtain aerogel felt.

[0048] 3. Preparation of aerogel insulation board

[0049] The aerogel felt is sewn and reinforced, and then holes are punched, pillars are filled in the holes, and then the upper and lower sides of the aerogel felt are covered with hard boards; the pillars are connected to the hard boards on the upper and lower sides with screws, and finally an aerogel insulation board is obtained.

[0050] Example 2

[0051] 1. Preparation of water glass

[0052] The humus soil was treated with a thermal desorption device for 2 hours, and the desorption temperature was set at 400°C to remove moisture, organic matter and some metal volatilization in the humus soil. After the pretreated humus soil was passed through a 2mm mesh, Na2CO3 additive was added, and the mixture was mixed in a mass ratio of humus soil: sodium carbonate = 1:4, ball milled for 3 hours, fully melted at a temperature of 1000°C for 120 minutes, and then poured into water for water cooling to obtain glass slag. The glass slag was taken out from the water cooling, and 0.5 mol / L hydrochloric acid was added to the glass slag and stirred to dissolve the glass slag. Finally, solid-liquid phase separation was performed to separate the liquid phase, and the water glass solution was obtained after further filtration.

[0053] 2. Preparation of aerogel felt

[0054] a. Gel aging: The volume ratio of water glass to water in the separated filtrate is 2:1. 2 mol / L ammonia water is directly added to the water glass aqueous solution to form silica sol, and the pH is adjusted to 5.0; the mixed solution is impregnated with foam and allowed to stand to obtain wet gel;

[0055] b. Solvent replacement: Soak the wet gel in 60℃ hot water for 4 hours; take it out and soak it in 60℃ ethanol for 5 hours;

[0056] c. Hydrophobic modification: soak in hexamethyldisilazane at 60℃ for 2h;

[0057] d. Drying at normal pressure: Drying with nitrogen at 90°C under normal pressure to obtain aerogel felt.

[0058] 3. Preparation of aerogel insulation board

[0059] The aerogel felt is sewn and reinforced, and then holes are punched, pillars are filled in the holes, and then the upper and lower sides of the aerogel felt are covered with hard boards; the pillars are connected to the hard boards on the upper and lower sides with screws, and finally an aerogel insulation board is obtained.

[0060] Example 3

[0061] 1. Preparation of water glass

[0062] The humus soil was treated with a thermal desorption device for 5 hours, and the desorption temperature was set at 800℃ to remove moisture, organic matter and some metal volatilization in the humus soil. After the pretreated humus soil was passed through a 0.5mm mesh screen, Na2CO3 additive was added, and the mixture was mixed in a mass ratio of humus soil: sodium carbonate = 5:1, ball milled for 3 hours, fully melted at a temperature of 1550℃ for 300 minutes, and poured into water for water cooling to obtain glass slag. The glass slag was taken out from the water cooling, and a mixed acid of 5mol / L nitric acid and 0.5mol / L hydrofluoric acid was added to the glass slag and stirred to dissolve the glass slag. Finally, after calcination, solid-liquid phase separation was performed to separate the liquid phase, and the water glass solution was obtained after further filtration.

[0063] 2. Preparation of aerogel felt

[0064] a. Gel aging: The volume ratio of water glass to water in the separated filtrate is 2:3. 0.5 mol / L NaOH solution is directly added to the water glass aqueous solution to form silica sol, and the pH is adjusted to 5.2; the mixed solution is impregnated with glass fiber felt and allowed to stand to obtain wet gel;

[0065] b. Solvent replacement: Soak the wet gel in 60℃ hot water for 2 hours; take it out and soak it in 60℃ ethanol for 5 hours;

[0066] c. Hydrophobic modification: soak in 60℃ trimethylchlorosilane for 3h;

[0067] d. Drying at normal pressure: Drying with nitrogen at 90-120°C under normal pressure to obtain aerogel felt.

[0068] 3. Preparation of aerogel insulation board

[0069] The aerogel felt is sewn and reinforced, and then holes are punched, pillars are filled in the holes, and then the upper and lower sides of the aerogel felt are covered with hard boards; the pillars are connected to the hard boards on the upper and lower sides with screws, and finally an aerogel insulation board is obtained.

[0070] Example 4

[0071] 1. Preparation of water glass

[0072] The humus soil was treated with a thermal desorption device for 2 hours, and the desorption temperature was set at 100°C to remove moisture, organic matter and some metal volatilization in the humus soil. After the pretreated humus soil was passed through a 2mm mesh, sodium hydroxide was added as an auxiliary agent, and the mixture was mixed in a mass ratio of humus soil: sodium hydroxide = 1:5, ball milled for 1 hour, fully melted at a temperature of 900°C for 50 minutes, and poured into water for water cooling to obtain glass slag. The glass slag was taken out from the water cooling, and 0.5 mol / L nitric acid was added to the glass slag and stirred to dissolve the glass slag. Finally, after calcination, solid-liquid phase separation was performed to separate the liquid phase, and the water glass solution was obtained after further filtration.

[0073] 2. Preparation of aerogel felt

[0074] a. Gel aging: The volume ratio of water glass to water in the separated filtrate is 1:1. 3 mol / L sodium carbonate solution is directly added to the water glass aqueous solution to form silica sol and the pH is adjusted to 4.6. The mixed solution is impregnated with glass fiber felt and allowed to stand to obtain wet gel;

[0075] b. Solvent replacement: Soak the wet gel in 60℃ hot water for 3 hours; take it out and soak it in 60℃ ethanol for 3 hours;

[0076] c. Hydrophobic modification: soak in a mixed modifier of hexamethyldisilazane and trimethylchlorosilane at 60°C for 4 hours;

[0077] d. Drying at normal pressure: Drying with nitrogen at 100°C under normal pressure to obtain aerogel felt.

[0078] 3. Preparation of aerogel insulation board

[0079] The aerogel felt is sewn and reinforced, and then holes are punched, pillars are filled in the holes, and then the upper and lower sides of the aerogel felt are covered with hard boards; the pillars are connected to the hard boards on the upper and lower sides with screws, and finally an aerogel insulation board is obtained.

Claims

1. A method for preparing aerogel felt using humus as raw material, It is characterized in that The following steps are involved: (1) Preparation of water glass The humus soil after thermal desorption and screening is pretreated by an alkali melting method, the humus soil is mixed with sodium carbonate, ball-milled, melted, and water-cooled to obtain water glass slag containing impurities, which is then dissolved with acid and solid-liquid separated to obtain a sodium silicate solution containing impurities, which is further filtered to obtain a water glass solution; (2) Preparation of aerogel felt a. Gel aging: directly add the separated filtrate to the alkaline solution to form silica sol, adjust the pH to 4.0-5.2; impregnate the mixed solution with glass fiber felt or pre-oxidized silk felt or foam, and let it stand to obtain wet gel; b. Solvent replacement: Soak the wet gel in 60℃ hot water for 2-4 hours; take it out and soak it in 60℃ ethanol for 3-5 hours; c. Hydrophobic modification: soak in 60℃ modifier for 2-4h; d. Drying at normal pressure: Drying with nitrogen at 90-120°C under normal pressure to obtain aerogel felt; In step (1), the humus soil is desorbed for 2-5 hours at a temperature of 100-800°C; In the step (1), the mass ratio of humus soil to sodium carbonate is 1:0.2-5; In the step (1), the melting temperature is 900-1550° C. and the melting time is 50-300 min.

2. The method for preparing aerogel felt using humus as raw material according to claim 1, Features: The volume ratio of water glass to water in the filtrate after separation in step (2) is 1:0.5-3.

3. The method for preparing aerogel felt using humus as raw material according to claim 1, Features: The alkaline solution in step (2) is one of sodium hydroxide, potassium hydroxide, ammonia water and sodium carbonate with a mass fraction of 0.5-3 mol / L.

4. The method for preparing aerogel felt using humus as raw material according to claim 1, Features: In the step (2), the modifier is one or a combination of hexamethyldisiloxane, hexamethyldisilazane or trimethylchlorosilane.

5. An aerogel felt prepared by the method according to any one of claims 1 to 4.

6. A method for preparing an aerogel insulation board, It is characterized in that The following steps are involved: After sewing and reinforcing the aerogel felt described in claim 5, holes are punched, pillars are filled in the holes, and then the upper and lower sides of the aerogel felt are covered with hard boards; the pillars are connected to the hard boards on the upper and lower sides with screws to finally obtain an aerogel insulation board.

7. An aerogel insulation board prepared by the method of claim 6.

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