Silica aerogel / aluminum silicate fiber paper composite and preparation method

Abstract

The application discloses a silica aerogel / aluminum silicate fiber paper composite material and a preparation method thereof. In a silica sol process, a solute containing a phytic acid derivative is added to the silica sol, and a mixed system is obtained after sufficient mixing. The silica aerogel / aluminum silicate fiber paper composite material is prepared through normal-pressure drying, the heavy metal adsorption performance of the prepared composite material is greatly improved, and the adhesion of the aerogel on the surface of the fiber paper can also be improved. In the scheme, the normal-pressure drying is adopted, compared with the supercritical CO2 drying, the large and expensive equipment is not needed, the operation is simple, and the large-scale popularization in the later period is facilitated. Compared with the aluminum silicate fiber paper, the high-temperature use performance of the composite material is improved, and the replacement rate of the thermal insulation material is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of thermal insulation, in particular to a silica aerogel / aluminum silicate fiber paper composite material and a preparation method thereof. BACKGROUND

[0002] Traditional aluminum silicate fiber paper is a commonly used thermal insulation material, which is mainly processed by aluminum silicate fiber, inorganic binder and organic binder, and is often used in industrial production process. However, the substances directly contacting with the aluminum silicate fiber paper in the industrial production process, such as ceramic clay, often contain a large amount of heavy metal ions, which are highly toxic. The traditional aluminum silicate fiber paper has a great potential health risk to the daily operation of workers.

[0003] How to prepare an aluminum silicate fiber paper composite material which can effectively adsorb heavy metal ions and is suitable for industrialization is the direction to be explored by the present application. SUMMARY

[0004] The main purpose of the present application is to provide a silica aerogel / aluminum silicate fiber paper composite material which can effectively adsorb heavy metal ions and is suitable for industrialization, and a preparation method thereof, aiming at solving the potential health risk problem of the substances contacting with the aluminum silicate fiber paper in the background art, which often have strong heavy metal toxicity and affect the daily operation of workers in industrial production.

[0005] To achieve the above-mentioned purpose, the present application provides a silica aerogel / aluminum silicate fiber paper composite material and a preparation method thereof, comprising the following preparation steps:

[0006] S1, mixing tetraethyl orthosilicate, solvent and deionized water to prepare a silicon mixed solution, adjusting the pH value of the silicon mixed solution to 5-6 to obtain a silica sol;

[0007] S2, introducing a phytic acid derivative solute into the silica sol, and fully mixing to obtain a mixed system;

[0008] S3, immersing the aluminum silicate fiber paper into the mixed system, adding an aging liquid at room temperature under normal pressure to age and gel by standing;

[0009] S4, drying under normal pressure to obtain a silica aerogel / aluminum silicate fiber paper composite material.

[0010] Currently, due to the relatively cheap and abundant resources of Si resources, it is suitable for industrialization, and most of the aerogel materials are still mainly SiO2 aerogel, and the scheme uses aluminum silicate fiber paper as the substrate to prepare silica aerogel composite material, and the scheme adds phytic acid derivatives in the gel process, and the high negative charge phytic acid derivatives have strong complexing ability for various metal ions, and the adsorption of metal ions is completed, the silica aerogel / aluminum silicate fiber paper composite material prepared by the scheme greatly improves the heavy metal adsorption performance of the prepared composite material, and can also improve the adhesion of the aerogel on the surface of the fiber paper. In the scheme, the drying method of normal pressure drying is used, compared with supercritical CO2 drying, without using large and expensive equipment, the operation is simple, and it is conducive to large-scale promotion in the later period. Compared with aluminum silicate fiber paper, the composite material improves the high temperature use performance, and the existing aluminum silicate fiber paper has limited heat resistance due to the limited heat resistance of the organic binder, and is usually only suitable for use below 800 DEG C. In the industrial production of ceramics, the working temperature is often above 1000 DEG C, so that the aluminum silicate fiber paper is quickly consumed.

[0011] Preferably, in step S2, the molar ratio of tetraethyl orthosilicate in the silica sol to the phytic acid derivative solute is 1:0.01-0.2, which further improves the heavy metal adsorption performance, and further preferably, in step S2, the molar ratio of tetraethyl orthosilicate in the silica sol to the phytic acid derivative solute is 1:0.03-0.1. The heavy metal adsorption performance of the silica aerogel / aluminum silicate fiber paper composite material prepared by the preferred molar ratio is relatively excellent, and the formation of the porous structure of the aerogel is not affected by the excessive molar ratio of the phytic acid derivative solute, which reduces the number of pores and further reduces the heavy metal adsorption rate.

[0012] In a preferred embodiment, in step S2, the phytic acid derivative solute is at least one of phytic acid, calcium phytate, sodium phytate, zinc phytate, barium phytate, and potassium phytate.

[0013] In a preferred embodiment, in step S1, the molar ratio of tetraethyl orthosilicate, solvent, and water is 1-5:12:9, and further preferably, in step S1, the molar ratio of tetraethyl orthosilicate, solvent, and water is 3-5:12:9. In the preferred molar ratio range of the scheme, the linear shrinkage rate of the obtained composite material is more optimal, which helps to reduce the replacement rate and save the loss of thermal insulation materials.

[0014] Preferably, the solvent is at least one of methanol, ethanol, propanol, isopropanol, n-butanol, tert-butanol, sec-butanol, pentanol and its isomers, hexanol and its isomers, and acetone.

[0015] In one specific embodiment, the drying temperature of the drying process in step S4 is 50-100℃, and the drying time is 48-72h.

[0016] In one specific embodiment, in step S3, the aging time is 12-60h, and the standing gel time is 0.5-3h.

[0017] In one specific embodiment, in step S3, the aging liquid is at least one of methanol, ethanol, n-hexane, propanol and acetone. Different aging liquids have different volatilization abilities at the same temperature, which can affect the progress of the gelation and aging processes. If the volatilization is too fast, the structure is not stable enough, and the composite material structure is brittle. If the volatilization is too slow, the material is immersed in the aging liquid for a long time, which can also reduce the stability of the material. The easy-volatilization aging liquid can accelerate the progress of the gelation and aging processes, and improve the structural strength and stability of the silica aerogel in the obtained composite material.

[0018] The application also provides a silica aerogel / aluminum silicate fiber paper composite material prepared by the preparation method of the silica aerogel / aluminum silicate fiber paper composite material according to any one of the above-mentioned schemes. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments or prior art of the present application, the drawings needed in the embodiment or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other related drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 SEM photo of the present application comparative example 1 after 3h at 1000℃;

[0021] Figure 2 SEM photo of the present application example 1 after 3h at 1000℃;

[0022] Figure 3 SEM photo of the present application comparative example 2 after 3h at 1000℃.

[0023] The implementation, functional characteristics and advantages of the present application will be further described with reference to the embodiments and the drawings. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the protection scope of the present application. In addition, the technical solutions of various embodiments can be combined with each other, but it should be considered that the combination of the technical solutions does not exist and is not within the protection scope of the present application when the combination of the technical solutions appears contradictory or unachievable on the basis that a person of ordinary skill in the art can achieve.

[0025] Embodiment 1

[0026] Ethyl orthosilicate, ethanol and deionized water were added into a beaker in a molar ratio of 1:4:3, and 0.1 mol / L hydrochloric acid solution was slowly added dropwise to adjust the pH to 5-6 to form a silica sol, the molar ratio of ethyl orthosilicate to the phytic acid derivative-containing substance was 1:0.03, the phytic acid derivative-containing substance was phytic acid, and the mixture was stirred until it became homogeneous.

[0027] The aluminum silicate fiber paper with a length of 50 mm, a width of 20 mm and a thickness of 0.5 mm was soaked in the silica sol system, and after standing for 1 h, the product was gently taken out and placed flat on a culture dish. Proper n-hexane was used as an aging liquid to age at room temperature under normal pressure for 12 h, and heating was performed at 60 DEG C under normal pressure for 48 h, and finally the silica aerogel / aluminum silicate fiber paper composite material dried under normal pressure was obtained.

[0028] Embodiment 2-1

[0029] Compared with Embodiment 1, the difference of the present embodiment lies in that the molar ratio of ethyl orthosilicate, ethanol and deionized water is 1:12:9.

[0030] Embodiment 2-2

[0031] Compared with Embodiment 2-1, the difference of the present embodiment lies in that the molar ratio of ethyl orthosilicate, ethanol and deionized water is 5:12:9.

[0032] Embodiment 3-1

[0033] Compared with Embodiment 1, the difference of the present embodiment lies in that the phytic acid derivative-containing substance is a composite of calcium phytate and potassium phytate, and the molar ratio of calcium phytate to potassium phytate is 1:1, which is as follows:

[0034] Ethyl orthosilicate, ethanol, deionized water were added into a beaker in a molar ratio of 1 :4:3, 0.1 mol / L hydrochloric acid solution was slowly added to adjust the pH to 5-6 to form a silica sol, the molar ratio of ethyl orthosilicate to the phytic acid derivative was 1:0.01, the phytic acid derivative was phytic acid, and the mixture was stirred until it became homogeneous.

[0035] The aluminum silicate fiber paper with a length of 50 mm, a width of 20 mm, and a thickness of 0.5 mm was soaked in the silica sol system, and was placed for 1 h, and was gently taken out after the product was basically shaped, and was placed flat in a culture dish, and was aged at room temperature for 12 h with proper n-hexane as an aging liquid, and was heated at 60°C under normal pressure for 48 h, and finally the silica aerogel / aluminum silicate fiber paper composite material dried under normal pressure was obtained.

[0036] Example 3-2

[0037] Compared with Example 3-1, the difference of the present example is that the molar ratio of ethyl orthosilicate to the phytic acid derivative is 1:0.2.

[0038] Example 3-3

[0039] Compared with Example 3-1, the difference of the present example is that the molar ratio of ethyl orthosilicate to the phytic acid derivative is 1:0.005.

[0040] Example 4-1

[0041] Compared with Example 1, the difference of the present example is that the molar ratio of ethyl orthosilicate to the phytic acid derivative is 1:0.01, and the specific process is as follows:

[0042] Ethyl orthosilicate, ethanol, deionized water were added into a beaker in a molar ratio of 1 :4:3, 0.1 mol / L hydrochloric acid solution was slowly added to adjust the pH to 5-6 to form a silica sol, the molar ratio of ethyl orthosilicate to the phytic acid derivative was 1:0.01, the phytic acid derivative was phytic acid, and the mixture was stirred until it became homogeneous.

[0043] The aluminum silicate fiber paper with a length of 50 mm, a width of 20 mm, and a thickness of 0.5 mm was soaked in the silica sol system, and was placed for 1 h, and was gently taken out after the product was basically shaped, and was placed flat in a culture dish, and was aged at room temperature for 12 h with proper n-hexane as an aging liquid, and was heated at 60°C under normal pressure for 48 h, and finally the silica aerogel / aluminum silicate fiber paper composite material dried under normal pressure was obtained.

[0044] Example 4-2

[0045] The difference between this example and Example 4-1 is that the molar ratio of tetraethyl orthosilicate to the phytic acid derivative-containing is 1:0.1.

[0046] Comparative Example 1

[0047] Aluminum silicate fiber paper with a length of 50 mm, a width of 20 mm, and a thickness of 0.5 mm.

[0048] Comparative Example 2

[0049] The difference between this example and Example 1 is that no phytic acid derivative-containing is introduced before the gel stage in the preparation step, and the silica aerogel / aluminum silicate fiber paper composite is prepared using the same steps, as follows:

[0050] Tetraethyl orthosilicate, ethanol, and deionized water were added to a beaker in a molar ratio of 1:4:3, and 0.1 mol / L hydrochloric acid solution was slowly added dropwise to adjust the pH to 5-6, and a homogeneous silica sol state was formed by stirring.

[0051] Aluminum silicate fiber paper with a length of 50 mm, a width of 20 mm, and a thickness of 0.5 mm was immersed in the silica sol system, and after 1 h of standing, the product was gently removed and placed flat on a petri dish. Appropriate n-hexane was used as an aging liquid for 12 h of normal pressure room temperature aging, and 48 h of heating at 60°C under normal pressure, and a normal pressure dried silica aerogel / aluminum silicate fiber paper composite was finally obtained.

[0052] Comparative Example 3

[0053] The difference between this example and Example 1 is that the molar ratio of tetraethyl orthosilicate to the phytic acid derivative-containing is 1:0.005, as follows:

[0054] Tetraethyl orthosilicate, ethanol, and deionized water were added to a beaker in a molar ratio of 1:4:3, and 0.1 mol / L hydrochloric acid solution was slowly added dropwise to adjust the pH to 5-6, and a homogeneous silica sol state was formed by stirring.

[0055] Aluminum silicate fiber paper with a length of 50 mm, a width of 20 mm, and a thickness of 0.5 mm was immersed in the silica sol system, and after 1 h of standing, the product was gently removed and placed flat on a petri dish. Appropriate n-hexane was used as an aging liquid for 12 h of normal pressure room temperature aging, and 48 h of heating at 60°C under normal pressure, and a normal pressure dried silica aerogel / aluminum silicate fiber paper composite was finally obtained.

[0056] Comparative Example 4

[0057] The difference between the present comparative example and Example 1 is that the molar ratio of tetraethyl orthosilicate to the phytate derivative-containing is 1:0.2, as follows:

[0058] Tetraethyl orthosilicate, ethanol and deionized water were added into a beaker in a molar ratio of 1:4:3, and a 0.1 mol / L hydrochloric acid solution was slowly added to adjust the pH to 5-6 to form a silica sol. The molar ratio of tetraethyl orthosilicate to the phytate derivative-containing was 1:0.2, and the phytate derivative-containing was phytic acid. The mixture was stirred until it became homogeneous.

[0059] An aluminum silicate fiber paper with a length of 50 mm, a width of 20 mm, and a thickness of 0.5 mm was immersed in the silica sol system, and after standing for 1 h, the product was gently removed and placed flat in a culture dish. Appropriate n-hexane was used as an aging liquid for normal pressure room temperature aging for 12 h, and heating at normal pressure at 60°C for 48 h. Finally, a normal pressure dried silica aerogel / aluminum silicate fiber paper composite material was obtained.

[0060] Effect verification method:

[0061] 1. Heavy metal adsorption performance determination:

[0062] The prepared flame-retardant and heavy metal adsorbing aerogel / aluminum silicate fiber paper was added to a multi-cation solution with an appropriate concentration, and an inductively coupled plasma (ICP-OES) device was used to test the ion residual concentration after 1, 2, 5, 8, 15, and 30 min to calculate the ion interception rate. The multi-cation solution was selected from Ag + , Ba 2+ , Cd 2+ , Co 2+ , Cr 2+ , Fe 2+ , Fe 3+ , Mn 2+ , Ni 2+ , Pb 2+ , and Zn 2+ , and the concentration of the multi-cation solution was 20 mg / L.

[0063] In the present scheme, when the ion interception rate is <50%, the heavy metal adsorption performance is unqualified; when 50%≤ion interception rate<75%, the heavy metal adsorption performance is qualified; when 75%≤ion interception rate<85%, the heavy metal adsorption performance is good; and when the ion interception rate is ≥85%, the heavy metal adsorption performance is excellent.

[0064] 2. High temperature use performance determination:

[0065] In the present scheme, the high-temperature service performance is evaluated by two items of thermal conductivity and linear shrinkage. The thermal conductivity is inversely proportional to the heat insulation capacity of the heat insulation material at the temperature, and the linear shrinkage is proportional to the replacement rate of the heat insulation material.

[0066] In the present scheme, the thermal conductivity is determined at 300℃, 600℃, 800℃ and 1000℃ according to YB / T41302005 "Test Method for Thermal Conductivity of Refractory Materials (Water Flow Plate Method)", and the linear shrinkage is determined after 3h at 1000℃.

[0067] Heavy metal adsorption performance test 1: The composite material obtained in Example 1 was subjected to heavy metal adsorption performance test, and the results are as follows:

[0068] Metal ion / retention (%) Example 1 Ag + ]]> 80％ Ba 2+ ]]> 92％ Cd 2+ ]] 86％ Co 2+ ]]> 88％ Cr 2+ ]] 94％ Fe 2+ ]] 85％ Fe 3+ ]] 85％ Mn 2+ ]] 86％ Ni 2+ ]]> 88％ Pb 2+ ]]> 87％ Zn 2+ ]] 94％

[0069] According to the data in the above table, the composite material obtained in the present example has a metal ion interception rate of 80-94% in Ag + , Ba 2+ , Cd 2+ , Co 2+ , Cr 2+ , Fe 2+ , Fe 3+ , Mn 2+ , Ni 2+ , Pb 2+ and Zn 2+ , and the heavy metal adsorption performance is excellent.

[0070] Heavy metal adsorption performance test 2: The materials obtained in Example 1, Comparative Example 1 and Comparative Example 2 were subjected to heavy metal adsorption test, and the results are as follows:

[0071]

[0072] As can be seen from the data in the above table, the heavy metal ion interception rate of the silica aerogel / aluminum silicate fiber paper composite material containing phytic acid derivatives introduced therein is significantly higher than that of the aluminum silicate fiber paper and the silica aerogel / aluminum silicate fiber paper composite material without phytic acid derivatives introduced therein.

[0073] Heavy metal adsorption performance test 3: The composite materials obtained in Example 1, Example 4-1, Example 4-2, Comparative Example 3 and Comparative Example 4 were subjected to heavy metal adsorption test, and the results are as follows:

[0074]

[0075] From the data in the above table, it can be seen that when the molar ratio of tetraethyl orthosilicate to the phytic acid derivative is 1:0.05, the heavy metal adsorption performance is unqualified, when the molar ratio of tetraethyl orthosilicate to the phytic acid derivative is 1:0.2, the heavy metal adsorption performance does not increase but decreases, which is presumably because the increase of the content of the phytic acid derivative affects the formation of the aerogel porous structure, resulting in a decrease in the number of pores, and further resulting in a decrease in the heavy metal adsorption performance, when the molar ratio of tetraethyl orthosilicate to the phytic acid derivative is 1:0.03-0.1, the heavy metal adsorption performance is relatively excellent, and the molar ratio of the phytic acid derivative solute is not too high to affect the formation of the aerogel porous structure, and further resulting in a decrease in the heavy metal adsorption rate.

[0076] High-temperature use performance test 1: The materials obtained from Example 1, Comparative Example 1 and Comparative Example 2 were subjected to thermal conductivity and linear shrinkage rate determination, and the results are as follows:

[0077]

[0078] From the above table, it can be seen that:

[0079] 1. In this group of data, the thermal conductivity is between 0.045-0.104 W / (m·K), and the thermal conductivity at each determination temperature is not much different;

[0080] 2. The linear shrinkage rates of Example 1 and Comparative Example 2 after 3h at 1000℃ are both within 10%, which is significantly better than that of Comparative Example 1.

[0081] 3. In general, the high-temperature use performance of the silica aerogel / aluminum silicate fiber paper composite materials in Example 1 and Comparative Example 2 at 1000℃ is significantly better than that of the aluminum silicate fiber paper in Comparative Example 1.

[0082] In addition, from Figure 1 (the SEM photo of Comparative Example 1 after 3h at 1000℃) it can be seen that the aluminum silicate fiber paper of Comparative Example 1 has collapsed and is fluffy at high temperature 1000℃; from Figure 2 (the SEM photo of Example 1 after 3h at 1000℃) it can be seen that the surface of the composite material of Example 1 is obviously rough, which is actually the attachment of silica on the surface, but it has not collapsed at high temperature 1000℃ for 3h; from Figure 3 (the SEM photo of Comparative Example 2 after 3h at 1000℃) it can be seen that although the composite material of Comparative Example 2 has not collapsed at high temperature, the structure of the silica aerogel is in large blocks, which will lead to a decrease in the toughness and brittleness of the composite fiber paper, which indicates that the addition of the phytic acid derivative can improve the attachment ability of the aerogel on the fiber surface, which is presumably because the addition of the phytic acid derivative promotes the hydrolysis of tetraethyl orthosilicate, making it more evenly dispersed on the fiber surface.

[0083] High temperature use performance test 2: the composite material obtained from example 1, example 2-1, example 2-2, example 3-1~example 3-3, example 4-1~example 4-2 is carried out high temperature use performance test, and the results are as follows:

[0084]

[0085] It can be known from the above table that:

[0086] 1. In the group of data, the thermal conductivity is between 0.044~0.108 W / (m·K), and the thermal conductivity at each test temperature is not much different;

[0087] 2. In the group of data, the linear shrinkage is between 6.8%~10.8%, compared with example 1, example 2-1, example 2-2, it can be seen that as the molar ratio of tetraethyl orthosilicate in the system of tetraethyl orthosilicate: ethanol: deionized water increases, the linear shrinkage of the obtained composite material will also decrease. When the molar ratio of tetraethyl orthosilicate: ethanol: deionized water is 3~5:12:9, it has a more optimal linear shrinkage;

[0088] Comparing example 1, example 3-1~example 3-3 and example 4.1~example 4-2, it generally presents that as the molar ratio of the phytic acid derivative in the molar ratio of tetraethyl orthosilicate and the phytic acid derivative is higher, the linear shrinkage will increase;

[0089] 3. The silica aerogel / aluminum silicate fiber paper composite material in example 2-2 has the best high temperature use performance.

[0090] The above only describes the preferred embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent structural transformation made according to the content of the present application, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. Use of a silica aerogel / alumina silicate fibrous paper composite for adsorbing heavy metal ions, characterized in that, The silica aerogel / aluminum silicate fiber paper composite material comprises the following preparation steps: S1, mixing tetraethyl orthosilicate, solvent and deionized water to prepare a silicon mixture, adjusting the pH value of the silicon mixture to 5-6 to obtain a silica sol; S2, introducing a phytic acid derivative-containing solute into the silica sol, the phytic acid derivative-containing solute being at least one of phytic acid, calcium phytate, sodium phytate, zinc phytate, barium phytate and potassium phytate, and fully mixing to obtain a mixed system; the molar ratio of the tetraethyl orthosilicate in the silica sol to the phytic acid derivative-containing solute is 1:0.03-0.1 S3, immersing the aluminum silicate fiber paper in the mixed system, adding an aging liquid at normal pressure and room temperature to age and gel by standing; S4, drying at normal pressure to obtain the silica aerogel / aluminum silicate fiber paper composite material.

2. The application of the silica aerogel / aluminosilicate fiber paper composite material as described in claim 1 for adsorbing heavy metal ions, characterized in that, In step S1, the molar ratio of the tetraethyl orthosilicate, solvent and water is 1-5:12:

9.

3. Use of a silica aerogel / aluminum silicate fibrous paper composite material according to claim 2 for adsorbing heavy metal ions, characterized in that, In step S1, the molar ratio of the tetraethyl orthosilicate, solvent and water is 3-5:12:

9.

4. The application of the silica aerogel / aluminosilicate fiber paper composite material for adsorbing heavy metal ions as described in claim 2, characterized in that, In step S1, the solvent is at least one of methanol, ethanol, propanol, isopropanol, n-butanol, tert-butanol, sec-butanol, pentanol and its isomers, hexanol and its isomers, and acetone.

5. The application of the silica aerogel / aluminosilicate fiber paper composite material as described in claim 2 for adsorbing heavy metal ions, characterized in that, In step S3, the aging liquid is at least one of methanol, ethanol, n-hexane, propanol and acetone, the aging time is 12-60h, and the gel standing time is 0.5-3h.

6. The application of the silica aerogel / aluminosilicate fiber paper composite material as described in claim 2 for adsorbing heavy metal ions, characterized in that, In step S4, the drying temperature of the drying process is 50-100℃, and the drying time is 48-72h.

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