CN108484098B - Normal-pressure preparation method of silicon dioxide/attapulgite fiber composite aerogel - Google Patents
Normal-pressure preparation method of silicon dioxide/attapulgite fiber composite aerogel Download PDFInfo
- Publication number
- CN108484098B CN108484098B CN201810688339.3A CN201810688339A CN108484098B CN 108484098 B CN108484098 B CN 108484098B CN 201810688339 A CN201810688339 A CN 201810688339A CN 108484098 B CN108484098 B CN 108484098B
- Authority
- CN
- China
- Prior art keywords
- fiber composite
- attapulgite
- silicon dioxide
- attapulgite fiber
- silica
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B30/00—Compositions for artificial stone, not containing binders
- C04B30/02—Compositions for artificial stone, not containing binders containing fibrous materials
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
- C04B38/02—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by adding chemical blowing agents
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/20—Mortars, concrete or artificial stone characterised by specific physical values for the density
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/30—Mortars, concrete or artificial stone characterised by specific physical values for heat transfer properties such as thermal insulation values, e.g. R-values
- C04B2201/32—Mortars, concrete or artificial stone characterised by specific physical values for heat transfer properties such as thermal insulation values, e.g. R-values for the thermal conductivity, e.g. K-factors
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Silicon Compounds (AREA)
Abstract
The invention discloses a normal pressure preparation method of silicon dioxide/attapulgite fiber composite aerogel, which comprises the following steps: uniformly mixing an organic silicon precursor, absolute ethyl alcohol and deionized water, and adding an acidic catalyst until the pH value is 2-3 to obtain silicon dioxide sol; adding attapulgite fibers, uniformly mixing, adjusting the pH to 6-8 by using a carbonate/ammonia water mixed solution, transferring to a mold, standing to obtain silicon dioxide/attapulgite fiber composite hydrogel, and aging; taking out the silicon dioxide/attapulgite fiber composite hydrogel from the mold, and soaking the hydrogel in a sodium bicarbonate aqueous solution for solvent replacement; and fully drying after replacement to obtain the hydrophilic silicon dioxide/attapulgite fiber composite aerogel. The method provided by the invention overcomes the problem that the aerogel prepared by a common normal pressure drying method has powder and small fragments, and realizes the normal pressure preparation of the whole aerogel with hydrophobic or hydrophilic characteristics.
Description
Technical Field
The invention relates to preparation of silicon dioxide aerogel, in particular to a normal-pressure preparation method of silicon dioxide/attapulgite fiber composite aerogel.
Background
Silicon dioxide (SiO)2) Aerogel is a nanoporous amorphous solid state material with a spatial network structure composed of colloidal particles. The porosity of the material can reach 80-99.9%, and the pore size and the skeleton particle size are respectively 5-70 nm and 1About 50 nm. Silica aerogels have many unique properties, such as high specific surface area, high porosity, high thermal insulation, low density, and the like. Because the silicon dioxide aerogel has the unique properties, the silicon dioxide aerogel has wide and huge application prospects in the fields of optics, heat insulation, acoustics, catalyst carriers, microelectronics, chemical engineering, aerospace and the like.
In the process of preparing silica aerogel, the key process is the drying process of the wet gel. Due to the existence of capillary force and the high water vapor pressure in the nano pores of the aerogel, the wet gel is easy to shrink and deform and crack in the drying process, and a complete silica aerogel block is difficult to obtain. Although the supercritical drying method, which is widely used in industry, can effectively prepare silica aerogel, the equipment used is expensive and complicated to operate, and tens to hundreds of atmospheric pressures are used, which causes great danger and makes continuous mass production difficult. In order to realize the atmospheric drying method for preparing the silica aerogel, the following methods are generally adopted: the method has the advantages of enhancing the skeleton strength of a gel network, enabling holes in the gel to be uniform through a chemical method, and reducing capillary force applied to the gel during drying through solvent replacement and surface modification.
However, the modification of the hydrophilic groups in the pores of the wet gel is greatly influenced by the concentration of the surface-modifying agent: the high concentration causes the reaction to be too fast, the pressure in the hole is too high, and the aerogel framework is cracked in the modification stage; the initial concentration of the modifying agent is reduced, and the concentration of the modifying agent is gradually reduced at the later stage of the reaction, so that the modification cannot be complete. Both of these conditions lead to cracking of the aerogel during drying, and only a granular aerogel mass can be obtained.
Meanwhile, because the mechanical properties of the pure silica aerogel are poor, glass fibers, aluminum silicate fibers and mullite fibers are generally adopted as reinforcing agents to improve the mechanical strength of the aerogel. Because high-alkali glass fiber and aluminum silicate refractory fiber materials are seriously damaged to human skin and respiratory system after being pulverized at high temperature, the materials are determined as CMR2 carcinogens by the REACH regulation in 2011 and are greatly limited in application of building heat insulation and the like. The natural fiber has the characteristics of environmental protection, low cost and the like, and becomes a hot research point for reinforcing aerogel materials in recent years.
For example, the silica aerogel with stable pores and a skeleton structure is prepared by drying sepiolite fibers as a reinforcing agent under normal pressure in the Chinese patent with the publication number of CN 105272143A. The Chinese patent with publication number CN105565774B adopts an amino-terminated agent to firstly carry out surface modification on halloysite to eliminate hydrophilic hydroxyl, then carries out framework reinforcement through dimethylformamide, and finally needs to carry out organic solvent replacement and carbon dioxide supercritical extraction to prepare the high-strength silica aerogel. The methods can prepare the aerogel with better heat insulation performance, but the silicon dioxide aerogel prepared by normal pressure drying is usually incompletely modified, the obtained aerogel is granular aerogel fragments, and the whole aerogel is difficult to prepare. Meanwhile, the supercritical method has expensive equipment and complex operation, and is difficult to carry out continuous large-scale production.
Disclosure of Invention
The invention aims to provide a normal-pressure preparation method of silicon dioxide/attapulgite fiber composite aerogel, which overcomes the problem that powder and small fragments of aerogel occur in the preparation of general normal-pressure drying methods, and realizes the preparation of silicon dioxide/attapulgite fiber composite monolithic aerogel with hydrophobic or hydrophilic characteristics under normal pressure.
The invention adopts the following technical scheme:
a normal pressure preparation method of silicon dioxide/attapulgite fiber composite aerogel comprises the following steps:
(1) uniformly mixing an organic silicon precursor, absolute ethyl alcohol and deionized water, adding an acidic catalyst until the pH value is 2-3, and hydrolyzing to obtain silicon dioxide sol;
(2) adding the attapulgite fiber subjected to acid pickling pretreatment, uniformly mixing, adjusting the pH to 6-8 by using a carbonate/ammonia water mixed solution, transferring to a mold, standing to obtain silicon dioxide/attapulgite fiber composite hydrogel, and aging;
(3) taking out the silicon dioxide/attapulgite fiber composite hydrogel from the mold, and soaking the hydrogel in a sodium bicarbonate aqueous solution for solvent replacement;
(4) and taking out the silica/attapulgite fiber composite hydrogel after solvent replacement, and fully drying to obtain the hydrophilic silica/attapulgite fiber composite aerogel.
Wherein, in the step (2), the aging temperature is 20-60 ℃ and the aging time is 24-48 hours.
Wherein, in the step (3), the replacement time is 12-24 hours.
In step (1), the organosilicon precursor: anhydrous ethanol: the deionized water is mixed in a molar ratio of 1: 7-15: 4 to 8. Ethanol is used to adjust the concentration of the organosilicon precursor.
In the step (1), the acidic catalyst is selected from one or a combination of at least two of hydrochloric acid, acetic acid and oxalic acid.
Preferably, the acid catalyst is a mixed solution of hydrochloric acid and oxalic acid, and the volume ratio of the mixed solution is 3: 1.
In the present invention, both the acid and the base can promote the hydrolysis reaction of the organosilicon precursor to produce the silica sol, but the basic catalyst has much stronger catalytic action on the hydrolysis reaction than the acid. The reaction speed is too fast by adopting a stronger catalyst, which is not beneficial to the amplification of the production process.
In the step (2), the diameter of the attapulgite fiber is 20-40 nm, and the length is 0.5-1.5 μm.
The attapulgite fiber is a porous chain-layered water-containing Fumei aluminosilicate clay mineral, and the natural attapulgite fiber is acicular, fibrous or fiber-aggregated, has a diameter of 10-60 nm, a length of up to micrometer, and a relatively large length-diameter ratio; compared with widely used glass fiber, the glass fiber has the characteristics of no toxicity, no harm, good biocompatibility, low price, rich sources and the like; the attapulgite fiber contains a large amount of OH groups, can be well combined with the Si-O-Si framework of the silicon dioxide aerogel, and is beneficial to the composition of the attapulgite fiber and the silicon dioxide aerogel.
The attapulgite fiber with the diameter of 20-40 nanometers and the length of 0.5-1.5 micrometers is selected, so that the function of enhancing the aerogel framework structure can be achieved, and cracks can not be generated in the aerogel framework due to the too large diameter.
In the step (2), the mass of the attapulgite fibers is 3-20% of that of the silica aerogel. The mass of the silicon dioxide aerogel is a theoretical value calculated by an organic silicon precursor. The attapulgite fiber can not be uniformly dispersed in the sol and can be settled at the bottom of the sol due to excessively high mass fraction, and the reinforcing effect on the silica aerogel framework is not obvious due to excessively low mass fraction.
In the step (2), the carbonate in the carbonate/ammonia water mixed solution is selected from one or a combination of at least two of sodium carbonate, sodium bicarbonate and ammonium bicarbonate. The volume ratio of the carbonate to the ammonia water is 1: 5.
Preferably, the carbonate/ammonia water mixed solution is a mixed solution of sodium carbonate and ammonia water.
In the step (3), the concentration of the sodium bicarbonate aqueous solution is 0.04-0.16 g/ml.
In step (3), the aqueous sodium bicarbonate solution displaces water and ethanol in the pores of the aerogel, and during the subsequent drying process, the sodium bicarbonate decomposes to generate carbon dioxide gas. Carbon dioxide gas in the micropores of the aerogel is not only beneficial to discharging water, but also can provide proper micropore pressure to inhibit the fragmentation of a silicon dioxide framework, and the integrity of the dried aerogel is ensured.
In the step (3), the sodium bicarbonate in the sodium bicarbonate water solution starts to be gradually decomposed at the temperature of more than 50 ℃ to generate carbon dioxide gas, and the carbon dioxide gas can be completely decomposed at the temperature of 270 ℃. Wherein, no carbon dioxide gas is generated before drying in the step (3), which is beneficial to the preparation of wet gel.
In the step (4), the silicon dioxide/attapulgite fiber composite aerogel is dried at 50-70 ℃ for 10-20 min, washed by deionized water and dried at 80-270 ℃ to obtain the hydrophilic silicon dioxide/attapulgite fiber composite aerogel.
Preferably, after being washed by deionized water, the hydrophilic silica/attapulgite fiber composite aerogel is obtained by drying at 120 ℃ and 270 ℃ in sequence. The carbon dioxide gas generation rate is neutralized to ensure that the sodium bicarbonate is completely decomposed.
Preferably, the organosilicon precursor: anhydrous ethanol: the deionized water is mixed in a molar ratio of 1: 10-15: 6, the mass of the attapulgite fiber is 15-20% of that of the silicon dioxide aerogel, and the concentration of the sodium bicarbonate aqueous solution is 0.1-0.14 g/ml. Under the cooperation of the various conditions, the prepared silicon dioxide/attapulgite fiber composite aerogel has better heat-conducting property and compression property.
The normal pressure preparation method also comprises the following steps: and (3) soaking the hydrophilic silica/attapulgite fiber composite aerogel in a silane coupling agent solution for surface modification, and drying to obtain the hydrophobic silica/attapulgite fiber composite aerogel.
The silane coupling agent solution is selected from one or the combination of at least two of aminopropyltriethoxysilane, aminopropyltrimethoxysilane, silanetriol sodium propionate, N- [ (3-trimethoxysilyl) propyl ] ethylenediamine trisodium triacetate and trimethylchlorosilane solution.
According to the normal pressure preparation method of the silicon dioxide/attapulgite fiber composite aerogel, provided by the invention, carbon dioxide gas is generated through reaction in the holes of silicon dioxide gel, and a method combining certain pressure filling and natural fiber modification is adopted, so that the silicon dioxide/attapulgite fiber composite block aerogel with hydrophobic or hydrophilic characteristics is obtained; the defects of large investment, low efficiency and safety and the like of the traditional supercritical drying process are overcome, the problems of shrinkage, deformation and serious rupture in the conventional normal-pressure preparation process are solved, and the normal-pressure drying preparation of the whole aerogel is realized.
The silicon dioxide/attapulgite fiber composite aerogel prepared by the method has the characteristics of no fragmentation, uniform pore size distribution, low thermal conductivity, good mechanical property and the like; the invention can carry out normal pressure drying without time-consuming repeated solvent replacement and surface modification, shortens the preparation period, saves the production cost and is convenient for industrial production.
Drawings
FIG. 1 is a flow chart of an atmospheric pressure preparation method of silica/attapulgite fiber composite aerogel according to the present invention;
FIG. 2 is an optical photograph of a bulk silica/attapulgite fiber composite aerogel prepared in example 6;
FIG. 3 is an SEM photograph of a bulk silica/attapulgite fiber composite aerogel prepared in example 6;
FIG. 4 is an SEM photograph of the silica/attapulgite fiber composite aerogel prepared in example 6;
FIG. 5 is an optical photograph of the silica/attapulgite fiber composite aerogel prepared in comparative example 2;
fig. 6 is an SEM photograph of the silica/attapulgite fiber composite aerogel prepared in comparative example 2.
Detailed Description
In order to more specifically describe the present invention, the following detailed description is provided for the technical solution of the present invention with reference to the accompanying drawings and the specific embodiments.
A normal pressure preparation method of silicon dioxide/attapulgite fiber composite aerogel comprises the following steps:
(1) uniformly mixing an organic silicon precursor, absolute ethyl alcohol and deionized water, adding an acidic catalyst until the pH value is 2-3, and hydrolyzing for 30 minutes to obtain silicon dioxide sol;
(2) adding the attapulgite fibers subjected to acid pickling pretreatment, uniformly mixing, adjusting the pH to 6-8 by using a carbonate/ammonia water mixed solution, transferring the mixture into a mold, standing to obtain silicon dioxide/attapulgite fiber composite hydrogel, and aging at 20-60 ℃ for 24-48 hours;
(3) taking out the silicon dioxide/attapulgite fiber composite hydrogel from the mold, and soaking the silicon dioxide/attapulgite fiber composite hydrogel in a sodium bicarbonate aqueous solution for solvent replacement for 12-24 hours;
(4) and taking out the silica/attapulgite fiber composite hydrogel after solvent replacement, and fully drying to obtain the hydrophilic silica/attapulgite fiber composite aerogel.
Example 1
At room temperature (25 ℃), tetraethyl orthosilicate, absolute ethanol and deionized water are mixed according to a molar ratio of 1: 7: 4, uniformly mixing and stirring, adding a mixed solution of hydrochloric acid and oxalic acid to adjust the pH value to 2, stirring for 30min, adding 3 wt.% of attapulgite fibers which are pretreated by acid washing and have the diameter of 20-40 nm and the length of 0.5-1.5 mu m into the mixed solution, and performing ultrasonic treatment for 10min to uniformly disperse the attapulgite fibers; adding a sodium carbonate/ammonia water mixed solution to adjust the pH value to 6, stirring, sealing and standing to obtain silicon dioxide/attapulgite fiber composite hydrogel; adding 40mL of absolute ethyl alcohol into the obtained silicon dioxide/attapulgite fiber composite hydrogel, sealing, and aging in a water bath kettle at 20 ℃ for 24 hours; after aging, taking out the silicon dioxide/attapulgite fiber composite hydrogel from the mold, and soaking the silicon dioxide/attapulgite fiber composite hydrogel in 0.04mol/L sodium bicarbonate aqueous solution for solvent replacement for 12 hours; and (3) after replacement, drying at 50 ℃ for 20min, then washing in deionized water, drying at 80 ℃ for 12h, and drying at 270 ℃ for 6h to obtain the hydrophilic silicon dioxide/attapulgite fiber composite aerogel.
Example 2
At room temperature (25 ℃), tetraethyl orthosilicate, absolute ethanol and deionized water are mixed according to a molar ratio of 1: 7: 8, uniformly mixing and stirring, adding acetic acid to adjust the pH value to 3, stirring for 30min, adding 15 wt.% of attapulgite fibers which are subjected to acid cleaning pretreatment and have the diameter of 20-40 nm and the length of 0.5-1.5 mu m into the mixed solution, and performing ultrasonic treatment for 10min to uniformly disperse the attapulgite fibers; adding a sodium bicarbonate/ammonia water mixed solution to adjust the pH value to 7, stirring, sealing and standing to obtain the silicon dioxide/attapulgite fiber composite hydrogel; adding 40mL of absolute ethyl alcohol into the obtained silicon dioxide/attapulgite fiber composite hydrogel, sealing, and aging in a 40 ℃ water bath kettle for 36 h; after aging, taking out the silicon dioxide/attapulgite fiber composite hydrogel from the mold, and soaking the silicon dioxide/attapulgite fiber composite hydrogel in 0.1mol/L sodium bicarbonate aqueous solution for solvent replacement for 18 hours; and (3) drying at 60 ℃ for 15min after replacement, then washing in deionized water, drying at 120 ℃ for 12h, and drying at 270 ℃ for 6h to obtain the hydrophilic silicon dioxide/attapulgite fiber composite aerogel.
Example 3
At room temperature (25 ℃), tetraethyl orthosilicate, absolute ethanol and deionized water are mixed according to a molar ratio of 1: 7: 6, uniformly mixing and stirring, adding hydrochloric acid to adjust the pH value to 3, stirring for 30min, adding 20 wt.% of attapulgite fibers which are subjected to acid cleaning pretreatment and have the diameter of 20-40 nm and the length of 0.5-1.5 mu m into the mixed solution, and performing ultrasonic treatment for 10min to uniformly disperse the attapulgite fibers; adding ammonium bicarbonate/ammonia water mixed solution to adjust the pH value to 8, stirring, sealing and standing to obtain silicon dioxide/attapulgite fiber composite hydrogel; adding 40mL of absolute ethyl alcohol into the obtained silicon dioxide/attapulgite fiber composite hydrogel, sealing, and aging in a 60 ℃ water bath kettle for 48 hours; after aging, taking out the silicon dioxide/attapulgite fiber composite hydrogel from the mold, and soaking the silicon dioxide/attapulgite fiber composite hydrogel in 0.14mol/L sodium bicarbonate aqueous solution for solvent replacement for 24 hours; and (3) after replacement, drying at 70 ℃ for 10min, then washing in deionized water, drying at 120 ℃ for 12h, and drying at 270 ℃ for 6h to obtain the hydrophilic silicon dioxide/attapulgite fiber composite aerogel.
Example 4
At room temperature (25 ℃), tetraethyl orthosilicate, absolute ethanol and deionized water are mixed according to a molar ratio of 1: 7: 4, uniformly mixing and stirring, adding oxalic acid mixed liquor to adjust the pH value to 3, stirring for 30min, adding 20 wt.% of attapulgite fibers which are pretreated by acid washing and have the diameter of 20-40 nm and the length of 0.5-1.5 mu m into the mixed solution, and performing ultrasonic treatment for 10min to uniformly disperse the attapulgite fibers; adding a sodium carbonate/ammonia water mixed solution to adjust the pH value to 8, stirring, sealing and standing to obtain silicon dioxide/attapulgite fiber composite hydrogel; adding 40mL of absolute ethyl alcohol into the obtained silicon dioxide/attapulgite fiber composite hydrogel, sealing, and aging in a 60 ℃ water bath kettle for 48 hours; after aging, taking out the silicon dioxide/attapulgite fiber composite hydrogel from the mold, and soaking the silicon dioxide/attapulgite fiber composite hydrogel in 0.16mol/L sodium bicarbonate aqueous solution for solvent replacement for 24 hours; and (3) after replacement, drying at 70 ℃ for 10min, then washing in deionized water, drying at 120 ℃ for 12h, and drying at 270 ℃ for 6h to obtain the hydrophilic silicon dioxide/attapulgite fiber composite aerogel.
Example 5
At room temperature (25 ℃), tetraethyl orthosilicate, absolute ethanol and deionized water are mixed according to a molar ratio of 1: 10: 6, uniformly mixing and stirring, adding a mixed solution of hydrochloric acid and oxalic acid to adjust the pH value to 2, stirring for 30min, adding 3 wt.% of attapulgite fibers which are pretreated by acid washing and have the diameter of 20-40 nm and the length of 0.5-1.5 mu m into the mixed solution, and performing ultrasonic treatment for 10min to uniformly disperse the attapulgite fibers; adding a sodium carbonate/ammonia water mixed solution to adjust the pH value to 6, stirring, sealing and standing to obtain silicon dioxide/attapulgite fiber composite hydrogel; adding 40mL of absolute ethyl alcohol into the obtained silicon dioxide/attapulgite fiber composite hydrogel, sealing, and aging in a water bath kettle at 20 ℃ for 24 hours; after aging, taking out the silicon dioxide/attapulgite fiber composite hydrogel from the mold, and soaking the silicon dioxide/attapulgite fiber composite hydrogel in 0.04mol/L sodium bicarbonate aqueous solution for solvent replacement for 12 hours; and (3) after replacement, drying at 50 ℃ for 20min, then putting the obtained product into deionized water to be cleaned, and drying at 120 ℃ for 12h and at 270 ℃ for 6h to obtain the hydrophilic silicon dioxide/attapulgite fiber composite aerogel.
Example 6
At room temperature (25 ℃), tetraethyl orthosilicate, absolute ethanol and deionized water are mixed according to a molar ratio of 1: 10: 6, uniformly mixing and stirring, adding a mixed solution of hydrochloric acid and oxalic acid to adjust the pH value to 3, stirring for 30min, adding 15 wt.% of attapulgite fibers which are pretreated by acid washing and have the diameter of 20-40 nm and the length of 0.5-1.5 mu m into the mixed solution, and performing ultrasonic treatment for 10min to uniformly disperse the attapulgite fibers; adding a sodium carbonate/ammonia water mixed solution to adjust the pH value to 7, stirring, sealing and standing to obtain silicon dioxide/attapulgite fiber composite hydrogel; adding 40mL of absolute ethyl alcohol into the obtained silicon dioxide/attapulgite fiber composite hydrogel, sealing, and aging in a 40 ℃ water bath kettle for 36 h; after aging, taking out the silicon dioxide/attapulgite fiber composite hydrogel from the die, and soaking the silicon dioxide/attapulgite fiber composite hydrogel in 0.1mol/L sodium bicarbonate aqueous solution for solvent replacement for 18 hours; and (3) drying at 60 ℃ for 15min after replacement, then washing in deionized water, drying at 120 ℃ for 12h, and drying at 270 ℃ for 6h to obtain the hydrophilic silicon dioxide/attapulgite fiber composite aerogel.
The prepared silicon dioxide/attapulgite fiber composite aerogel is very complete and has no obvious cracks as shown in figure 2; the microscopic morphology is shown in fig. 3 and 4, the holes are uniformly distributed, and the attapulgite fibers and the silicon dioxide particles are well combined together.
Example 7
At room temperature (25 ℃), tetraethyl orthosilicate, absolute ethanol and deionized water are mixed according to a molar ratio of 1: 10: 6, uniformly mixing and stirring, adding a mixed solution of hydrochloric acid and oxalic acid to adjust the pH value to 3, stirring for 30min, adding 20 wt.% of attapulgite fibers which are pretreated by acid washing and have the diameter of 20-40 nm and the length of 0.5-1.5 mu m into the mixed solution, and performing ultrasonic treatment for 10min to uniformly disperse the attapulgite fibers; adding a sodium carbonate/ammonia water mixed solution to adjust the pH value to 8, stirring, sealing and standing to obtain silicon dioxide/attapulgite fiber composite hydrogel; adding 40mL of absolute ethyl alcohol into the obtained silicon dioxide/attapulgite fiber composite hydrogel, sealing, and aging in a 60 ℃ water bath kettle for 48 hours; after aging, taking out the silicon dioxide/attapulgite fiber composite hydrogel from the mold, and soaking the silicon dioxide/attapulgite fiber composite hydrogel in 0.14mol/L sodium bicarbonate aqueous solution for solvent replacement for 24 hours; and (3) after replacement, drying at 70 ℃ for 10min, then washing in deionized water, drying at 120 ℃ for 12h, and drying at 270 ℃ for 6h to obtain the hydrophilic silicon dioxide/attapulgite fiber composite aerogel.
Example 8
At room temperature (25 ℃), tetraethyl orthosilicate, absolute ethanol and deionized water are mixed according to a molar ratio of 1: 15: 8, uniformly mixing and stirring, adding hydrochloric acid to adjust the pH value to 2, stirring for 30min, adding 3 wt.% of attapulgite fibers which are subjected to acid cleaning pretreatment and have the diameter of 20-40 nm and the length of 0.5-1.5 mu m into the mixed solution, and performing ultrasonic treatment for 10min to uniformly disperse the attapulgite fibers; adding a sodium carbonate/ammonia water mixed solution to adjust the pH value to 6, stirring, sealing and standing to obtain silicon dioxide/attapulgite fiber composite hydrogel; adding 40mL of absolute ethyl alcohol into the obtained silicon dioxide/attapulgite fiber composite hydrogel, sealing, and aging in a water bath kettle at 20 ℃ for 24 hours; after aging, taking out the silicon dioxide/attapulgite fiber composite hydrogel from the mold, and soaking the silicon dioxide/attapulgite fiber composite hydrogel in 0.04mol/L sodium bicarbonate aqueous solution for solvent replacement for 12 hours; and (3) after replacement, drying at 50 ℃ for 20min, then putting the obtained product into deionized water to be cleaned, and drying at 120 ℃ for 12h and at 270 ℃ for 6h to obtain the hydrophilic silicon dioxide/attapulgite fiber composite aerogel.
Example 9
At room temperature (25 ℃), tetraethyl orthosilicate, absolute ethanol and deionized water are mixed according to a molar ratio of 1: 15: 6, uniformly mixing and stirring, adding a mixed solution of hydrochloric acid and oxalic acid to adjust the pH value to 3, stirring for 30min, adding 15 wt.% of attapulgite fibers which are pretreated by acid washing and have the diameter of 20-40 nm and the length of 0.5-1.5 mu m into the mixed solution, and performing ultrasonic treatment for 10min to uniformly disperse the attapulgite fibers; adding a sodium carbonate/ammonia water mixed solution to adjust the pH value to 7, stirring, sealing and standing to obtain silicon dioxide/attapulgite fiber composite hydrogel; adding 40mL of absolute ethyl alcohol into the obtained silicon dioxide/attapulgite fiber composite hydrogel, sealing, and aging in a 40 ℃ water bath kettle for 36 h; after aging, taking out the silicon dioxide/attapulgite fiber composite hydrogel from the die, and soaking the silicon dioxide/attapulgite fiber composite hydrogel in 0.1mol/L sodium bicarbonate aqueous solution for solvent replacement for 18 hours; and (3) drying at 60 ℃ for 15min after replacement, then washing in deionized water, drying at 120 ℃ for 12h, and drying at 270 ℃ for 6h to obtain the hydrophilic silicon dioxide/attapulgite fiber composite aerogel.
Example 10
At room temperature (25 ℃), tetraethyl orthosilicate, absolute ethanol and deionized water are mixed according to a molar ratio of 1: 10: 4, uniformly mixing and stirring, adding a mixed solution of hydrochloric acid and oxalic acid to adjust the pH value to 3, stirring for 30min, adding 20 wt.% of attapulgite fibers which are pretreated by acid washing and have the diameter of 20-40 nm and the length of 0.5-1.5 mu m into the mixed solution, and performing ultrasonic treatment for 10min to uniformly disperse the attapulgite fibers; adding a sodium carbonate/ammonia water mixed solution to adjust the pH value to 8, stirring, sealing and standing to obtain silicon dioxide/attapulgite fiber composite hydrogel; adding 40mL of absolute ethyl alcohol into the obtained silicon dioxide/attapulgite fiber composite hydrogel, sealing, and aging in a 60 ℃ water bath kettle for 48 hours; after aging, taking out the silicon dioxide/attapulgite fiber composite hydrogel from the mold, and soaking the silicon dioxide/attapulgite fiber composite hydrogel in 0.16mol/L sodium bicarbonate aqueous solution for solvent replacement for 24 hours; and (3) after replacement, drying at 70 ℃ for 10min, then washing in deionized water, drying at 120 ℃ for 12h, and drying at 270 ℃ for 6h to obtain the hydrophilic silicon dioxide/attapulgite fiber composite aerogel.
Example 11
At room temperature (25 ℃), tetraethyl orthosilicate, absolute ethanol and deionized water are mixed according to a molar ratio of 1: 10: 6, uniformly mixing and stirring, adding a mixed solution of hydrochloric acid and oxalic acid to adjust the pH value to 3, stirring for 30min, adding 15 wt.% of attapulgite fibers which are pretreated by acid washing and have the diameter of 20-40 nm and the length of 0.5-1.5 mu m into the mixed solution, and performing ultrasonic treatment for 10min to uniformly disperse the attapulgite fibers; adding a sodium carbonate/ammonia water mixed solution to adjust the pH value to 7, stirring, sealing and standing to obtain silicon dioxide/attapulgite fiber composite hydrogel; adding 40mL of absolute ethyl alcohol into the obtained silicon dioxide/attapulgite fiber composite hydrogel, sealing, and aging in a 40 ℃ water bath kettle for 36 h; after aging, taking out the silicon dioxide/attapulgite fiber composite hydrogel from the die, and soaking the silicon dioxide/attapulgite fiber composite hydrogel in 0.1mol/L sodium bicarbonate aqueous solution for solvent replacement for 18 hours; after replacement, drying at 60 ℃ for 15min, then washing in deionized water, drying at 120 ℃ for 12h, and drying at 270 ℃ for 6h to obtain the hydrophilic silicon oxide attapulgite fiber composite aerogel; soaking the obtained hydrophilic silicon oxide attapulgite fiber composite aerogel in a trimethylchlorosilane solution diluted by normal hexane and ethanol, and modifying for 24 hours; cleaning for 24 hours by using normal hexane after modification; and then drying at 50 ℃ for 12h, drying at 85 ℃ for 3h, and drying at 125 ℃ for 1h to obtain the hydrophobic silicon oxide attapulgite fiber composite aerogel.
Comparative example 1
Tetraethyl orthosilicate, absolute ethyl alcohol and deionized water are mixed according to a molar ratio of 1: 10: 6, uniformly mixing and stirring, adding a mixed solution of hydrochloric acid and oxalic acid to adjust the pH value to 3, stirring for 30min, adding a sodium carbonate/ammonia water mixed solution to adjust the pH value to 7, stirring, sealing and standing to obtain silicon dioxide gel; adding the obtained silicon dioxide gel into 40mL of absolute ethyl alcohol, sealing, and aging in a water bath kettle at 40 ℃ for 36 h; after aging, taking out the silicon dioxide hydrogel from the mold, and soaking the silicon dioxide hydrogel in 0.1mol/L sodium bicarbonate aqueous solution for solvent replacement for 18 hours; and (3) drying at 60 ℃ for 15min after replacement, then washing in deionized water, drying at 120 ℃ for 12h, and drying at 270 ℃ for 6h to obtain the hydrophilic silica aerogel.
The specific surface area of the prepared silica aerogel was 562.0m2G, density 0.310g/cm3The thermal conductivity of the material is 0.028W/(m.k) and the compressive strength is 0.7MPa measured by a TC3200 thermal conductivity instrument.
Comparative example 2
Tetraethyl orthosilicate, absolute ethyl alcohol and deionized water are mixed according to a molar ratio of 1: 10: 6, uniformly mixing and stirring, adding a mixed solution of hydrochloric acid and oxalic acid to adjust the pH value to 2, stirring for 30min, adding 15 wt.% of attapulgite fibers which are pretreated by acid washing and have the diameter of 20-40 nm and the length of 0.5-1.5 mu m into the mixed solution, and performing ultrasonic treatment for 10min to uniformly disperse the attapulgite fibers; adding a sodium bicarbonate/ammonia water mixed solution to adjust the pH value to 7, stirring, sealing and standing to obtain the silicon dioxide/attapulgite fiber composite hydrogel; adding 40mL of absolute ethyl alcohol into the obtained silicon dioxide/attapulgite fiber composite hydrogel, sealing, and aging in a water bath kettle at 20 ℃ for 24 hours; and (3) taking out the silicon dioxide/attapulgite fiber composite hydrogel from the die after aging, then putting the silicon dioxide/attapulgite fiber composite hydrogel into deionized water to be cleaned, and drying the silicon dioxide/attapulgite fiber composite hydrogel at 120 ℃ for 12 hours and at 270 ℃ for 6 hours to obtain the hydrophilic silicon dioxide/attapulgite fiber composite aerogel.
The specific surface area of the prepared silicon dioxide/attapulgite fiber composite aerogel is 380.0m2G, density of 0.570g/cm3The thermal conductivity of the material was 0.040W/(m.k) and the compressive strength was 1.5MPa as measured by a TC3200 thermal conductivity instrument.
Fig. 5 is an optical photograph and an SEM photograph of the silica/attapulgite fiber composite aerogel prepared in comparative example 2 as shown in fig. 5 and 6, and it can be seen from fig. 5 that cracks of the composite aerogel are significant because carbon dioxide gas cannot be generated during drying without being replaced with a sodium bicarbonate solution before drying, and it can be seen from fig. 6 that the holes are not uniformly distributed and have significant microcracks.
TABLE 1 Performance test results of silica/Attapulgite fiber composite aerogels prepared in examples 1 to 11 and comparative examples 1 to 2
The above-mentioned embodiments are intended to illustrate the technical solutions and advantages of the present invention, and it should be understood that the above-mentioned embodiments are only the most preferred embodiments of the present invention, and are not intended to limit the present invention, and any modifications, additions, equivalents, etc. made within the scope of the principles of the present invention should be included in the scope of the present invention.
Claims (8)
1. A normal pressure preparation method of silicon dioxide/attapulgite fiber composite aerogel comprises the following steps:
(1) uniformly mixing an organic silicon precursor, absolute ethyl alcohol and deionized water, adding an acidic catalyst until the pH value is 2-3, and hydrolyzing to obtain silicon dioxide sol;
(2) adding the attapulgite fiber subjected to acid pickling pretreatment, uniformly mixing, adjusting the pH to 6-8 by using a carbonate/ammonia water mixed solution, transferring to a mold, standing to obtain silicon dioxide/attapulgite fiber composite hydrogel, and aging;
(3) taking out the silicon dioxide/attapulgite fiber composite hydrogel from the mold, and soaking the hydrogel in a sodium bicarbonate aqueous solution for solvent replacement;
(4) taking out the silica/attapulgite fiber composite hydrogel after solvent replacement, and fully drying to obtain hydrophilic silica/attapulgite fiber composite aerogel;
in the step (2), the diameter of the attapulgite fiber is 20-40 nm, and the length is 0.5-1.5 μm;
the mass of the attapulgite fiber is 3-20% of that of the silica sol.
2. The method for the atmospheric pressure preparation of silica/attapulgite fiber composite aerogel according to claim 1, wherein in step (1), the organosilicon precursor: anhydrous ethanol: the deionized water is mixed in a molar ratio of 1: 7-15: 4 to 8.
3. The atmospheric pressure preparation method of silica/attapulgite fiber composite aerogel according to claim 1, wherein in the step (1), the acidic catalyst is selected from one or a combination of at least two of hydrochloric acid, acetic acid and oxalic acid.
4. The atmospheric pressure preparation method of silica/attapulgite fiber composite aerogel according to claim 1, wherein in the step (2), the carbonate in the carbonate/ammonia water mixed solution is selected from one or a combination of at least two of sodium carbonate, sodium bicarbonate and ammonium bicarbonate.
5. The method for preparing the silica/attapulgite fiber composite aerogel under normal pressure according to claim 1, wherein in the step (3), the concentration of the sodium bicarbonate aqueous solution is 0.04-0.16 g/ml.
6. The normal-pressure preparation method of the silica/attapulgite fiber composite aerogel according to claim 1, wherein in the step (4), the silica/attapulgite fiber composite aerogel is dried at 50-70 ℃ for 10-20 min, washed with deionized water, and dried at 80-270 ℃ to obtain the hydrophilic silica/attapulgite fiber composite aerogel.
7. The method for preparing the silica/attapulgite fiber composite aerogel according to claim 2, wherein the organosilicon precursor is: anhydrous ethanol: the deionized water is mixed in a molar ratio of 1: 10-15: 6, the mass of the attapulgite fiber is 15-20% of that of the silica sol, and the concentration of the sodium bicarbonate aqueous solution is 0.1-0.14 g/ml.
8. The atmospheric preparation method of silica/attapulgite fiber composite aerogel according to claim 1, further comprising: and (3) soaking the obtained hydrophilic silica/attapulgite fiber composite aerogel in a silane coupling agent solution for surface modification, and drying to obtain the hydrophobic silica/attapulgite fiber composite aerogel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810688339.3A CN108484098B (en) | 2018-06-28 | 2018-06-28 | Normal-pressure preparation method of silicon dioxide/attapulgite fiber composite aerogel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810688339.3A CN108484098B (en) | 2018-06-28 | 2018-06-28 | Normal-pressure preparation method of silicon dioxide/attapulgite fiber composite aerogel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108484098A CN108484098A (en) | 2018-09-04 |
| CN108484098B true CN108484098B (en) | 2021-06-01 |
Family
ID=63343525
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810688339.3A Active CN108484098B (en) | 2018-06-28 | 2018-06-28 | Normal-pressure preparation method of silicon dioxide/attapulgite fiber composite aerogel |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108484098B (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109233310A (en) * | 2018-09-11 | 2019-01-18 | 界首永恩机电科技有限公司 | A kind of attapulgite and preparation method thereof for modifying plastics |
| CN109096658A (en) * | 2018-09-11 | 2018-12-28 | 界首永恩机电科技有限公司 | A kind of modified PVC pellet and preparation method thereof |
| CN109206789A (en) * | 2018-09-11 | 2019-01-15 | 界首永恩机电科技有限公司 | A kind of aerosil and preparation method thereof being modified for PVC |
| CN109250738B (en) * | 2018-09-19 | 2021-03-09 | 西南科技大学 | Preparation method of high-temperature resistant block alumina aerogel |
| CN110538485A (en) * | 2019-08-27 | 2019-12-06 | 河南大学 | Nano carbon nitride/copper oxide composite material, nano carbon nitride/copper oxide composite solid phase micro-extractor and preparation method and application thereof |
| CN113683388A (en) * | 2020-05-18 | 2021-11-23 | 淮阴工学院 | Preparation method of high-temperature-resistant flexible attapulgite composite aerogel |
| CN113680288A (en) * | 2020-05-18 | 2021-11-23 | 淮阴工学院 | Preparation method of hydrophobic attapulgite composite aerogel |
| CN111592329B (en) * | 2020-05-25 | 2022-06-03 | 福建拓烯新材料科技有限公司 | Preparation method of modified silica aerogel and modified silica aerogel |
| CN113750916A (en) * | 2021-08-18 | 2021-12-07 | 南京工业大学 | Preparation method of attapulgite-silicon dioxide composite aerogel microspheres |
| CN114933783B (en) * | 2022-05-31 | 2023-08-25 | 江苏恒烽显示科技有限公司 | Resin material for LED packaging and preparation method thereof |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103435055A (en) * | 2013-06-29 | 2013-12-11 | 浙江工业大学 | Method for preparing low density silica aerogel under normal pressure |
| CN105272143A (en) * | 2015-12-06 | 2016-01-27 | 北京工业大学 | Preparation method of low-cost hydrophobic silica aerogel heat insulation material enhanced through sepiolite fibers of different lengths |
| CN105621420A (en) * | 2015-12-23 | 2016-06-01 | 成都新柯力化工科技有限公司 | Method for preparing silicon dioxide aerogel through foaming |
-
2018
- 2018-06-28 CN CN201810688339.3A patent/CN108484098B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103435055A (en) * | 2013-06-29 | 2013-12-11 | 浙江工业大学 | Method for preparing low density silica aerogel under normal pressure |
| CN105272143A (en) * | 2015-12-06 | 2016-01-27 | 北京工业大学 | Preparation method of low-cost hydrophobic silica aerogel heat insulation material enhanced through sepiolite fibers of different lengths |
| CN105621420A (en) * | 2015-12-23 | 2016-06-01 | 成都新柯力化工科技有限公司 | Method for preparing silicon dioxide aerogel through foaming |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108484098A (en) | 2018-09-04 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108484098B (en) | Normal-pressure preparation method of silicon dioxide/attapulgite fiber composite aerogel | |
| CN108658573B (en) | Anti-powder-dropping aerogel composite heat-insulating felt | |
| CN101698584B (en) | Fiber-reinforcement silicon dioxide aerogel continuous felt and preparation method thereof | |
| CN101372337B (en) | Method for preparing transparent silicon dioxide aerogel by co-precursor normal atmosphere drying | |
| CN108218386B (en) | Preparation method of chlorosilane modified graphene oxide/silicon dioxide heat-insulation composite material | |
| CN108423685A (en) | The atmospheric preparation method of aerosil | |
| CN104787771B (en) | A kind of method for improving silicon dioxide silica aerogel composite material intensity | |
| CN102351507B (en) | Method for preparing fiber-reinforced SiO2 aerogel from rice husk ash as raw material | |
| CN105198375A (en) | Thermal insulation silicon dioxide aerogel/hydroxylation glass fiber felt composite and preparation method thereof | |
| CN101445356A (en) | Nano-hole aerogel heat-insulating composite material and preparation method thereof | |
| CN110467421B (en) | Functional cellulose aerogel composite material and preparation method thereof | |
| CN111607253B (en) | Preparation method of silica aerogel thermal insulation filler | |
| CN109251005B (en) | Preparation method of reinforced silica aerogel material | |
| CN102659120A (en) | Preparation method for hydrophobic large-size bulk nanometer porous SiO2 aerogel | |
| CN101633505A (en) | SiO2 nanoscale porous material with aerogel property prepared by microwave reaction and preparation method thereof | |
| CN110898772B (en) | Preparation method and application of composite organic aerogel | |
| CN111454041A (en) | Preparation method of fiber-reinforced silica aerogel | |
| CN110723738B (en) | Preparation method of enhanced silica aerogel, enhanced silica aerogel and application thereof | |
| CN108793173B (en) | Method for preparing modified silica aerogel material by adopting external circulation mode and normal pressure drying | |
| CN110565366B (en) | Preparation method of silicon aerogel composite material | |
| CN109179428B (en) | Enhanced transparent silicon dioxide aerogel and preparation method thereof | |
| WO2023226710A1 (en) | Method for preparing silicon dioxide aerogel or composite product thereof | |
| CN105036142B (en) | Preparation method for toughened SiO2 aerogel composite material | |
| CN112279612A (en) | Bionic 3D printing aerogel thermal insulation board and preparation method thereof | |
| CN112851292B (en) | Wave-transparent and efficient heat-insulating aerogel composite material and preparation method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |