CN113477236A - Preparation method of graphene oxide-polyethyleneimine/silicon dioxide composite aerogel - Google Patents
Preparation method of graphene oxide-polyethyleneimine/silicon dioxide composite aerogel Download PDFInfo
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 title claims abstract description 126
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 95
- 229910021389 graphene Inorganic materials 0.000 title claims abstract description 94
- 229920002873 Polyethylenimine Polymers 0.000 title claims abstract description 83
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- 238000002791 soaking Methods 0.000 claims abstract description 17
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- 230000001112 coagulating effect Effects 0.000 claims abstract description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 15
- WYTZZXDRDKSJID-UHFFFAOYSA-N (3-aminopropyl)triethoxysilane Chemical compound CCO[Si](OCC)(OCC)CCCN WYTZZXDRDKSJID-UHFFFAOYSA-N 0.000 claims description 8
- XJKVPKYVPCWHFO-UHFFFAOYSA-N silicon;hydrate Chemical compound O.[Si] XJKVPKYVPCWHFO-UHFFFAOYSA-N 0.000 claims description 7
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 claims description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 5
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- 238000004321 preservation Methods 0.000 claims description 2
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- 238000009210 therapy by ultrasound Methods 0.000 abstract 1
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- 229910002092 carbon dioxide Inorganic materials 0.000 description 10
- 238000000034 method Methods 0.000 description 10
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- VILCJCGEZXAXTO-UHFFFAOYSA-N 2,2,2-tetramine Chemical compound NCCNCCNCCN VILCJCGEZXAXTO-UHFFFAOYSA-N 0.000 description 2
- HZAXFHJVJLSVMW-UHFFFAOYSA-N 2-Aminoethan-1-ol Chemical compound NCCO HZAXFHJVJLSVMW-UHFFFAOYSA-N 0.000 description 2
- RPNUMPOLZDHAAY-UHFFFAOYSA-N Diethylenetriamine Chemical compound NCCNCCN RPNUMPOLZDHAAY-UHFFFAOYSA-N 0.000 description 2
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- LSHROXHEILXKHM-UHFFFAOYSA-N n'-[2-[2-[2-(2-aminoethylamino)ethylamino]ethylamino]ethyl]ethane-1,2-diamine Chemical compound NCCNCCNCCNCCNCCN LSHROXHEILXKHM-UHFFFAOYSA-N 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
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- FAGUFWYHJQFNRV-UHFFFAOYSA-N tetraethylenepentamine Chemical compound NCCNCCNCCNCCN FAGUFWYHJQFNRV-UHFFFAOYSA-N 0.000 description 2
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- 150000001721 carbon Chemical group 0.000 description 1
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- 238000013329 compounding Methods 0.000 description 1
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical compound OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 description 1
- LVTYICIALWPMFW-UHFFFAOYSA-N diisopropanolamine Chemical compound CC(O)CNCC(C)O LVTYICIALWPMFW-UHFFFAOYSA-N 0.000 description 1
- 229940043276 diisopropanolamine Drugs 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/20—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
- B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
- B01J20/103—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate comprising silica
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- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
- B01J20/26—Synthetic macromolecular compounds
- B01J20/261—Synthetic macromolecular compounds obtained by reactions only involving carbon to carbon unsaturated bonds
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
- B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
- B01J20/28047—Gels
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/50—Carbon oxides
- B01D2257/504—Carbon dioxide
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
- Y02C20/00—Capture or disposal of greenhouse gases
- Y02C20/40—Capture or disposal of greenhouse gases of CO2
Abstract
The invention discloses a preparation method of graphene oxide-polyethyleneimine/silicon dioxide composite aerogel, which comprises the following steps: firstly, carrying out ultrasonic treatment on a graphene oxide aqueous solution to obtain a graphene oxide dispersion liquid and adjusting the pH value; secondly, mixing the graphene oxide and the polyethyleneimine with a polyethyleneimine water solution to obtain a graphene oxide-polyethyleneimine mixed solution; thirdly, after the mold is filled, keeping the temperature and standing the mold to obtain the graphene oxide-polyethyleneimine hydrogel; fourthly, adding the silicon dioxide precursor solution into the graphene oxide-polyethyleneimine hydrogel for soaking and coagulating to obtain composite hydrogel; and fifthly, carrying out solution replacement and freeze drying to obtain the graphene oxide-polyethyleneimine/silicon dioxide composite aerogel. According to the preparation method, the graphene oxide-polyethyleneimine hydrogel with the communicated pore channel structure is prepared firstly, and then the composite silica is impregnated to obtain the composite aerogel, so that the amine functional group loading capacity is improved, the sensitive crushing phenomenon of the silica gel is avoided, and the adsorption performance of the composite aerogel is improved.
Description
Technical Field
The invention belongs to the technical field of aerogel composite materials, and particularly relates to a preparation method of graphene oxide-polyethyleneimine/silicon dioxide composite aerogel.
Background
In recent years, greenhouse gases, particularly carbon dioxide, have been emitted in the atmosphere in an increasing amount through activities such as combustion and industrial emissions. Due to their high absorptive capacity, they are closely related to the observed surface temperature rise and global temperature changes. Therefore, in order to reduce the potential risk of greenhouse gases to climate change and the health of natural ecosystem and reduce the emission of carbon dioxide in the atmosphere, it is urgent to design and prepare a material with recyclability, higher pressure resistance and larger carbon dioxide adsorption capacity.
Graphene is a special two-dimensional honeycomb material consisting of sp hybridized orbitals of carbon atoms, has a special single-layer carbon atom hexagonal lattice structure, and thus shows good flexibility and structural stability, and has special physical and chemical properties such as high electrical conductivity, high thermal conductivity, high biocompatibility and high light transmittance, so that the graphene has wide application prospects in the aspects of biomedicine, micro-nano processing, materials science, electronic components and the like. Meanwhile, the three-dimensional graphene aerogel shows high adsorption capacity to carbon dioxide in the field of energy environments. The graphene oxide is used as one of graphene derivatives, and the single-layer material can be prepared and assembled into the three-dimensional graphene aerogel on different scales by non-performing functional group reaction and grafting on hydroxyl, epoxy and carboxyl distributed on the surface of a sheet layer of the graphene oxide.
The silica aerogel is a three-dimensional network structure nano porous material with low thermal conductivity, refractive index, low density, high specific surface area and high porosity, has attracted wide attention in recent years due to excellent performance, and is mainly applied to a heat insulation system in the field of aerospace, heat radiation management of earth engineering and carbon dioxide adsorption in environmental engineering. However, the disadvantages are also evident due to the severe requirements for temperature and pressure during their preparation: difficulty in maintaining a complete structure, poor mechanical properties, and too low carbon dioxide adsorption capacity. Therefore, it is necessary to improve the mechanical properties of the composite material by combining the graphene and the silica precursor, and to design the composite material to integrate the structural functions.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide a method for preparing graphene oxide-polyethyleneimine/silica composite aerogel, aiming at the defects of the prior art. According to the method, the graphene oxide-polyethyleneimine hydrogel with a communicated pore channel structure is prepared by a sol-gel method, and then the physical impregnation method is combined to compound silica to obtain the graphene oxide-polyethyleneimine/silica composite aerogel with a complete structure and high strength, so that the amine functional capacity is improved, the sensitive crushing phenomenon of silica gel is avoided, and the adsorption performance of the graphene oxide-polyethyleneimine/silica composite aerogel is greatly improved.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: the preparation method of the graphene oxide-polyethyleneimine/silicon dioxide composite aerogel is characterized by comprising the following steps of:
stripping a graphene oxide aqueous solution through an ultrasonic water bath to obtain a uniformly dispersed graphene oxide dispersion liquid, and then adjusting the pH value by using a sodium hydroxide aqueous solution;
step two, mixing the graphene oxide dispersion liquid with the pH value adjusted in the step one with a polyethyleneimine aqueous solution to prepare a graphene oxide-polyethyleneimine mixed liquid;
step three, putting the graphene oxide-polyethyleneimine mixed solution obtained in the step two into a mold, then carrying out heat preservation and standing, then demoulding and soaking by adopting deionized water to obtain graphene oxide-polyethyleneimine hydrogel;
step four, preparing a silicon dioxide precursor solution, adding the graphene oxide-polyethyleneimine hydrogel obtained in the step three, and soaking and condensing under a low-temperature condition to obtain a composite hydrogel;
and step five, sequentially carrying out solution replacement and freeze drying on the composite hydrogel obtained in the step four to obtain the graphene oxide-polyethyleneimine/silicon dioxide composite aerogel.
Aiming at the defects of sensitive and fragile property and poor mechanical property of the traditional silicon dioxide aerogel, the invention uses graphene oxide and silicon dioxide as precursors and polyethyleneimine as a cross-linking agent, firstly prepares graphene oxide-polyethyleneimine hydrogel by a sol-gel method, then adopts a physical impregnation method to compound silicon dioxide, and removes solvent and moisture by solution replacement and freeze drying to obtain the graphene oxide-polyethyleneimine/silicon dioxide composite aerogel with a complete structure and high strength. According to the method, hydrogen bonds between a graphene oxide sheet layer and a high amine cross-linking agent interact with static electricity to form the graphene oxide-polyethyleneimine hydrogel with a communicated pore structure, the loading capacity on amine functional groups is improved, the silicon dioxide aerogel with the same amine functional groups is attached to the pores of the graphene oxide-polyethyleneimine gel through a physical impregnation method, the graphene oxide-polyethyleneimine gel has good mechanical properties, so that the sensitive crushing phenomenon of the silicon dioxide gel is avoided, the graphene oxide-polyethyleneimine gel is cooperated to exert the bonding effect of the amine functional groups, and the adsorption capacity of the graphene oxide-polyethyleneimine/silicon dioxide composite aerogel on carbon dioxide is greatly improved.
The preparation method of the graphene oxide-polyethyleneimine/silicon dioxide composite aerogel is characterized in that in the first step, the concentration of the graphene oxide aqueous solution is 2 mg/mL-10 mg/mL, the concentration of the sodium hydroxide aqueous solution is 4mg/mL, and the adjusted pH value is 8.0. The optimized pH value effectively prevents the graphene oxide dispersion liquid from forming flocculation when being mixed with the polyethyleneimine water solution, and ensures the smooth proceeding of the subsequent hydrogel preparation.
The preparation method of the graphene oxide-polyethyleneimine/silicon dioxide composite aerogel is characterized in that in the second step, the concentration of the polyethyleneimine water solution is 10 mg/mL-30 mg/mL, and the volume ratio of the graphene oxide dispersion solution after the pH value is adjusted to the polyethyleneimine water solution is 1: 1.
The preparation method of the graphene oxide-polyethyleneimine/silicon dioxide composite aerogel is characterized by comprising the third step of pouring the graphene oxide-polyethyleneimine mixed solution into a mold, covering the mold with a preservative film, pricking small holes in the preservative film, and then keeping the temperature at 20-90 ℃ for 12-24 hours; the soaking time of the deionized water is 1 h. The preferred soaking time sufficiently removes unreacted residual polyethyleneimine on the surface of the hydrogel, and avoids adverse effects on the subsequent soaking coagulation compounding process.
The preparation method of the graphene oxide-polyethyleneimine/silicon dioxide composite aerogel is characterized in that the preparation process of the silicon dioxide precursor solution in the fourth step is as follows: selecting ethyl silicate TEOS and gamma-aminopropyltriethoxysilane APTES as precursors, and mixing the precursors with water according to the ratio of 1: preparing a silicon dioxide precursor solution according to the silicon-water ratio of 3-7, and controlling the silicon content to be 0.8-1.6 mol/L; the time for soaking and coagulating is 12-24 h. The preparation method is characterized in that the amine-grafted silicon dioxide gel is prepared by preferably controlling the composition of the precursor, so that the adsorption performance of the composite aerogel is improved; the internal pore size of the silicon dioxide aerogel is adjusted by controlling the silicon-water ratio, so that the silicon dioxide aerogel is ensured to be attached to the pore channel of the graphene oxide-polyethyleneimine gel, the graphene oxide-polyethyleneimine gel is prevented from being broken, and the adsorption performance is exerted.
The preparation method of the graphene oxide-polyethyleneimine/silicon dioxide composite aerogel is characterized in that in the fifth step, the temperature of freeze drying is less than-4 ℃ and the pressure is less than 20 Pa. The optimized freeze-drying process parameters ensure that water in the composite hydrogel is frozen and sublimated, so that the silicon dioxide gel is attached to the pore channel of the graphene oxide-polyethyleneimine gel to form a composite aerogel structure.
Compared with the prior art, the invention has the following advantages:
1. according to the invention, the graphene oxide-polyethyleneimine hydrogel with a communicated pore structure is prepared by a sol-gel method, and then the physical impregnation method is combined to compound silica, so that the graphene oxide-polyethyleneimine/silica composite aerogel with a complete structure and high strength is obtained, the amine functional capacity is improved, and the adsorption performance of the graphene oxide-polyethyleneimine/silica composite aerogel is greatly improved.
2. The silicon dioxide gel in the composite aerogel prepared by the invention is attached to the pore channel of the graphene oxide-polyethyleneimine gel, so that the sensitive crushing phenomenon of the silicon dioxide gel is avoided, the structural integrity of the composite aerogel is maintained, and the mechanical property of the composite aerogel is effectively improved.
3. According to the invention, the internal pore size of the silicon dioxide aerogel is adjusted by controlling the silicon-water ratio in the silicon dioxide precursor solution, so that the silicon dioxide aerogel is ensured to be attached to the pore channel of the graphene oxide-polyethyleneimine gel, the graphene oxide-polyethyleneimine gel is prevented from being broken, and the adsorption performance is further exerted.
4. The preparation method disclosed by the invention is simple in process and strong in practicability, can be used for preparing the composite aerogel by replacing polyethyleneimine with other amine species such as ethanolamine MEA, diethanolamine DEA, ethylenediamine EDA, diethylenetriamine DETA, triethylenetetramine TETA, tetraethylenepentamine TEPA, pentaethylenehexamine PEHA, polyethyleneimine PEI, diisopropanolamine IPA and APTES 3-aminopropyltriethoxysilane, and is wide in application range and high in practical value.
5. The preparation process of the invention is simple and pollution-free, the raw materials are easy to obtain, the cost is lower, and the invention is easy to popularize and apply.
The technical solution of the present invention is further described in detail by the accompanying drawings and examples.
Drawings
Fig. 1 is an external morphology diagram of a graphene oxide-polyethyleneimine/silica composite aerogel prepared in example 1 of the present invention.
Fig. 2 is an SEM image of a surface micro-topography of the graphene oxide-polyethyleneimine/silica composite aerogel prepared in example 1 of the present invention.
Fig. 3 is a carbon dioxide adsorption curve diagram of the graphene oxide-polyethyleneimine/silica composite aerogel prepared in example 1 of the present invention.
Detailed Description
Example 1
The embodiment comprises the following steps:
step one, stripping a graphene oxide aqueous solution with the concentration of 2mg/mL through an ultrasonic water bath for 1h to obtain a uniformly dispersed graphene oxide dispersion liquid, and then adjusting the pH value to 8.0 by adopting a sodium hydroxide aqueous solution with the concentration of 4 mg/mL;
step two, mixing the graphene oxide dispersion liquid with the pH value adjusted in the step one with a 10mg/mL polyethyleneimine aqueous solution according to a volume ratio of 1:1 to prepare a graphene oxide-polyethyleneimine mixed solution, and soaking and condensing for 24 hours at a low temperature of 0 ℃;
pouring the graphene oxide-polyethyleneimine mixed solution subjected to soaking and coagulation in the step two into a mold, covering the mold with a preservative film, pricking small holes in the preservative film, keeping the temperature and standing for 24 hours at 20 ℃, then demoulding, and soaking for 1 hour with deionized water to obtain graphene oxide-polyethyleneimine hydrogel;
step four, selecting ethyl silicate TEOS and gamma-aminopropyltriethoxysilane APTES as precursors, preparing a silicon dioxide precursor solution by using the precursors and water according to a silicon-water ratio of 1:3, controlling the silicon content to be 0.8mol/L, adding the graphene oxide-polyethyleneimine hydrogel obtained in the step three, and soaking and condensing for 24 hours at a low temperature of 0 ℃ to obtain a composite hydrogel;
step five, sequentially carrying out solution replacement and freeze drying on the composite hydrogel obtained in the step four to obtain the graphene oxide-polyethyleneimine/silicon dioxide composite aerogel; the temperature of the freeze drying is-80 ℃, the pressure is 0.1Pa, and the time is 48 h.
Fig. 1 is an external appearance diagram of the graphene oxide-polyethyleneimine/silica composite aerogel prepared in this embodiment, and as can be seen from fig. 1, the composite aerogel contains two matrix materials, wherein white is silica aerogel, and black is graphene oxide-polyethyleneimine aerogel.
Fig. 2 is a SEM image of a surface micro-topography of the graphene oxide-polyethyleneimine/silica composite aerogel prepared in this embodiment, and as can be seen from fig. 2, in the composite aerogel, a composite structure is formed by the lamellar graphene oxide-polyethyleneimine material and the spherule silica aerogel.
Fig. 3 is a carbon dioxide adsorption curve diagram of the graphene oxide-polyethyleneimine/silica composite aerogel prepared in this example, and it can be seen from fig. 3 that the adsorption amount of the composite aerogel to carbon dioxide gas increases with the increase of pressure, but does not show saturation, which is a typical feature of a porous material, and illustrates that the composite aerogel of the present invention has a porous structure.
Example 2
The present embodiment is different from embodiment 1 in that: selecting a graphene oxide aqueous solution with the concentration of 5mg/mL in the first step; selecting a polyethyleneimine water solution with the concentration of 20mg/mL in the second step; keeping the temperature and standing for 18h at 50 ℃ in the third step; and step four, preparing a silicon dioxide precursor solution from the precursor and water according to a silicon-water ratio of 1:5, controlling the silicon content to be 1.2mol/L, and soaking and condensing the hydrogel for 18 hours at the low temperature of 0 ℃.
Example 3
The present embodiment is different from embodiment 1 in that: selecting a graphene oxide aqueous solution with the concentration of 10mg/mL in the first step; selecting a 30mg/mL polyethyleneimine water solution in the second step; keeping the temperature and standing for 12 hours at 90 ℃ in the third step; and step four, preparing a silicon dioxide precursor solution from the precursor and water according to a silicon-water ratio of 1:7, controlling the silicon content to be 1.6mol/L, and soaking and condensing the hydrogel for 12 hours at the low temperature of 0 ℃.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention in any way. Any simple modification, change and equivalent changes of the above embodiments according to the technical essence of the invention are still within the protection scope of the technical solution of the invention.
Claims (6)
1. The preparation method of the graphene oxide-polyethyleneimine/silicon dioxide composite aerogel is characterized by comprising the following steps of:
stripping a graphene oxide aqueous solution through an ultrasonic water bath to obtain a uniformly dispersed graphene oxide dispersion liquid, and then adjusting the pH value by using a sodium hydroxide aqueous solution;
step two, mixing the graphene oxide dispersion liquid with the pH value adjusted in the step one with a polyethyleneimine aqueous solution to prepare a graphene oxide-polyethyleneimine mixed liquid;
step three, putting the graphene oxide-polyethyleneimine mixed solution obtained in the step two into a mold, then carrying out heat preservation and standing, then demoulding and soaking by adopting deionized water to obtain graphene oxide-polyethyleneimine hydrogel;
step four, preparing a silicon dioxide precursor solution, adding the graphene oxide-polyethyleneimine hydrogel obtained in the step three, and soaking and condensing under a low-temperature condition to obtain a composite hydrogel;
and step five, sequentially carrying out solution replacement and freeze drying on the composite hydrogel obtained in the step four to obtain the graphene oxide-polyethyleneimine/silicon dioxide composite aerogel.
2. The preparation method of the graphene oxide-polyethyleneimine/silica composite aerogel according to claim 1, wherein in the first step, the concentration of the graphene oxide aqueous solution is 2mg/mL to 10mg/mL, the concentration of the sodium hydroxide aqueous solution is 4mg/mL, and the adjusted pH value is 8.0.
3. The preparation method of the graphene oxide-polyethyleneimine/silica composite aerogel according to claim 1, wherein in the second step, the concentration of the polyethyleneimine aqueous solution is 10mg/mL to 30mg/mL, and the volume ratio of the graphene oxide dispersion solution after the pH is adjusted to the polyethyleneimine aqueous solution is 1: 1.
4. The preparation method of the graphene oxide-polyethyleneimine/silicon dioxide composite aerogel according to claim 1, wherein in the third step, the graphene oxide-polyethyleneimine mixed solution is poured into a mold, covered by a preservative film, perforated with small holes, and then kept at a temperature of 20-90 ℃ for 12-24 hours; the soaking time of the deionized water is 1 h.
5. The preparation method of the graphene oxide-polyethyleneimine/silica composite aerogel according to claim 1, wherein the preparation process of the silica precursor solution in the fourth step is as follows: selecting ethyl silicate TEOS and gamma-aminopropyltriethoxysilane APTES as precursors, and mixing the precursors with water according to the ratio of 1: preparing a silicon dioxide precursor solution according to the silicon-water ratio of 3-7, and controlling the silicon content to be 0.8-1.6 mol/L; the time for soaking and coagulating is 12-24 h.
6. The preparation method of the graphene oxide-polyethyleneimine/silicon dioxide composite aerogel according to claim 1, wherein the temperature of freeze drying in step five is less than-4 ℃ and the pressure is less than 20 Pa.
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