阅读说明：本技术 一种双网络气凝胶及其制备方法和应用 (Double-network aerogel and preparation method and application thereof ) 是由 郝一男 柴源 张永强 王晶文 王喜明 岳宏泽 李晓东 李泽鑫 赵凯怡 杜庆巍 于 2021-08-30 设计创作，主要内容包括：本发明公开了一种双网络气凝胶及其制备方法和应用,属于材料制备技术领域。具体公开了制备方法为：将木材于冰乙酸和双氧水的混合溶液中浸渍,制备得到各向异性的纤维素基气凝胶；以丙烯酰胺为单体,N-N’亚甲基双丙烯酰胺为交联剂,过硫酸铵为引发剂,制得水凝胶溶液；然后将制备好的纤维素基气凝胶置于水凝胶溶液中加热反应,经过冷冻干燥得到双网络气凝胶。本发明制备工序简单,原料来源广泛造价低廉,为染料废水的脱色处理提供了一种新材料。(The invention discloses a double-network aerogel and a preparation method and application thereof, and belongs to the technical field of material preparation. The preparation method is specifically disclosed as follows: soaking wood in a mixed solution of glacial acetic acid and hydrogen peroxide to prepare anisotropic cellulose-based aerogel; preparing a hydrogel solution by using acrylamide as a monomer, N-N' methylene bisacrylamide as a cross-linking agent and ammonium persulfate as an initiator; and then placing the prepared cellulose-based aerogel in a hydrogel solution for heating reaction, and performing freeze drying to obtain the double-network aerogel. The invention has simple preparation process, wide raw material source and low cost, and provides a new material for the decolorization treatment of dye wastewater.)

1. The preparation method of the double-network aerogel is characterized by comprising the following steps:

soaking the wood in a mixed solution of glacial acetic acid and hydrogen peroxide, washing the soaked wood to be neutral, and freeze-drying after pre-freezing treatment to obtain aerogel;

preparing acrylamide and N-N' methylene bisacrylamide into an aqueous solution, and carrying out ice bath treatment to obtain an AM/MBA mixed solution; then adding an ammonium persulfate aqueous solution into the AM/MBA mixed solution, and stirring to obtain a hydrogel solution;

and placing the aerogel in the hydrogel solution, heating for reaction, pre-freezing the reaction product, and freeze-drying to obtain the double-network aerogel.

2. The method of claim 1, wherein the impregnation temperature is 70-75 ℃ and the time is 40-50 hours.

3. The method according to claim 1, wherein the ratio of acrylamide, N-N' methylenebisacrylamide, and water is 4-6g:0.05-0.15g:40-50mL when the AM/MBA mixed solution is prepared.

4. The preparation method according to claim 1, wherein the mass ratio of the ammonium persulfate to the acrylamide is 1:20-1: 10.

5. The method according to claim 1, wherein the concentration of the aqueous solution of ammonium persulfate is 0.01-0.02 g/mL.

6. The method according to claim 1, wherein the heating reaction is carried out at a temperature of 40 to 60 ℃ for 20 to 40 min.

7. The preparation method according to claim 1, wherein the pre-freezing treatment is carried out at-18 to 24 ℃ for 4 to 5 hours; the temperature of the freeze drying is below minus 40 ℃, and the drying time is 18-24 h.

8. Double network aerogel obtainable by the preparation process according to any one of claims 1 to 7.

9. Use of the dual network aerogel of claim 8 as a dye wastewater decolorizing material.

Technical Field

The invention relates to the technical field of material preparation, in particular to a dual-network aerogel and a preparation method and application thereof.

Background

Most currently available adsorbent materials are aerogel materials and hydrogel materials. The aerogel is as adsorbing material, and the three key elements that very accord with ideal adsorbing material: the aerogel material has the defects of appropriate pore structure, large porosity and large specific surface area, but is relatively brittle, easy to break, difficult to store and the like. The hydrogel is a gel taking water as a dispersion medium, is a polymer network system, is soft in property, can keep a certain shape, can absorb a large amount of water, but is poor in stability and easy to degrade.

In order to improve the performance of gel materials, researchers in recent years provide many ideas, wherein the effect of preparing the double-network gel material is ideal, the performance of the material is improved, but the type of the existing double-network gel material is single, and the novel double-network gel material with good adsorption effect and good mechanical property and the preparation method thereof are provided, so that the variety of the gel material is enriched, and the technical problems to be solved at present are provided.

Disclosure of Invention

The invention aims to provide a double-network aerogel, and a preparation method and application thereof, so as to solve the problems in the prior art, ensure that the double-network aerogel has a more stable structure, and effectively reduce secondary pollution caused by dust release in the decoloring process of the traditional aerogel material.

In order to achieve the purpose, the invention provides the following scheme:

one of the technical schemes of the invention is to provide a preparation method of a double-network aerogel, which comprises the following steps:

soaking the wood in a mixed solution of glacial acetic acid and hydrogen peroxide, washing the soaked wood to be neutral, and freeze-drying after pre-freezing treatment to obtain aerogel;

preparing acrylamide and N-N' methylene bisacrylamide into an aqueous solution, and carrying out ice bath treatment to obtain an AM/MBA mixed solution; then adding an ammonium persulfate aqueous solution into the AM/MBA mixed solution, and stirring to obtain a hydrogel solution;

and placing the aerogel in the hydrogel solution, heating for reaction, pre-freezing the reaction product, and freeze-drying to obtain the double-network aerogel.

Furthermore, the dipping temperature is 70-75 ℃, and the time is 40-50 h.

Further, when preparing the AM/MBA mixed solution, the ratio of the acrylamide, the N-N' methylene-bis-acrylamide and the water is 4-6g:0.05-0.15g:40-50 mL.

Further, the mass ratio of the ammonium persulfate to the acrylamide is 1:20-1: 10.

Further, the concentration of the ammonium persulfate aqueous solution is 0.01-0.02 g/mL.

Further, the heating reaction temperature is 40-60 ℃, and the time is 20-40 min.

Further, the temperature of the pre-freezing treatment is-18-24 ℃, and the time is 4-5 hours; the freeze drying temperature is below-40 deg.C, and the time is 18-24 hr.

The second technical scheme of the invention provides the double-network aerogel obtained by the preparation method.

The third technical scheme of the invention is to provide the application of the double-network aerogel as a dye wastewater decoloring material.

The invention discloses the following technical effects:

according to the invention, the aerogel and the hydrogel are combined in the preparation process, the cellulose-based aerogel with anisotropy is prepared by adopting wood, lignin and hemicellulose in the wood are extracted on the premise of not damaging the original macroscopic structure of the wood, the anisotropic structures of the cellulose in the wood and the wood are retained, the porosity of the aerogel is increased, and then the hydrogel is loaded on the aerogel so as to improve the structural stability of the aerogel.

The double-network aerogel reduces secondary pollution of water caused by dust released in the process of decoloring traditional aerogels, meanwhile, the cellulose aerogel prepared from wood is green and pollution-free, the raw material source is wide, the cost is low, the structural stability is improved by combining with the hydrogel, and the double-network aerogel has a good effect on decoloring dye wastewater.

The preparation process of the double-network aerogel is simple, the holes of the used wood raw material are widely distributed, the advantages of two porous materials of wood and aerogel are combined, and the double-network aerogel is crosslinked with a hydrogel system, so that the defect that the aerogel material is high in brittleness and easy to recycle is overcome, and secondary pollution is reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a flow chart of the preparation of the dual-network aerogel of the present invention;

FIG. 2 is an SEM image of Salix psammophila wood of example 1;

FIG. 3 is an SEM image of a Salix psammophila aerogel of example 1;

FIG. 4 is an SEM image of a Salix psammophila dual-network aerogel prepared in example 1;

FIG. 5 is a pictorial view of the aerogel of Pinus sylvestris of example 2;

fig. 6 is an SEM image of pinus sylvestris double network aerogel of example 2.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The description and examples are intended to be illustrative only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

Example 1

(1) Preparing salix mongolica aerogel:

200mL of glacial acetic acid is added into 20g of Salix psammophila blocks to dissolve lignin and hemicellulose, and 200mL of hydrogen peroxide is added to prevent wood from yellowing and further dissolve out the remaining lignin. And (3) placing the mixed solution soaked with the salix mongolica blocks in an electric drum air drying box for soaking for 48 hours at the temperature of 70 ℃, pouring out the mixed solution in the beaker for replacing when the mixed solution is soaked for 24 hours, and then continuously soaking for 24 hours by adopting the mixed solution until the wood is completely white.

Taking out the wood completely, washing with deionized water until the pH value of the solution is close to neutral, pre-freezing the sample at-18 ℃ for 4h, and then freeze-drying at-70 ℃ for 24 h. The mass of the obtained aerogel sample is reduced by about 40 percent compared with that of the original wood sample, and the aerogel sample has certain resilience but larger integral brittleness.

(2) Preparation of hydrogels

Acrylamide (AM, analytically pure) is a monomer, N-N' Methylene Bisacrylamide (MBA) is a cross-linking agent, and ammonium persulfate (KPS, analytically pure) is an initiator;

5g of acrylamide and 0.1g of N-N' methylene bisacrylamide are mixed in 40mL of deionized water, and stirred in an ice water bath for 30min to obtain an AM/MBA mixed solution; 0.05g of ammonium persulfate is dissolved in 5mL of deionized water, then the solution is added into the AM/MBA mixed solution, and the stirring is continued for 30min, so that the hydrogel solution is obtained.

(3) Preparing the double-network aerogel: and (2) placing the salix mongolica aerogel prepared in the step (1) into the hydrogel solution prepared in the step (2), soaking for 30min to enable the aerogel sample to be fully soaked in the hydrogel solution, placing the sample into a water bath kettle, heating and reacting for 40min at 50 ℃, and enabling the cellulose network of the salix mongolica aerogel and the acrylamide/N-N' methylene bisacrylamide network to be crosslinked and interpenetrated. And (3) finally, pre-freezing the sample and then putting the sample into a freeze dryer, wherein the temperature and the time conditions are the same as those in the step (1), and taking out the sample to obtain the double-network aerogel.

The compression deformation test result shows that the aerogel without the hydrogel system has structural collapse when the compressive stress is 0.026 MPa; the defects that the structure of the double-network aerogel added with the hydrogel collapses when the compressive stress is 0.108MPa, the aerogel is easy to break and the pore structure collapses are improved.

Example 2

(1) Preparing the camphor seed pine aerogel:

taking pinus sylvestris blocks (the mass is about 20g) with the size of 2 x 2cm, adding 200mL of glacial acetic acid and 200mL of hydrogen peroxide, placing the mixed solution soaked with the pinus sylvestris blocks in an air-blowing drying oven for soaking for 48h, setting the temperature to be 70 ℃, continuing soaking for 24h by adopting the mixed solution when the mixed solution is soaked in a cup for 24h and becomes brownish red for liquid change, wherein the time for soaking is longer when the pinus sylvestris blocks extract lignin and hemicellulose, and the need of watching the color of the block and the color of the solution determines whether to change the liquid for the second time or prolong the soaking time.

And completely taking out the wood when the wood is completely whitened, washing the wood with deionized water until the pH value is close to neutral, pre-freezing the sample for 4h at the temperature of-18 ℃, and then freeze-drying the sample for 24h at the temperature of-70 ℃. The obtained camphor tree seed aerogel is looser and easy to collapse compared with the salix mongolica aerogel structure, has more pores and has the mass reduced by about 42 percent compared with the original wood.

(2) Preparation of hydrogels

Acrylamide (AM, analytically pure) is a monomer, N-N' Methylene Bisacrylamide (MBA) is a cross-linking agent, and ammonium persulfate (KPS, analytically pure) is an initiator;

5g of acrylamide and 0.1g of N-N' methylene bisacrylamide are mixed in 40mL of deionized water, and stirred in an ice water bath for 30min to obtain an AM/MBA mixed solution; 0.05g of ammonium persulfate is dissolved in 5mL of deionized water, then the solution is added into the AM/MBA mixed solution, and the stirring is continued for 30min to obtain the hydrogel solution.

(3) Preparing the double-network aerogel: and (2) placing the pinus sylvestris aerogel prepared in the step (1) into the hydrogel solution prepared in the step (2), soaking for 40min to fully soak the aerogel sample in the hydrogel solution, placing the sample into a water bath kettle, and heating and reacting for 40min at 50 ℃ to ensure that the cellulose network of the pinus sylvestris aerogel and the acrylamide/N-N' methylene bisacrylamide network are crosslinked and interpenetrated. And (3) finally, pre-freezing the sample and then putting the sample into a freeze dryer, wherein the temperature and time conditions are the same as those in the step (1), and taking out the sample to obtain the pinus sylvestris double-network aerogel.

The compression deformation test result shows that the camphor pine aerogel without the hydrogel system has structural collapse when the compressive stress is 0.027 MPa; the defects that the structure of the double-network aerogel added with the hydrogel collapses when the compressive stress is 0.114MPa, the aerogel is easy to break and the pore structure collapses are improved.

Adsorption performance of the double-network aerogel:

dye wastewater decolorization experiment

The Methylene Blue (MB) solution with the concentration of 100mg/L is prepared through experiments, and experimental data show that when the pH value of the MB solution is 5, the adsorption time is 120min, the temperature is 30 ℃, and the adding amount of the salix mongolica double-network aerogel prepared in example 1 is 1.2g, the decoloring rate of the salix mongolica double-network aerogel solution on the Methylene Blue (MB) solution is the highest and can reach 92.06%, and the decoloring rate of the salix mongolica aerogel on the Methylene Blue (MB) solution under the same conditions is 73.1%. The pinus sylvestris double-network aerogel prepared in example 2 was subjected to decolorization treatment on Methylene Blue (MB) solution under the same experimental conditions as in example 1, and the decolorization rate of the pinus sylvestris aerogel was 93.04%, and the decolorization capacity of the pinus sylvestris aerogel was also tested during the experiment, and the decolorization rate was 69%. Can directly take out double network aerogel after accomplishing MB solution decoloration processing, retrieve the convenience and reduced secondary pollution, and the aerogel has become loose at the decoloration in-process because structural stability is poor, causes to retrieve the difficulty. In conclusion, the double-network aerogel is remarkably improved in dye wastewater decolorization treatment and structural stability compared with the original aerogel.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.