CN113621102A

CN113621102A - Tea polyphenol/vitamin E synergistic antioxidant gel, preparation method and application

Info

Publication number: CN113621102A
Application number: CN202111026361.XA
Authority: CN
Inventors: 黄志安; 王宏升; 宋东鸿; 高玉坤; 尹义超; 张英华; 权赛南; 郭禛
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 2021-09-02
Filing date: 2021-09-02
Publication date: 2021-11-09

Abstract

The invention provides tea polyphenol/vitamin E synergistic antioxidant gel, a preparation method and application, and belongs to the technical field of antioxidant gel preparation. The invention utilizes the synergistic antioxidation between tea polyphenol and vitamin E to improve the antioxidation capability of the inhibitor, the antioxidant tea polyphenol and the vitamin E are grafted on the branched chain of the sodium polyacrylate through the graft polymerization, so that the antioxidant is well combined with the gel, the problem of incomplete inhibition effect of a single physical or chemical inhibitor is solved through the complementary advantages of the antioxidant tea polyphenol, the vitamin E and the gel, the heat dissipation problem urgently needed by the chemical inhibitor is solved, the application range of the inhibitor is expanded, the use cost of the inhibitor is reduced, and the efficient, green and economic coal mine spontaneous combustion prevention and control are hopefully realized.

Description

Tea polyphenol/vitamin E synergistic antioxidant gel, preparation method and application

Technical Field

The invention relates to the technical field of antioxidant gel preparation, and particularly relates to tea polyphenol/vitamin E synergistic antioxidant gel, a preparation method and application.

Background

In the work of inhibiting the spontaneous combustion of coal mines, stopping agents are mainly applied and mainly comprise chemical stopping agents, physical stopping agents and composite stopping agents, but various stopping agents still have some defects at present and are not solved.

The physical inhibitor can absorb moisture in the air to form a film to cover the coal body, and the effect of preventing and controlling the spontaneous combustion of the coal is realized by isolating the vaporization heat absorption and temperature reduction of the air and the water. However, the physical stopping agent is only started from the external environment and conditions, and cannot change the molecular structure of the coal, so that the problem of spontaneous combustion of the coal cannot be fundamentally solved. In practical application, the physical stopping agent has the problems of easy loss, short stopping time and the like, and the stopping agent needs to be regularly sprayed and timely supplemented, so that the maintenance cost is higher.

The chemical inhibitor can be combined with active groups in the coal free radical chain reaction to generate a stable product, and the effect of preventing and controlling the spontaneous combustion of the coal is realized by reducing the oxidation activity of the chemical inhibitor and interrupting the free radical chain reaction. However, when the stopping agent reacts with coal, the stopping agent also generates heat effect, and if the stopping agent cannot dissipate heat in time, the temperature of the coal body is increased, and even spontaneous combustion can be caused. In addition, the storage and transportation of strong oxidants require special conditions, such as improper disposal, which is very dangerous. And different types of coal have different molecular structures, even show obvious difference, and some coal spontaneous combustion stopping agents only can have a stopping effect on one or more types of coal, so that the chemical stopping agents often have specificity. In addition, the chemical stopping agent has higher cost, and the economic efficiency of directly applying the chemical stopping agent to coal mine stopping is poor.

The tea polyphenol and the vitamin E are common natural antioxidants, and after the two antioxidants are compounded in a certain proportion, a synergistic effect can be formed, so that the effect of the antioxidants is greatly enhanced. However, the research on the synergistic antioxidant effect of tea polyphenol and vitamin E is frequently found in the fields of food, medicine, health care and the like, and the research on the inhibition of coal mines is less.

Because the inhibition of coal is essentially an antioxidant effect, antioxidants can be used to inhibit spontaneous combustion in coal mines, but antioxidants are prone to losing their antioxidant effect at high temperatures due to decomposition or deterioration, and the problem of heat generation from the reaction of antioxidants with coal also needs to be solved.

Disclosure of Invention

In view of the above, the invention provides a preparation method of tea polyphenol/vitamin E synergistic antioxidant gel, which overcomes the problem of incomplete inhibition effect of a single physical or chemical inhibitor by complementing the advantages of the antioxidant tea polyphenol and vitamin E with the gel, solves the problem of heat dissipation urgently needed by the chemical inhibitor, enlarges the application range of the inhibitor, reduces the use cost of the inhibitor, and is expected to realize efficient, green and economic coal mine spontaneous combustion prevention and control.

The preparation method of the tea polyphenol/vitamin E synergistic antioxidant gel provided by the invention comprises the following steps:

1) neutralizing the acrylic acid aqueous solution and the sodium hydroxide aqueous solution in an ice water bath to obtain a sodium acrylate aqueous solution with the neutralization degree of 75-85%;

2) mixing tea polyphenol and vitamin E according to the mass ratio of 1:0.04-1:0.05, and dissolving in water to obtain a tea polyphenol and vitamin E mixed aqueous solution;

3) adding the mixed aqueous solution of tea polyphenol and vitamin E into the sodium acrylate aqueous solution neutralized in the step 1), wherein the mass ratio of the sum of the mass of the tea polyphenol and the vitamin E to the mass of acrylic acid is 2-3%, fully stirring, adding an initiator and a cross-linking agent after the solution reaction is finished, and uniformly mixing;

4) and (3) carrying out sealing graft polymerization reaction on the mixed solution obtained in the step 3) at the temperature of 70-90 ℃ for 2-3h, slightly stirring at the beginning of the polymerization reaction until the mixed solution is uniform and stable, and stopping stirring to obtain the tea polyphenol/vitamin E synergistic antioxidant gel.

Preferably, the concentration of the acrylic acid aqueous solution in the step 1) is 80-100%, and the mass concentration of the sodium hydroxide aqueous solution is 20-30%.

Preferably, the mass ratio of the mixture of tea polyphenol and vitamin E in the step 2) to water is 2-3%.

Preferably, the method for adding the initiator and the cross-linking agent in the step 3) comprises the steps of adding the initiator, fully stirring to initiate free radical reaction of the tea polyphenol sanitary element E, then adding the cross-linking agent, carrying out ultrasonic treatment on the solution for 1-3min by using an ultrasonic dispersion instrument, and fully stirring for 20-60 min by using a magnetic stirrer.

Preferably, the initiator in the step 3) is potassium persulfate.

Preferably, the amount of the initiator accounts for 1.5-2% of the mass of the acrylic acid.

Preferably, the crosslinking agent in step 3) is N, N' -methylene bisamide.

Preferably, the amount of the cross-linking agent is 0.5-2% of the mass of the acrylic acid.

The invention also provides the tea polyphenol/vitamin E synergistic antioxidant gel prepared by the preparation method.

The application method of the tea polyphenol/vitamin E synergistic antioxidant gel comprises the steps of washing the gel with deionized water, drying at 80 ℃, grinding to obtain gel powder, dissolving the gel powder in a proper amount of deionized water to obtain a composite gel stopping agent, mixing the gel stopping agent with raw coal, and drying to prepare a stopping coal sample.

Compared with the prior art, the invention has the following beneficial effects:

the invention utilizes the synergistic antioxidation between tea polyphenol and vitamin E to improve the antioxidation capability of the inhibitor, and grafts the antioxidant tea polyphenol and the vitamin E on the branched chain of the sodium polyacrylate through the graft polymerization, so that the antioxidant is well combined with the gel, the oxidation spontaneous combustion of the coal can be fundamentally prevented through the chemical inhibition performance of the antioxidant, and the oxidation of the coal can be delayed through the physical inhibition performance of the gel. The combination of the antioxidant and the gel enables the antioxidant to be uniformly combined with the coal, so that the reaction is stably carried out, the generation of heat caused by the reaction is slowed down, and meanwhile, the evaporation of water in the gel can carry away most of the heat generated by the reaction, thereby solving the heat dissipation problem of the chemical stopping agent. The cost of obtaining the gel is lower than that of the antioxidant, and the release of the antioxidant can be controlled after the gel is combined with the antioxidant, so that the volatilization, decomposition, deterioration and the like of the antioxidant are avoided, the utilization rate of the antioxidant is improved, and the use cost of the inhibitor is reduced.

Drawings

FIG. 1 is a thermogravimetric plot of a hindered coal sample of example 1;

FIG. 2 is a thermogravimetric plot of a raw coal sample of comparative example 1;

FIG. 3 is a three-dimensional infrared spectrum of in-situ diffuse reflection of a hindered coal sample in example 1;

FIG. 4 is an in-situ diffuse reflectance three-dimensional infrared spectrum of a raw coal sample of comparative example 1;

FIG. 5 is an infrared spectrum of a sample of the hindered coal of example 1 at various temperature points;

FIG. 6 is an infrared spectrum of a raw coal sample at various temperature points of comparative example 1;

FIG. 7 is an infrared fit image of the hindered coal sample of example 1 at time 0 min;

FIG. 8 is an infrared fit image of the hindered coal sample of example 1 at time 20 min;

FIG. 9 is an infrared fit image of the hindered coal sample of example 1 at time 40 min;

FIG. 10 is an infrared fit image of the hindered coal sample of example 1 at time 60 min;

FIG. 11 is an infrared fit image of the hindered coal sample of example 1 at 80 min;

FIG. 12 is an infrared fit image of the hindered coal sample of comparative example 1 at time 0 min;

FIG. 13 is an infrared fit image of the hindered coal sample of comparative example 1 at 20 min;

FIG. 14 is an infrared fit image of the hindered coal sample of comparative example 1 at 40 min;

FIG. 15 is an infrared fit image of the hindered coal sample of comparative example 1 at 60 min;

FIG. 16 is an IR fit image of the hindered coal sample of comparative example 1 at 80 min.

Detailed Description

The present invention will be further described with reference to the following examples.

Example 1

A preparation method of tea polyphenol/vitamin E synergistic antioxidant gel comprises the following steps:

(1) weighing 10g of acrylic acid solution to prepare 99% acrylic acid solution and 25% sodium hydroxide aqueous solution;

(2) neutralizing the acrylic acid aqueous solution and the sodium hydroxide aqueous solution in the step (1) in an ice-water bath to obtain an acrylic acid aqueous solution with the neutralization degree of 80%;

(3) weighing 228.6mg of tea polyphenol and 11.4mg of vitamin E (mass ratio is 1:0.05), mixing, and dissolving in 10g of water to obtain a tea polyphenol vitamin E solution;

(4) adding the tea polyphenol vitamin E solution prepared in the step (3) into the neutralized solution obtained in the step (2), fully stirring, and after the solution is reacted, adding 0.168g of potassium persulfate (KPS) into the neutralized solution, and fully stirring to initiate free radical reaction between the tea polyphenol and the vitamin E; then 0.1g of N, N' -Methylenebisacrylamide (MBA) was added, and the solution was sonicated for 2min using a sonicator and stirred well with a magnetic stirrer for 4 min.

(5) And (3) placing the solution obtained in the step (4) in a constant-temperature water bath at 85 ℃ for sealing, carrying out graft polymerization reaction for 3h, slightly stirring at the beginning of the polymerization reaction until the mixed solution is uniform and stable, and stopping stirring to obtain the tea polyphenol/vitamin E synergistic antioxidant gel.

And (3) washing the gel with deionized water, drying at 80 ℃, and grinding to obtain gel powder. 0.48g of gel powder is weighed and dissolved in 20ml of water to obtain a composite gel stopping agent, 2.5g of raw coal is added to be mixed and dried, and a stopping coal sample is prepared.

Comparative example 1

Raw coal without tea polyphenol/vitamin E synergistic antioxidant gel powder was used as a comparative example.

Experiment 1

Analyzing the characteristic temperature points of the coal samples of the example 1 and the comparative example 1 through a thermogravimetric experiment, comparing the characteristic temperature points and screening out the proportion with the best inhibition effect, wherein the experimental conditions are as follows: the air flow is 50ml/min, the heating rate is 10 ℃/min, and the temperature range is 30-800 ℃.

Wherein, the thermogravimetric curve of the coal sample for resisting the gasification in the example 1 is shown in figure 1, and the thermogravimetric curve of the coal sample for raw coal in the comparative example 1 is shown in figure 2.

According to the TG-DTG graphs of different samples in the figure 1 and the figure 2, the general change trends of TG and DTG curves are observed, and characteristic temperature points are marked by combining the reaction characteristics in the coal oxidation spontaneous combustion process, as shown in the table 1:

TABLE 1

As can be seen from Table 1, T of the gel inhibited coal sample₁The initial critical temperature point is 57.5 ℃ higher than that of the raw coal sample, T₂The acceleration temperature point is 258.2 ℃ higher than that of the raw coal sample, T₃The cracking temperature point is 133.1 ℃, is obviously higher than that of a raw coal sample, and T₄The active temperature point is 139.1 ℃ higher than that of the raw coal sample. Therefore, the inhibitor has good inhibition effect in the early and middle stages of the coal oxidation reaction, shortens the duration of the moisture evaporation and desorption stage and the oxygen absorption weight increasing stage of the coal oxidation reaction, reduces the adsorption amount of the coal to the oxygen, and further inhibits the progress of the oxidation reaction of the coal and the oxygen. The reason is analyzed, and the following aspects exist:

(1) the water-fixing performance is that more than 90% of the composition components in the undried gel are water, the dried gel has water absorption and can absorb water which easily flows in the coal body, and when the temperature of the coal body is raised, the temperature of the coal body is reduced through water volatilization, so that the physical effect of heat absorption and temperature reduction is achieved.

(2) The gel gelling is an endothermic reaction, when the temperature of the coal body rises, water in the gel is vaporized to absorb the heat of the coal body, and the effect of cooling is achieved.

Experiment 2

The hindered coal sample prepared in example 1 and the raw coal sample prepared in comparative example 1 are tested by a Fourier infrared diffuse reflection experiment, the obtained infrared absorption peak curve is subjected to peak-splitting fitting, the change of the content of functional groups of the raw coal sample and the hindered coal sample in the temperature rising process is analyzed, and the synergistic antioxidation mechanism of tea polyphenol and vitamin E is analyzed. The temperature rise time of the experiment temperature rise program is 140min, the temperature rise rate is set to be 5 ℃/min, the equipment is suspended when the temperature per liter is 20 ℃, and the equipment is kept stand for 5 min. Wherein, the three-dimensional infrared spectrogram of the diffuse reflection in situ of the stopping coal sample in the example 1 is shown in figure 3, and the three-dimensional infrared spectrogram of the diffuse reflection in situ of the raw coal sample in the comparative example 1 is shown in figure 4.

The infrared spectrograms at a plurality of temperature points (30 ℃ (0min), 180 ℃ (20min), 280 ℃ (40min), 380 ℃ (60min), 480 ℃ (80min)) are cut out from the in-situ diffuse reflection three-dimensional infrared spectrograms of fig. 3 and 4 at certain intervals, and subjected to peak separation fitting. The infrared spectrogram of the inhibition coal sample of the example 1 at each temperature point is shown in FIG. 5, and the infrared spectrogram of the raw coal sample of the comparative example 1 at each temperature point is shown in FIG. 6.

Peak fitting processing is carried out on the infrared spectrogram of the original coal sample and the inhibition coal sample at different time points by using peakfit software, and the C-C double bond C (C-C) and the methyl-CH double bond C (methyl-CH) in the fitted curve are calculated₃Peak areas of four functional groups of carboxyl-COOH and aldehyde-CHO are taken as reference values of the content of the functional groups.

Wherein, the infrared fitting images of the blocking coal sample of the embodiment 1 at the time of 0min, 20min, 40min, 60min and 80min are respectively shown in FIGS. 7 to 11; the infrared fitting images of the raw coal sample of comparative example 1 at the time of 0min, 20min, 40min, 60min, and 80min are shown in fig. 12 to 16, respectively.

The peak area calculation results of the hindered coal samples obtained from FIGS. 7 to 11 are shown in Table 2:

TABLE 2

The raw coal sample peak area calculations obtained from FIGS. 12-16 are shown in Table 3:

TABLE 3

As can be seen from tables 2 and 3:

(1) the carbon-carbon double bond content of the inhibition coal sample is in a fluctuation and decline situation with the temperature rise, but the content change is not obvious. When the reaction time is 20-60 min, the content of carbon-carbon double bonds is basically kept stable, and the carbon-carbon double bonds are less involved in the oxidation reaction of coal; the carbon-carbon double bonds of the raw coal fluctuate with the temperature rise, but the content is basically kept stable. At 0-20 min (30-130 ℃), the carbon-carbon triple bond in the coal molecule is subjected to a hydrogenation polymerization reaction to generate a carbon-carbon double bond, so that the content of the carbon-carbon double bond is increased. When the reaction time is 20-60 min, the carbon-carbon double bond content is basically kept stable, and the carbon-carbon double bond content is less in the temperature-rising oxidation reaction of coal. The carbon-carbon double bond content slightly rises when the time is 60-80 min.

(2) The methyl contents of the raw coal and the inhibition coal sample are in a state of firstly reducing and then increasing, and the methyl content of the inhibition coal sample at 30 ℃ (0min) is obviously higher than that of the raw coal at the same time point, which indicates that the inhibition coal sample contains more aromatic components; in the temperature range of 30-130 ℃ for 0-20 min, methyl participates in the coal oxidation reaction to generate long-chain aliphatic hydrocarbon, so that the content is obviously reduced; in the range of 20 min-40 min (130 ℃ -230 ℃), the methyl content is basically kept unchanged and does not participate in the oxidation reaction of coal; in the temperature range of 230-330 ℃ for 40-60 min, the methyl content is basically kept unchanged after being increased, and the long-chain aliphatic hydrocarbon in the coal is broken to generate new short-chain groups, so the methyl content is also increased continuously; after the temperature is higher than 330 ℃ (60min), the methyl content is basically kept unchanged and does not participate in the oxidation reaction of the coal any more.

As can be seen from the trend: the aliphatic hydrocarbon side chain methyl participates in a large amount of reaction with oxygen in the initial reaction stage, the content is rapidly reduced, and long chain groups are generated; in the middle reaction stage, the long chain groups generated by methyl are heated and decomposed into short chain groups along with the temperature rise, and the methyl content rises.

(3) The situation that the carboxyl content of the original coal sample is firstly reduced and then increased is that the small molecular chain carboxyl is heated and decomposed into CO within 0-20 min (30-130 ℃ temperature interval)₂、H₂The content of O is sharply reduced; the carboxyl content is basically kept stable within 20min to 40min (temperature range of 130 ℃ to 230 ℃); in the temperature range of between 40 and 60 minutes (between 230 and 330 ℃), along with the rise of the temperature, oxygen oxidizes aldehyde groups, aliphatic hydrocarbon and oxygen-containing groups to generate carboxyl, and the generation of peroxide is accompanied, so that the content of the carboxyl is increased rapidly; in the temperature range of 330-430 ℃ for 60-80 min, oxygen in the original coal sample continues to oxidize oxygen-containing groups, and the content of carboxyl groups slowly rises.

The initial carboxyl content of the inhibition coal sample is lower than that of the original coal sample, which shows that components in the inhibition agent react with carboxylic acid or aldehyde group to cause the balance movement of the chemical reaction of aldehyde group oxidized into carboxyl group, thereby reducing the contents of aldehyde group and carboxyl group; the conversion process present during the reaction is represented by formula (1):

when the temperature is between 30 and 130 ℃ for 0 to 20min, the carboxyl content of the raw coal is sharply reduced, the carboxyl and aldehyde groups participate in the oxidation reaction of the coal and are oxidized into CO2 and H2O by oxygen, and the carboxyl content is reduced; the carboxyl content in the inhibition coal sample is basically kept stable when the temperature is between 130 and 230 ℃ for 20 to 40 min; oxidizing oxygen-containing groups in the coal at high temperature by oxygen at the temperature of 230-330 ℃ for 40-60 min to generate carboxyl; when the temperature is between 330 and 430 ℃ for 60 to 80min, the modification of the inhibitor is ineffective, but the thermal decomposition reaction of the carboxyl is promoted, so that the content of the carboxyl is slightly reduced.

(4) The aldehyde group content of the raw coal sample is generally in a descending trend, and the aldehyde group and the carboxyl are oxidized by oxygen to generate CO when the temperature is between 0 and 20min (between 30 and 130℃)₂And H₂O, the content of aldehyde groups is reduced; when the temperature is between 130 and 230 ℃ for 20 to 40min, the contents of aldehyde groups and carboxyl groups are basically kept stable, and the aldehyde groups and the carboxyl groups do not participate in the oxidation reaction of coal in a large amount; when the temperature is between 230 and 330 ℃ for 40 to 60min, the hydroxyl of the raw coal sample is oxidized by oxygen, so that the carboxyl is raised, and the content of aldehyde group is kept stable; when the temperature is between 330 and 430 ℃ for 60 to 80min, oxygen oxidizes aldehyde groups and oxygen-containing groups in coal molecules, the content of aldehyde groups is reduced, and the content of carboxyl groups is increased.

The content of aldehyde groups in the inhibition coal sample is increased and then reduced, and a large amount of aldehyde groups are consumed by the inhibition agent, so that the content of aldehyde groups is low, and when the time is 0-20 min, oxygen inhibits the process of oxidizing the aldehyde groups by oxygen, and the generated carboxylic acid is decomposed by heating, so that the content of aldehyde groups is increased, and the content of carboxyl groups is reduced; the aldehyde group content of the inhibition coal sample is kept stable when the time is 20-40 min; when the time is 40-60 min, the aldehyde group content is kept stable, and the carboxyl group content is rapidly increased; and when the time is 60-80 min, the aldehyde group is oxidized by oxygen, and the content is reduced.

In conclusion, the tea polyphenol and the vitamin E have a synergistic antioxidant effect on spontaneous combustion of coal, and the analysis reason is as follows: the tea polyphenol structure contains abundant phenolic hydroxyl groups, has strong hydrogen supply capacity, and can remove various forms of free radicals, thereby interrupting the progress of oxidation reaction and inhibiting the generation of peroxide in the reaction; vitamin E, in which the phenolic ring hydrogen is released by resonance, supplies electrons to the free radicals, making them stable. The mechanism of the synergistic antioxidation of tea polyphenol and vitamin E is presumed as follows: the vitamin E has strong reducibility, and reacts with oxygen to generate semi-oxygen and deoxidized VE so as to reduce the oxygen concentration, thereby reducing the reaction rate of converting Tea Polyphenol (TP) into peroxide free radicals (TP-OO.); in addition, tea polyphenols can inhibit the decay of VE and regenerate it, so that both have synergistic antioxidant effect.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of tea polyphenol/vitamin E synergistic antioxidant gel is characterized by comprising the following steps:

1) neutralizing an acrylic acid aqueous solution and a sodium hydroxide aqueous solution in an ice water bath to obtain a sodium polyacrylate aqueous solution with the neutralization degree of 75-85%;

3) adding the mixed aqueous solution of tea polyphenol and vitamin E into the aqueous solution of sodium polyacrylate neutralized in the step 1), wherein the mass ratio of the sum of the mass of the tea polyphenol and the vitamin E to the mass of acrylic acid is 2-3%, fully stirring, adding an initiator and a cross-linking agent after the solution reaction is finished, and uniformly mixing;

4) carrying out sealing graft polymerization reaction on the mixed solution obtained in the step 3) at the temperature of 70-90 ℃ for 2-3h to obtain the tea polyphenol/vitamin E synergistic antioxidant gel.

2. The method for preparing the tea polyphenol/vitamin E synergistic antioxidant gel as claimed in claim 1, wherein the concentration of the acrylic acid aqueous solution in the step 1) is 80-100%, and the mass concentration of the sodium hydroxide aqueous solution is 20-30%.

3. The method for preparing the tea polyphenol/vitamin E synergistic antioxidant gel as claimed in claim 1, wherein the mass ratio of the mixture of the tea polyphenol and the vitamin E in the step 2) to water is 2-3%.

4. The method for preparing the tea polyphenol/vitamin E synergistic antioxidant gel as claimed in claim 1, wherein the initiator and the cross-linking agent are added in step 3) by fully stirring after the initiator is added, then adding the cross-linking agent, carrying out ultrasonic treatment on the solution for 1-3min by using an ultrasonic dispersion instrument, and fully stirring for 20-60 min by using a magnetic stirrer.

5. The method for preparing the tea polyphenol/vitamin E synergistic antioxidant gel as claimed in claim 1, wherein the initiator in the step 3) is potassium persulfate.

6. The method for preparing the tea polyphenol/vitamin E synergistic antioxidant gel as claimed in claim 5, wherein the amount of the initiator is 1.5-2% of the mass of the acrylic acid.

7. The method for preparing the tea polyphenol/vitamin E synergistic antioxidant gel as claimed in claim 1, wherein the cross-linking agent in step 3) is N, N' -methylenebisacrylamide.

8. The method for preparing the tea polyphenol/vitamin E synergistic antioxidant gel as claimed in claim 7, wherein the amount of the cross-linking agent is 0.5-2% of the mass of acrylic acid.

9. A tea polyphenol/vitamin E synergistic antioxidant gel, which is characterized by being prepared by the preparation method of any one of claims 1 to 7.

10. The use of the tea polyphenol/vitamin E synergistic antioxidant gel as claimed in claim 9, wherein the gel is cleaned with deionized water, dried at 80 ℃, ground to obtain gel powder, dissolved in an appropriate amount of deionized water to obtain a composite gel stopping agent, mixed with raw coal and dried to obtain a stopping coal sample.