Preparation method of gemini surfactant for aqueous film-forming foam extinguishing agent for lithium battery fire

Abstract

The invention provides a preparation method of a gemini surfactant for an aqueous film-forming foam extinguishing agent for lithium battery fire disasters, which specifically comprises the following steps: reacting imidazole with 1, 4-dibromobutane to generate an intermediate product, and reacting the intermediate product with 1H, 1H, 2H, 2H perfluorohexyl iodide to generate the gemini surfactant; the gemini surfactant, lauryl sodium sulfate, cocamidopropyl betaine, urea, butanediol, diethylene glycol monobutyl ether and water are prepared into an aqueous film-forming foam extinguishing agent, the aqueous film-forming foam extinguishing agent is used for lithium battery fire disasters, and the gemini surfactant contained in the system improves the performance of the extinguishing agent; the gemini surfactant has high surface activity and low critical micelle concentration, has the outstanding advantages of excellent water solubility, good environmental protection performance, good compatibility with other surfactants and the like, is applied to an aqueous film-forming foam extinguishing agent, and is beneficial to further improvement of the fire extinguishing performance of the aqueous film-forming foam extinguishing agent. Good application and popularization prospects are realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of aqueous film-forming foam extinguishing agents, and particularly relates to a preparation method of a gemini surfactant for an aqueous film-forming foam extinguishing agent for lithium battery fires. Background Art

[0002] An aqueous film-forming foam extinguishing agent is a water-based extinguishing agent that can quickly spread, wet, and isolate combustible substances on the surface of combustibles. The core component in the formula of an aqueous film-forming foam extinguishing agent is a surfactant, which can quickly reduce the surface tension of water to enhance the spreading and wetting properties of the extinguishing agent, and then cool down the combustibles and isolate oxygen to achieve the effect of fire suppression. Hydrocarbon surfactants and fluorocarbon surfactants are often used as the core components in the formula to regulate the overall performance of the extinguishing agent due to their good surface activity. Among them, fluorocarbon surfactants are widely used in aqueous film-forming foam extinguishing agents due to their outstanding characteristics of "three highs and two aversions" (high surface activity, high chemical stability, high thermal stability, and water and oil aversion).

[0003] However, with the improvement of environmental protection policies, long fluorocarbon chain surfactants represented by perfluorooctane sulfonyl compounds have been gradually prohibited from use in various countries due to their toxicity and bioaccumulation. In order to find substitutes for perfluorooctane sulfonyl compounds, scholars in various countries have been committed to developing new short fluorocarbon chain surfactants for application in aqueous film-forming foam extinguishing agents. Among them, Capstone 1157 developed by DuPont Company has been widely used in the aqueous film-forming foam extinguishing agent system and achieved good results. Further research found that Capstone 1157 contains six fluorine-containing carbon atoms in its molecular structure, and the surface tension of the system can be as low as 15 mN / m after being compounded with other surfactants, with excellent spreading and wetting properties. Jia et al. prepared a surfactant C4-Br with a quaternary ammonium ion at the hydrophilic end and 4 perfluorocarbon atoms at the hydrophobic end. The surface tension was as low as 16.58 mN / m after being compounded with CH3(CH2)5NaO3S, and it could quickly spread and wet on combustible liquids. Through ring-opening reaction and sulfonation reaction, Kang et al. prepared a series of short fluorocarbon chain surfactants with surface tensions as low as 15.7 - 22.8 mN / m, having the potential for application in the aqueous film-forming foam extinguishing agent system.

[0004] On the other hand, with the booming development of the new energy industry, the detection and prevention of lithium battery fires have also attracted more and more attention. Lithium battery fires present complex characteristics such as fast burning speed, high burning temperature, and easy reignition. Some studies have shown that aqueous film-forming foam extinguishing agents have a certain effect on suppressing lithium battery fires. Li Yi pointed out in his research that 3% aqueous film-forming foam extinguishing agent at a rate of 2.0 L / (min·m 2) The intensity supply for 47 s can effectively extinguish the fire of a 10 Ah lithium battery. However, in practical applications, 3% aqueous film-forming foam may not be able to effectively solve the problem of lithium battery reignition. Releasing 6% aqueous film-forming foam is expected to solve this problem. In addition, recent studies have shown that the foam fire extinguishing agent with surfactant F-500 as the core has a good extinguishing effect on lithium battery fires. F-500 has a unique chemical structure and can use the chemical coating effect of the foam to seal combustible gas molecules during fire extinguishing, achieving a good fire extinguishing effect.

[0005] In order to study the specific formula of the aqueous film-forming foam fire extinguishing agent for lithium battery fires, Chen Kai et al. used perfluorohexyl-based fluorocarbon surfactants as the core. The perfluorohexyl-based fluorocarbon surfactants contain six fluorine-containing carbon atoms, and the surface tension of the compound solution formed by compounding with sodium dodecyl sulfate can be as low as about 14 mN / m. The compound solution as a whole has good spreading and wetting properties, can quickly combine with combustibles and penetrate deep inside for cooling. On this basis, further compounding with foaming agents, antifreezing agents and cosolvents, the final aqueous film-forming foam exhibits good overall performance and can extinguish the open fire of a 25 Ah lithium-ion battery within 10 s.

[0006] As the core component of the above-mentioned aqueous film-forming foam fire extinguishing agent, perfluorohexyl-based fluorocarbon surfactants (C-6 type) are mainly used in the formula to reduce the surface tension of water and increase the wetting property of the system. Some studies have shown that as the fluorocarbon chain at the hydrophobic end of the fluorocarbon surfactant shortens, its bioaccumulation and toxicity gradually decrease. When the number of fluorine-containing carbon atoms ≤ 6, its toxicity and bioaccumulation decrease significantly; when the number of fluorine-containing carbon atoms ≤ 4, the surfactant basically has no short-term toxicity. Therefore, further shortening the hydrophobic chain length of fluorine-containing carbon atoms helps to further improve its environmental friendliness.

[0007] In terms of molecular chemical configuration, the existing fluorocarbon surfactants for aqueous film-forming foam mostly have a "single head and single tail" configuration with one hydrophilic end and one hydrophobic chain, and the configuration is relatively single, making it difficult to further improve the performance. It is urgent to develop new configuration fluorocarbon surfactants to further improve the overall performance of the foam fire extinguishing agent.

[0008] Based on the development trend that the shorter the hydrophobic chain of fluorocarbon surfactants for aqueous film-forming foam extinguishing agents, the more environmentally friendly, the aim is to develop fluorocarbon surfactants with shorter hydrophobic chains for aqueous film-forming foam extinguishing agents to extinguish lithium battery fires. At the same time, different from the "single-head single-tail" (one hydrophobic end and one hydrophobic chain) configuration of existing fluorocarbon surfactants, the present invention aims to invent a fluorocarbon surfactant with a "gemini" configuration to improve the macroscopic properties of aqueous film-forming foam extinguishing agents. Gemini surfactants have a lower critical micelle concentration while having higher surface activity. At the same time, gemini surfactants have outstanding advantages such as excellent water solubility, good environmental performance, and good compatibility with other surfactants. Applying them to aqueous film-forming foam extinguishing agents helps to further improve their fire extinguishing performance. Summary of the Invention

[0009] The present invention mainly overcomes the deficiencies in the prior art and provides a preparation method of a gemini surfactant for aqueous film-forming foam extinguishing agents for lithium battery fires, specifically: first, react imidazole with 1,4-dibromobutane to generate an intermediate product, and then react the intermediate product with 1H,1H,2H,2H-perfluorohexyl iodide to generate the final gemini surfactant; this kind of gemini surfactant, sodium dodecyl sulfate, coconut oil amide propyl betaine, urea, butanediol, diethylene glycol monobutyl ether and water are formulated into an aqueous film-forming foam extinguishing agent. This aqueous film-forming foam extinguishing agent is used for lithium battery fires. The gemini surfactant contained in the system improves the performance of the extinguishing agent. It has a lower critical micelle concentration while having higher surface activity. The gemini surfactant of the present invention has outstanding advantages such as excellent water solubility, good environmental performance, and good compatibility with other surfactants. Applying it to aqueous film-forming foam extinguishing agents helps to further improve their fire extinguishing performance and has excellent application and promotion prospects.

[0010] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0011] A preparation method of a gemini surfactant for aqueous film-forming foam extinguishing agents for lithium battery fires, comprising the following steps:

[0012] Step S1: Synthesis of intermediate product

[0013] In a reaction vessel, dissolve imidazole and NaOH in dimethyl sulfoxide; after heating and stirring the solution,

[0014] Drop 1,4-dibromobutane into the warm solution; under the action of stirring, continue to stir and react the mixture; after the reaction, filter the cooled obtained mixture to obtain a white precipitate; recrystallize the white precipitate to obtain a purified intermediate product;

[0015] Step S2: Synthesis of gemini surfactant

[0016] In a reaction vessel, 1H,1H,2H,2H - perfluorohexyl iodide was introduced into absolute ethanol and stirred until dissolved. After heating the 1H,1H,2H,2H - perfluorohexyl iodide solution, the intermediate product obtained in step S1, which was dissolved in absolute alcohol, was added dropwise to the 1H,1H,2H,2H - perfluorohexyl iodide solution, and the reaction was carried out under reflux. The mixture obtained after the reaction was rotary evaporated and then recrystallized to obtain the final product, which was the gemini surfactant for the aqueous film - forming foam extinguishing agent for lithium - battery fires.

[0017] Further, in step S1, the molar ratio of imidazole, NaOH, and 1,4 - dibromobutane is 0.11 - 0.12:0.1 - 0.15:0.05 - 0.06.

[0018] Further, in step S1, imidazole and NaOH were dissolved in dimethyl sulfoxide, and the solution was stirred at 60 °C for 1 hour; the dropping rate of 1,4 - dibromobutane was 2 - 6 seconds per drop.

[0019] Further, in step S1, under stirring, the mixture was continuously stirred and reacted at 60 - 70 °C for 3 - 6 hours; the white precipitate was recrystallized with deionized water; then the white crystals were further evaporated under a vacuum environment to obtain the purified intermediate product.

[0020] Further, in step S2, the molar ratio of 1H,1H,2H,2H - perfluorohexyl iodide to the intermediate product is 0.1 - 0.12:0.05.

[0021] Further, in step S2, the 1H,1H,2H,2H - perfluorohexyl iodide solution was heated to 75 - 80 °C; the dropping rate of the intermediate product was 2 - 6 seconds per drop.

[0022] Further, in step S2, the reflux reaction was carried out for 20 h - 30 h.

[0023] Further, in step S2, after the mixture obtained after the reaction was rotary evaporated at 60 °C for 1 hour, it was recrystallized with ethyl acetate to obtain the final product.

[0024] Further, the aqueous film - forming foam extinguishing agent includes: 3 wt% of the gemini surfactant, 1 - 1.5 wt% of sodium dodecyl sulfate, 9 - 11 wt% of cocoamidopropyl betaine, 8 - 10 wt% of urea, 3 - 5 wt% of butanediol, 3 - 5 wt% of diethylene glycol monobutyl ether, and 65 - 75 wt% of water.

[0025] Further, the preparation method is as follows:

[0026] At 25 °C, successively add 3 wt% of gemini surfactant, 1 - 1.5 wt% of sodium dodecyl sulfate, 9 - 11 wt% of cocoamidopropyl betaine, 8 - 10 wt% of urea, 3 - 5 wt% of butanediol, 3 - 5 wt% of diethylene glycol monobutyl ether, and 65 - 75 wt% of water by mass fraction. After stirring evenly, it becomes the aqueous film-forming foam fire extinguishing agent.

[0027] Beneficial effects

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] The present invention provides a preparation method of a gemini surfactant for an aqueous film-forming foam fire extinguishing agent for lithium battery fires. Specifically: first, react imidazole with 1,4-dibromobutane to generate an intermediate product, and then react the intermediate product with 1H,1H,2H,2H-perfluorohexyl iodide to generate the gemini surfactant; this gemini surfactant, sodium dodecyl sulfate, cocoamidopropyl betaine, urea, butanediol, diethylene glycol monobutyl ether, and water are formulated into an aqueous film-forming foam fire extinguishing agent. This aqueous film-forming foam fire extinguishing agent is used for lithium battery fires. The gemini surfactant contained in the system improves the performance of the fire extinguishing agent, which is different from the "single head and single tail" (one hydrophobic end and one hydrophobic chain) configuration of the existing fluorocarbon surfactant; while having high surface activity, it has a low critical micelle concentration. The gemini surfactant of the present invention has outstanding advantages such as excellent water solubility, good environmental performance, and good compatibility with other surfactants. Applying it to the aqueous film-forming foam fire extinguishing agent helps to further improve its fire extinguishing performance and has excellent application and promotion prospects. Description of the drawings

[0030] Figure 1 It is the synthesis route diagram of the intermediate product BI-4 in the embodiment of the present invention;

[0031] Figure 2 It is the synthesis route diagram of the GS-im gemini surfactant in the embodiment of the present invention;

[0032] Figure 3 It is the infrared spectrum diagram of the GS-im gemini surfactant in the embodiment of the present invention;

[0033] Figure 4 It is the mass spectrum diagram of the GS-im gemini surfactant in the embodiment of the present invention;

[0034] Figure 5 It is the change rule diagram of the surface tension of the GS-im with the concentration in the embodiment of the present invention. Detailed implementation manners

[0035] To make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0036] According to Figure 1 and Figure 2 the synthetic route diagram shown, synthesize the gemini surfactants in the following examples.

[0037] Example 1: Synthesis of fluorocarbon gemini surfactant

[0038] Step 1: Synthesis of intermediate BI-4

[0039] As Figure 1 shown, in a 100 mL three-necked flask, dissolve 0.11 mol of imidazole and 0.1 mol of NaOH in 22 mL of dimethyl sulfoxide; after stirring the solution at 60 °C for 1 hour, add 0.05 mol of 1,4-dibromobutane dropwise to the warm solution at a rate of 4 drops per second; under stirring, the mixture is continuously stirred at 60 °C for 5 hours; after the reaction, filter the cooled obtained mixture to obtain a white precipitate. Recrystallize with 30 mL of deionized water; then further evaporate the white crystals under vacuum to obtain the purified intermediate BI-4.

[0040] Step 2: Synthesis of gemini surfactant GS-im

[0041] As Figure 2 shown, in a 100 mL three-necked flask, introduce 0.1 mol of 1H, 1H, 2H, 2H-perfluorohexyl iodide into 20 mL of anhydrous ethanol and stir to dissolve; at the same time, load 0.05 mol of BI-4 dissolved in 20 mL of absolute alcohol into a dropping funnel. After heating the 1H, 1H, 2H, 2H-perfluorohexyl iodide solution to 80 °C, add the BI-4 solution dropwise at a rate of 4 drops per second, and the reaction is carried out under reflux for 24 hours. After rotating and evaporating the reaction mixture at 60 °C for 1 hour, recrystallize with 20 mL of ethyl acetate to obtain the final product GS-im, which is the fluorocarbon gemini surfactant.

[0042] Example 2: Composition and preparation of aqueous film-forming foam extinguishing agent based on fluorocarbon gemini surfactant

[0043] The aqueous film-forming foam extinguishing agent based on fluorocarbon gemini surfactant includes: 3 wt% of gemini surfactant, 1 wt% of sodium dodecyl sulfate, 10 wt% of cocamidopropyl betaine, 9 wt% of urea, 4 wt% of butanediol, 4 wt% of diethylene glycol monobutyl ether and 69 wt% of water.

[0044] The preparation method of the aqueous film-forming foam fire extinguishing agent based on fluorocarbon gemini surfactant is as follows:

[0045] At 25 °C, 3% of fluorocarbon gemini surfactant GS-im, 1% of sodium dodecyl sulfate, 10% of cocamidopropyl betaine, 9% of urea, 4% of butanediol, 4% of diethylene glycol monobutyl ether and 69% of water are added in sequence by mass fraction. After stirring evenly, it is the aqueous film-forming foam fire extinguishing agent. And based on this, the overall performance of the aqueous film-forming foam fire extinguishing agent is tested.

[0046] Example 3: Evaluation of fluorocarbon gemini surfactant GS-im

[0047] Infrared spectrum and mass spectrum of GS-im:

[0048] The infrared spectrum of GS-im is as Figure 3 shown. The characteristic peaks at 2946 cm -1 and 2887 cm -1 are derived from the stretching vibration of the C-H bond in the methylene group (-CH2-) in the bridging structure of the GS-im gemini surfactant. 1228 cm -1 and 1133 cm -1 are respectively derived from the asymmetric stretching vibration and symmetric stretching vibration of the C-F bond in the hydrophobic end of the GS-im gemini surfactant bridge. In addition, the characteristic absorption peaks at 3094 cm -1 , 1569 cm -1 and 741 cm -1 are derived from the imidazole cation structure in the hydrophilic end of the S-im gemini surfactant. Thus, the bridging structure, two hydrophilic ends, and two hydrophobic chain structures of the GS-im gemini surfactant are characterized in the infrared spectrum.

[0049] The mass spectrum of the GS-im gemini surfactant is as Figure 4 shown. The molecular weight of GS-im is 938.0. The molecular weight of the cationic molecular fragment in its structure should be 684.2. However, due to its cationic structure containing two imidazole cation structures, the mass-to-charge ratio signal in the mass spectrum should be half of 684.2, that is, a signal peak appears at about 342.1, which is close to Figure 4 the measured 342.78 in

[0050] Surface tension test of GS-im:

[0051] The surface tension of the aqueous solution of the GS-im gemini surfactant is as Figure 5 shown. The data are summarized in Table 1. From Figure 5It can be seen that as the concentration of GS-im increases, the surface tension of water decreases significantly, enhancing the spreading and wetting properties of water and facilitating penetration into the interior of combustibles. The critical micelle concentration of GS-im is 0.86 mmol / L, and the surface tension at the critical micelle concentration is 18.7 mN / m, which is significantly lower than the surface tension of pure water (72.1 mN / m).

[0052] Table 1 Surface Tension at Different GS-im Concentrations

[0053] GS-im Concentration / mmol / L 0 0.2 0.4 0.6 0.8 1 1.2 1.4 Surface Tension / mN / m 72.1 37.2 26.8 22.7 20.6 18.7 18.7 18.7

[0054] Example 4: Evaluation of Aqueous Film-Forming Foam Extinguishing Agent Based on Fluorocarbon Gemini Surfactant

[0055] Overall Performance:

[0056] An aqueous film-forming foam extinguishing agent system with GS-im as the core component and compounded with other additives:

[0057] At 25 °C, add 3% of the fluorocarbon gemini surfactant GS-im, 1% of sodium dodecyl sulfate, 10% of coconut oil amide propyl betaine, 9% of urea, 4% of butanediol, 4% of diethylene glycol monobutyl ether, and 69% of water in sequence by mass fraction. After stirring evenly, it is the aqueous film-forming foam extinguishing agent.

[0058] The overall performance is shown in Table 2. It can be seen from Table 2 that this aqueous film-forming foam extinguishing agent system has a low surface tension, a moderate foaming multiple, can effectively extinguish lithium battery fires within 17 s, and has good application potential.

[0059] Table 2 Overall Performance of Aqueous Film-Forming Foam Extinguishing Agent with GS-im as the Core Component

[0060] Surface Tension Foaming Multiple pH Value Fire Extinguishing Test of 25Ah Lithium Battery 17.3 mN / m 9.1 8.56 Extinguished within 17 s and no reignition

[0061] In summary, the present invention provides a preparation method of a gemini surfactant for an aqueous film-forming foam extinguishing agent for lithium battery fires, specifically: first reacting imidazole with 1,4-dibromobutane to generate an intermediate product, and then reacting the intermediate product with 1H,1H,2H,2H-perfluorohexyl iodide to generate a gemini surfactant; this gemini surfactant, sodium dodecyl sulfate, coconut oil amide propyl betaine, urea, butanediol, diethylene glycol monobutyl ether, and water are formulated into an aqueous film-forming foam extinguishing agent. This aqueous film-forming foam extinguishing agent is used for lithium battery fires. The gemini surfactant contained in the system improves the performance of the extinguishing agent, has a high surface activity and a low critical micelle concentration at the same time. The gemini surfactant of the present invention has outstanding advantages such as excellent water solubility, good environmental performance, and good compatibility with other surfactants. Applying it to the aqueous film-forming foam extinguishing agent helps to further improve its fire extinguishing performance and has excellent application and promotion prospects.

[0062] Finally, it should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or apparatus comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or elements inherent to such process, method, article or apparatus.

[0063] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0064] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A preparation method of a gemini surfactant for an aqueous film-forming foam extinguishing agent against lithium battery fires, characterized in that, The preparation method includes the following steps: Step S1: Synthesis of intermediate product In a reaction vessel, imidazole and NaOH are dissolved in dimethyl sulfoxide; After heating and stirring the solution, 1,4-dibromobutane is added dropwise to the warm solution; under stirring, the mixture continues to stir and react; after the reaction, the cooled mixture is filtered to obtain a white precipitate; the white precipitate is recrystallized to obtain a purified intermediate product; Step S2: Synthesis of gemini surfactant In a reaction vessel, 1H,1H,2H,2H-perfluorohexyl iodide is introduced into absolute ethanol and stirred to dissolve; after heating the 1H,1H,2H,2H-perfluorohexyl iodide solution, the intermediate product obtained in Step S1 dissolved in absolute alcohol is added dropwise to the 1H,1H,2H,2H-perfluorohexyl iodide solution, and the reaction is carried out under reflux; the mixture obtained after the reaction is rotary evaporated and then recrystallized to obtain the final product, which is the gemini surfactant for the aqueous film-forming foam extinguishing agent for lithium battery fires.

2. The preparation method of the gemini surfactant for the aqueous film-forming foam extinguishing agent against lithium battery fire as described in claim 1, characterized in that, In Step S1, the molar ratio of imidazole, NaOH and 1,4-dibromobutane is 0.11 - 0.12:0.1 - 0.15:0.05 - 0.

06.

3. The preparation method of the gemini surfactant for the aqueous film-forming foam extinguishing agent against lithium battery fire as described in claim 1, characterized in that, In Step S1, imidazole and NaOH are dissolved in dimethyl sulfoxide, and the solution is stirred at 60 °C for 1 hour; the dropping rate of 1,4-dibromobutane is 2 - 6 seconds per drop.

4. The preparation method of a gemini surfactant for an aqueous film-forming foam extinguishing agent against lithium battery fires as described in claim 1, characterized in that, In Step S1, under stirring, the mixture continues to stir and react at 60 - 70 °C for 3 - 6 hours; the white precipitate is recrystallized with deionized water; then the white crystals are further evaporated under vacuum to obtain a purified intermediate product.

5. The preparation method of the gemini surfactant for the aqueous film-forming foam extinguishing agent against lithium battery fire as described in claim 1, characterized in that, In Step S2, the molar ratio of 1H,1H,2H,2H-perfluorohexyl iodide and the intermediate product is 0.1 - 0.12:0.

05.

6. The preparation method of the gemini surfactant for the aqueous film-forming foam extinguishing agent for lithium battery fires as described in claim 1, characterized in that, In Step S2, the 1H,1H,2H,2H-perfluorohexyl iodide solution is heated to 75 - 80 °C; the dropping rate of the intermediate product is 2 - 6 seconds per drop.

7. The preparation method of the gemini surfactant for the aqueous film-forming foam fire extinguishing agent for lithium battery fires as described in claim 1, characterized in that, In Step S2, the reflux reaction is carried out for 20 h - 30 h.

8. The preparation method of the gemini surfactant for the aqueous film-forming foam extinguishing agent for lithium battery fires as described in claim 1, characterized in that, In Step S2, the mixture obtained after the reaction is rotary evaporated at 60 °C for 1 hour and then recrystallized with ethyl acetate to obtain the final product.

9. An aqueous film-forming foam fire extinguishing agent based on the gemini surfactant described in any one of claims 1-8, characterized in that, The aqueous film-forming foam extinguishing agent includes: 3 wt% of gemini surfactant, 1 - 1.5 wt% of sodium dodecyl sulfate, 9 - 11 wt% of cocamidopropyl betaine, 8 - 10 wt% of urea, 3 - 5 wt% of butanediol, 3 - 5 wt% of diethylene glycol monobutyl ether and 65 - 75 wt% of water.

10. The preparation method of the aqueous film-forming foam fire extinguishing agent according to claim 9, characterized in that, The preparation method is as follows: At 25 °C, 3 wt% of gemini surfactant, 1 - 1.5 wt% of sodium dodecyl sulfate, 9 - 11 wt% of cocamidopropyl betaine, 8 - 10 wt% of urea, 3 - 5 wt% of butanediol, 3 - 5 wt% of diethylene glycol monobutyl ether and 65 - 75 wt% of water are added in sequence by mass fraction, and after stirring evenly, it is the aqueous film-forming foam extinguishing agent.

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