Three-phase foam extinguishing agent with high stability and adhesion and preparation method thereof

Abstract

The invention discloses a three-phase foam extinguishing agent with high stability and adhesion and a preparation method of the three-phase foam extinguishing agent. The method comprises the following steps: firstly, preparing cellulose nanocrystals CNC; the preparation method comprises the following steps: firstly, preparing cellulose nanocrystals CNC, then carrying out hydrophobic modification on the obtained cellulose nanocrystals CNC to obtain H-CNC, finally adding alkyl glycoside APG and the obtained H-CNC into water, and carrying out magnetic stirring to obtain a mixed solution A, specifically, the mass fraction of alkyl glycoside APG is 0.6 wt%, and the mass fraction of H-CNC is 0.1-0.3 wt%; then, hydroxypropyl methyl cellulose HPMC is added, temperature gradient stirring and mixing are conducted through a magnetic stirring machine, and the mass fraction of HPMC is 0.6 wt%. According to the foam extinguishing agent prepared by the method, the adhesion of foam can be remarkably improved, the foam can be stably adsorbed on the surface of a combustible for a long time, and the purposes of isolating air and extinguishing fire by suffocation are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of fire-fighting supplies, and particularly relates to a three-phase foam fire extinguishing agent with high stability and adhesion and a preparation method thereof. Background Art

[0002] Foam fire extinguishing agents are currently the primary means of fire prevention and extinguishing. Their compactness and low density allow them to cover combustibles at various locations, even in complex terrain such as coal mine goafs, forming a stable foam blanket that isolates the air and suffocates the fire. Furthermore, the foam blanket effectively attenuates the thermal radiation of the flame onto the surface of the combustible material, thereby slowing or preventing the rate of fuel vaporization or pyrolysis and volatilization, making it difficult for combustion factors to enter the combustion zone and acting as a barrier. Furthermore, when exposed to high temperatures, the water in the foam rapidly vaporizes, absorbing heat from the surface of the combustible material, lowering the temperature and preventing the flame from reigniting. However, foam is a thermodynamically unstable system, especially traditional gas-liquid two-phase foams, which are difficult to stabilize. Gas-liquid two-phase foams are stabilized only by surfactants with low desorption energies (the desorption energy of a single surfactant molecule is only a few kBT). Surfactants are reversibly adsorbed at the gas-liquid interface and easily fall off, resulting in poor foam stabilization. Furthermore, surfactants have weak interconnectivity and water-holding capacity, leading to significant foam instability. Foams with poor stability and water-holding capacity are difficult to ensure effective accumulation and wrapping of burning materials, which will greatly reduce their fire prevention and fire extinguishing capabilities. Currently, the commonly used foam fire extinguishing agent is water-based film-forming foam fire extinguishing agent. During use, it can cover the surface of burning materials in complex terrain through the accumulation of foam, and form a stable water film that effectively isolates oxygen, thereby extinguishing the fire source. However, the two-phase foam produced by water-based film-forming foam fire extinguishing agent is only stabilized by surfactants. The foam has a short precipitation time, poor stability, and is easy to disappear. The foam also has a low viscosity. After being diluted by 1% to 6%, the viscosity of the foam mixture is basically the same as that of water. The foam formed is difficult to adsorb on the surface of combustible materials for a long time. The combustible materials are easily exposed to air again, causing the flame to reignite. Therefore, continuous spraying is required to maintain the fire extinguishing effect.

[0003] Research has shown that the desorption energy of solid particles is typically several orders of magnitude higher than that of surfactant molecules. Nanoparticles, in particular, have high surface energy and can irreversibly and spontaneously adsorb at the air-liquid interface, balancing interfacial tension. Therefore, attaching nanoparticles to the foam surface is not only easy to achieve but can also effectively improve the stability of traditional air-water two-phase foams. Furthermore, by subjecting nanoparticles to a certain degree of hydrophobic modification to obtain intermediate hydrophobic nanoparticles, intermediate hydrophobic materials can better adsorb at the foam air-liquid interface than hydrophilic and superhydrophobic materials, improving foam stabilization. Guo Siyao's team's research has shown that nanoparticle contact angles in the range of 60 to 90° can effectively stabilize foam. Tuan Tran's team has further concluded that, other conditions remaining unchanged, the closer the nanoparticle contact angle is to 90°, the greater its desorption energy, and the more stably the nanoparticles can adsorb at the foam air-liquid interface.

[0004] In summary, current foam fire extinguishing agents mainly cover burning materials through two-phase foam, and the foam has weak stability and poor adhesion. Therefore, it is necessary to develop a foam fire extinguishing agent with high stability and adhesion by introducing nanoparticles with a suitable contact angle and using a thickener. Summary of the Invention

[0005] In response to the above-mentioned problems, the present invention proposes a three-phase foam fire extinguishing agent with high stability and adhesion and a preparation method thereof, which can significantly improve the adhesion of the foam, facilitate the long-term and stable adsorption of the foam on the surface of the combustible material, and achieve the purpose of isolating the air and suffocating the fire.

[0006] The above purpose is achieved through the following technical solutions: The present invention first provides a three-phase foam fire extinguishing agent with high stability and adhesion and a preparation method thereof, the method comprising the following steps: S1. Preparation of Cellulose Nanocrystals (CNCs): Cotton straw was processed into cellulose nanocrystals (CNCs) by crushing and screening, mixed acid hydrolysis, and ultrasonic treatment. S2. The cellulose nanocrystals CNC obtained in step S1 are subjected to hydrophobic modification, specifically comprising the following sub-steps: S21. The lauric acid was added to ethanol and stirred until the lauric acid was completely dissolved to obtain a lauric acid ethanol solution, wherein the lauric acid content was 10 g / L; S22. A 2 wt% CNC suspension, a 30% H2O2 concentration, a 0.5 mol / L H2SO4 concentration, and FeSO4 were added to the lauric acid ethanol solution of S21 and stirred and mixed. The contents of each material in each liter of lauric acid ethanol solution were as follows: 250 g CNC suspension, 0.5 ml H2O2, 0.15 g FeSO4, and 30 ml H2SO4. S23. The product of step S22 was centrifuged for solid-liquid separation, and then anhydrous ethanol was added and shaken thoroughly, and then centrifuged again for solid-liquid separation. The operation was repeated three times to remove impurities to obtain hydrophobically modified CNC, referred to as H-CNC; S3. Preparation of foam fire extinguishing agent, specifically comprising the following sub-steps: S31. The alkyl glycoside APG and the H-CNC obtained in step S23 were added to water and stirred magnetically to obtain a mixed solution A, wherein the mass fraction of the alkyl glycoside was 0.6wt% and the mass fraction of H-CNC was 0.1~0.3wt%; S32. Add hydroxypropyl methylcellulose (HPMC) to the mixed solution A obtained in step S31, and stir and mix the mixture in a temperature gradient using a magnetic stirrer, wherein the mass fraction of HPMC is 0.6 wt%.

[0007] Furthermore, step S1 specifically includes the following sub-steps: S11 obtain cotton straw fiber powder, the natural cotton straw was crushed and sieved to obtain 100 mesh cotton straw fiber powder; S12 configuration of a mixed acid solution, 45ml of sulfuric acid and 15ml of hydrochloric acid were mixed and added with deionized water to a volume of 100ml to obtain a mixed acid solution, wherein the sulfuric acid concentration was 98% and the hydrochloric acid concentration was 36%; S13 using 2g cotton straw fiber powder was added to the mixed acid solution and stirred to obtain a cellulose acid hydrolysis solution; S14. Ultrasonic cleaning machine was used to treat the solution in step S13 for 10 h; S15. Neutralize the suspension after ultrasonic treatment and add an appropriate amount of alkaline solution to the suspension.

[0008] S16. The liquid portion of the solution neutralized in step S15 is removed by centrifugation, and deionized water is added to the obtained solid phase product, shaken and then centrifuged. This operation is repeated three times to obtain CNC; S17. Considering the agglomeration of the CNC obtained in step S16, a second ultrasonic treatment is required. Water is added to the CNC obtained in step S16 and the mixture is thoroughly shaken to obtain a CNC suspension with a mass fraction of 2 wt%. The suspension is then ultrasonically treated for 10 minutes using an ultrasonic cell disruptor. This is repeated three times with an interval of 15 minutes between each treatment to obtain a uniformly dispersed CNC suspension.

[0009] Furthermore, the stirring and mixing in step S22 is carried out at 50° C. for 8 hours.

[0010] Furthermore, the magnetic stirring in step S31 is carried out by using a magnetic stirrer for 30 minutes at a stirring temperature of 70°C.

[0011] Furthermore, the temperature gradient stirring and mixing in step S32 is specifically stirring at 70° C. for 30 minutes, and then continuing stirring at room temperature of 20±10° C. for 30 minutes.

[0012] The present invention also provides a three-phase foam fire extinguishing agent with high stability and adhesion, and the foam fire extinguishing agent is prepared by adopting the above method.

[0013] The beneficial effects of the present invention compared to the prior art are: 1. The addition of high molecular polymer HPMC can significantly improve the adhesion of foam, which is conducive to the long-term and stable adsorption of foam on the surface of combustible materials, achieving the purpose of isolating air and suffocating fire.

[0014] 2. Lauric acid was used to hydrophobically modify the hydrophilic CNC. The contact angle of the modified CNC could reach 82°, close to 90°. The hydrophobically modified CNC had higher desorption energy and could be more stably adsorbed at the foam gas-liquid interface, resulting in better foam stabilization effect.

[0015] 3. H-CNC can form connections with APG and HPMC through hydrogen bonding, filling the three-dimensional HPMC network in the foam film and forming a viscoelastic shell on the foam surface. The stability of the foam is significantly enhanced with the increase of H-CNC concentration, and the optimal stability time of the environmentally friendly foam fire extinguishing agent is increased by 11 times.

[0016] 4. The present invention provides a new type of high-efficiency fire extinguishing agent for fire prevention and fire extinguishing in complex terrains such as coal mine goafs. The preparation method of the fire extinguishing agent is simple, can be industrialized, and has considerable application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Scanning electron microscopy observation results and static contact angles of CNC and H-CNC used in the present invention; Figure 2 The adhesion test results of the foams prepared from the foam fire extinguishing agents of Comparative Examples 1-2 and Examples 1-3 are shown; Figure 3 Liquid separation half-life and foaming rate of foam prepared from the foam fire extinguishing agents of Comparative Examples 1-2 and Examples 1-3; Figure 4 Schematic diagram and actual picture of the experimental arrangement for suppressing coal combustion. DETAILED DESCRIPTION

[0018] With respect to the preparation method of the foam fire extinguishing agent of the present invention, Comparative Examples 1 to 2 and Examples 1 to 3 are listed. Among them, the foaming liquid in Comparative Example 1 is a pure APG solution, the thickener HPMC is added to Comparative Example 1, and the amount of H-CNC used in Examples 1 to 3 is changed. The effects of H-CNC and HPMC are further explained.

[0019] Comparative Example 1: S1. Preparation of foaming liquid: APG was added to water and stirred at 70°C for 90 min using a magnetic stirrer to obtain a common foaming liquid, wherein the mass fraction of APG was 0.6 wt%.

[0020] Comparative Example 2: S1. Preparation of foaming liquid: APG was added to water and stirred at 70°C for 30 min using a magnetic stirrer to obtain a common foaming liquid, wherein the mass fraction of APG was 0.6 wt%.

[0021] S2. Thickener Usage: HPMC was added to the ordinary foaming liquid in S1 and stirred at 70°C for 30 minutes using a magnetic stirrer. Stirring was then continued at room temperature (20±5°C) for 30 minutes to obtain a thickening foaming agent, wherein the mass fraction of HPMC was 0.6 wt%. Example

[0022] S1. Acid hydrolysis treatment: First, natural cotton straw floccules were dried in an electric blast oven at 60°C until their mass remained unchanged. After removal, they were crushed using a multifunctional high-speed grinder and sieved through a 100-mesh sieve to obtain cotton straw fiber powder. A mixed acid solution was then prepared, with sulfuric acid and hydrochloric acid concentrations of 95 wt% and 36 wt%, respectively. 45 ml of sulfuric acid and 15 ml of hydrochloric acid were mixed and the volume was adjusted to 100 ml with deionized water. To this mixed acid solution, 2 g of cotton straw fiber powder was slowly added and stirred to obtain a cellulose acid hydrolysis solution. S2. CNC preparation: First, the solution described in step S1 was ultrasonically treated using an ultrasonic cleaning machine for 8 hours, and then the suspension after ultrasonic treatment was neutralized. The neutralized solid phase product was further washed to remove the liquid phase in the suspension. Deionized water was added and shaken, and then centrifuged. This operation was repeated 3 times to obtain solid phase A. Considering the agglomeration of CNC in solid phase A, it was necessary to perform a second ultrasonic treatment on it. Then, solid phase A was added to water at a mass ratio of 1:50 and shaken thoroughly. It was then ultrasonically treated again using an ultrasonic cell disruptor. The total ultrasonic time was 30 minutes, and it was completed three times with an interval of 15 minutes each time. Finally, a CNC suspension with a mass fraction of 2% was obtained. S3. Hydrophobic modification of CNC: First, lauric acid was added to ethanol and stirred thoroughly until the lauric acid was completely dissolved, yielding a lauric acid ethanol solution containing 10 g / L of lauric acid. The CNC suspension obtained in step S2, 30% H₂O₂, FeSO₄, and 0.5 mol / L H₂SO₄ were then added sequentially to the lauric acid ethanol solution and stirred at 50°C for 8 hours. The contents of each material per liter of the lauric acid ethanol solution were as follows: 250 g of CNC suspension, 0.5 ml of H₂O₂, 0.15 g of FeSO₄, and 30 ml of H₂SO₄. Finally, the mixture, after stirring for 8 hours, was centrifuged for solid-liquid separation. Ethanol was then added and shaken thoroughly, followed by another centrifuge for solid-liquid separation. This process was repeated three times to remove impurities, yielding hydrophobically modified CNC (H-CNC).

[0023] S4. Preparation of a fire extinguishing foam: APG and the H-CNC obtained in step S3 were added to water and stirred at 70°C for 30 minutes using a magnetic stirrer to obtain a foaming solution containing 0.6 wt % APG and 0.1 wt % H-CNC. HPMC was then added and stirred at 70°C for 30 minutes using a magnetic stirrer, followed by further stirring at room temperature (20 ± 5°C) for 30 minutes to obtain a fire extinguishing foam containing 0.6 wt % HPMC. Example

[0024] S1. Acid hydrolysis treatment: First, natural cotton straw floccules were dried in an electric blast oven at 60°C until their mass remained unchanged. After removal, they were crushed using a multifunctional high-speed grinder and sieved through a 100-mesh sieve to obtain cotton straw fiber powder. A mixed acid solution was then prepared, with sulfuric acid and hydrochloric acid concentrations of 95 wt% and 36 wt%, respectively. 45 ml of sulfuric acid and 15 ml of hydrochloric acid were mixed and the volume was adjusted to 100 ml with deionized water. To this mixed acid solution, 2 g of cotton straw fiber powder was slowly added and stirred to obtain a cellulose acid hydrolysis solution. S2. CNC preparation: First, the solution described in step S1 was ultrasonically treated using an ultrasonic cleaning machine for 8 hours, and then the suspension after ultrasonic treatment was neutralized. The neutralized solid phase product was further washed to remove the liquid phase in the suspension. Deionized water was added and shaken, and then centrifuged. This operation was repeated 3 times to obtain solid phase A. Considering the agglomeration of CNC in solid phase A, it was necessary to perform a second ultrasonic treatment on it. Then, solid phase A was added to water at a mass ratio of 1:50 and shaken thoroughly. It was then ultrasonically treated again using an ultrasonic cell disruptor. The total ultrasonic time was 30 minutes, and it was completed three times with an interval of 15 minutes each time. Finally, a CNC suspension with a mass fraction of 2% was obtained. S3. Hydrophobic modification of CNC: First, lauric acid was added to ethanol and stirred thoroughly until the lauric acid was completely dissolved, yielding a lauric acid ethanol solution containing 10 g / L of lauric acid. The CNC suspension obtained in step S2, 30% H₂O₂, FeSO₄, and 0.5 mol / L H₂SO₄ were then added sequentially to the lauric acid ethanol solution and stirred at 50°C for 8 hours. The contents of each material per liter of the lauric acid ethanol solution were as follows: 250 g of CNC suspension, 0.5 ml of H₂O₂, 0.15 g of FeSO₄, and 30 ml of H₂SO₄. Finally, the mixture, after stirring for 8 hours, was centrifuged for solid-liquid separation. Ethanol was then added and shaken thoroughly, followed by another centrifuge for solid-liquid separation. This process was repeated three times to remove impurities, yielding hydrophobically modified CNC (H-CNC).

[0025] S4. Preparation of a fire extinguishing foam: APG and the H-CNC obtained in step S3 were added to water and stirred at 70°C for 30 minutes using a magnetic stirrer to obtain a foaming solution containing 0.6 wt % APG and 0.2 wt % H-CNC. HPMC was then added and stirred at 70°C for 30 minutes using a magnetic stirrer, followed by further stirring at room temperature (20 ± 5°C) for 30 minutes to obtain a fire extinguishing foam containing 0.6 wt % HPMC. Example

[0026] S1. Acid hydrolysis treatment: First, natural cotton straw floccules were dried in an electric blast oven at 60°C until their mass remained unchanged. After removal, they were crushed using a multifunctional high-speed grinder and sieved through a 100-mesh sieve to obtain cotton straw fiber powder. A mixed acid solution was then prepared, with sulfuric acid and hydrochloric acid concentrations of 95 wt% and 36 wt%, respectively. 45 ml of sulfuric acid and 15 ml of hydrochloric acid were mixed and the volume was adjusted to 100 ml with deionized water. To this mixed acid solution, 2 g of cotton straw fiber powder was slowly added and stirred to obtain a cellulose acid hydrolysis solution. S2. CNC preparation: First, the solution described in step S1 was ultrasonically treated using an ultrasonic cleaning machine for 8 hours, and then the suspension after ultrasonic treatment was neutralized. The neutralized solid phase product was further washed to remove the liquid phase in the suspension. Deionized water was added and shaken, and then centrifuged. This operation was repeated 3 times to obtain solid phase A. Considering the agglomeration of CNC in solid phase A, it was necessary to perform a second ultrasonic treatment on it. Then, solid phase A was added to water at a mass ratio of 1:50 and shaken thoroughly. It was then ultrasonically treated again using an ultrasonic cell disruptor. The total ultrasonic time was 30 minutes, and it was completed three times with an interval of 15 minutes each time. Finally, a CNC suspension with a mass fraction of 2% was obtained. S3. Hydrophobic modification of CNC: First, lauric acid was added to ethanol and stirred thoroughly until the lauric acid was completely dissolved, yielding a lauric acid ethanol solution containing 10 g / L of lauric acid. The CNC suspension obtained in step S2, 30% H₂O₂, FeSO₄, and 0.5 mol / L H₂SO₄ were then added sequentially to the lauric acid ethanol solution and stirred at 50°C for 8 hours. The contents of each material per liter of the lauric acid ethanol solution were as follows: 250 g of CNC suspension, 0.5 ml of H₂O₂, 0.15 g of FeSO₄, and 30 ml of H₂SO₄. Finally, the mixture, after stirring for 8 hours, was centrifuged for solid-liquid separation. Ethanol was then added and shaken thoroughly, followed by another centrifuge for solid-liquid separation. This process was repeated three times to remove impurities, yielding hydrophobically modified CNC (H-CNC).

[0027] S4. Preparation of a fire extinguishing foam: APG and the H-CNC obtained in step S3 were added to water and stirred at 70°C for 30 minutes using a magnetic stirrer to obtain a foaming solution containing 0.6 wt % APG and 0.3 wt % H-CNC. HPMC was then added and stirred at 70°C for 30 minutes using a magnetic stirrer, followed by further stirring at room temperature (20 ± 5°C) for 30 minutes to obtain a fire extinguishing foam containing 0.6 wt % HPMC.

[0028] The electron microscope observation results and static contact angles of CNC and H-CNC involved in Examples 1 to 3 are shown in Figure 1 It can be seen that after hydrophobic modification, the particle size of CNC can still be maintained within 100 nm, and the particle size is uniform, which belongs to nanoparticles. Secondly, after hydrophobic modification, the contact angle of CNC is increased from 52° to 82°, and it is modified from hydrophilic nanoparticles to intermediate hydrophobic nanoparticles. Intermediate hydrophobic nanoparticles can be more stably adsorbed on the foam gas-liquid interface.

[0029] Adhesion and stability tests were conducted on the foams obtained in Comparative Examples 1-2 and Examples 1-3, respectively. The experimental steps for different groups of foams were the same. Adhesion test: The foam was poured into a culture dish with a diameter of 8.5 cm, and the culture dish was inverted to observe the sinking of the foam inside the container within 5 minutes. The experimental results are shown in Figure 2 Analysis of foam stability and foaming properties: Pour the foam into a glass measuring cylinder with a diameter of 5 cm, record the foam volume and the time required for the foam to precipitate half of its liquid, which are recorded as the foam expansion rate and the precipitation half-life. The analysis results are shown in Figure 3 .

[0030] Select comparative examples 1-2 and example 3, and the foam obtained is used to carry out the fire extinguishing and coal combustion inhibition experiment: Figure 4It is a simple model of a coal goaf. A porous plate is set inside the platform at a distance of 50 mm from the ground. The foam enters the coal pile from bottom to top through the porous plate. In order to understand the temperature changes of the coal pile in real time, a temperature sensing rod is inserted into the middle of the coal pile. The other end of the temperature sensing rod is connected to a temperature recorder. The temperature recorder displays the temperature of the coal pile at the corresponding position of the temperature sensing rod in real time. The foaming liquid of each embodiment is added to the foam generator respectively, and the foam generator is connected to the air compressor. After the experiment starts, the air generated by the air compressor drives the foam generator to generate foam. The foam passes through the porous plate from bottom to top through the injection pipe and enters the burning coal pile. After observing until the foam completely covers the coal pile, turn on the stopwatch and record the temperature of the middle of the coal pile before the fire is extinguished, 10 minutes after the fire is extinguished, 20 minutes after the fire is extinguished, and 30 minutes after the fire is extinguished. The experimental results are shown in Table 1.

[0031] like Figure 2 As shown, Comparative Example 1 is a foaming liquid without the thickener HPMC, and its foam has poor adhesion. When the container with the foam is turned upside down, the foam immediately slides down, and under the action of gravity, the part that is separated from the container wall continues to increase. Comparative Example 2 and Examples 1 to 3 are foaming liquids with the thickener HPMC added. Their foam has strong adhesion. When the container with these foams is turned upside down, the adhesion of the foam is significantly enhanced, and it can be stably adsorbed on the container wall without detaching. Moreover, with the increase of H-CNC content, the adhesion of the foam is also improved. In actual fire extinguishing applications, it is beneficial for the fire extinguishing foam to stably cover the burning object, completely expel the air, and achieve the effect of suffocating the fire. Figure 3 As shown, both Comparative Example 2 and Examples 1 to 3 added thickeners. The addition of thickeners reduced the foam expansion ratio of the foam to a certain extent, but the foam expansion ratio of the foam was still maintained at more than 8 times, meeting the foam extinguishing agent foaming ratio requirement. From the perspective of foam stability, the foam liquid separation half-life obtained by the foaming agents of Examples 1 to 3 was significantly improved compared to Comparative Examples 1 and 2, and the degree of increase increased with the increase of H-CNC content. The foam liquid separation half-life continued to increase. When the CNC content was 0.3wt%, the foam liquid separation half-life was optimal, reaching 930min, which was about 72 times higher than that of Comparative Example 1 and about 3 times higher than that of Comparative Example 2. Therefore, the APG / H-CNC / HPMC composite foaming agent used in the present invention can greatly improve the stability of the foam while ensuring the foam expansion ratio.

[0032] Table 1 shows the temperature changes at different times in the middle of the coal pile during the coal combustion experiment using the foams of Comparative Examples 1-2 and Example 3. It can be seen that 10 minutes after the coal fire was extinguished using only the foam of Comparative Example 1 or Comparative Example 2, the coal temperature dropped significantly. However, 20 minutes after the fire was extinguished, the temperature of the coal pile began to rise continuously. Half an hour after the fire was extinguished, the temperature exceeded 200°C. The main reason for this is that the stability and water holding capacity of the foams of Comparative Examples 1 and 2 are still poor, and their high temperature resistance is poor. They cannot completely cover the coal pile for a long time to achieve the purpose of isolating oxygen. On the contrary, half an hour after the fire was extinguished using the foam of Example 3, the foam temperature dropped to 33.7°C, close to room temperature, and effectively achieved fire extinguishing and cooling effects.

[0033] Table 1 Results of coal combustion inhibition experiments Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for parts thereof. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention. Although the above describes the specific embodiments of the present invention, it does not limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solutions of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A three-phase foam fire extinguishing agent with high stability and adhesion and a preparation method thereof, characterized in that: The method comprises the following steps: S1. Preparation of Cellulose Nanocrystals (CNCs): Cotton straw was processed into cellulose nanocrystals (CNCs) by crushing and screening, mixed acid hydrolysis, and ultrasonic treatment. S2. The cellulose nanocrystals CNC obtained in step S1 are subjected to hydrophobic modification, specifically comprising the following sub-steps: S21. The lauric acid was added to ethanol and stirred until the lauric acid was completely dissolved to obtain a lauric acid ethanol solution, wherein the lauric acid content was 10 g / L; S22. A 2 wt% CNC suspension, a 30% H2O2 concentration, a 0.5 mol / L H2SO4 concentration, and FeSO4 were added to the lauric acid ethanol solution of S21 and stirred and mixed. The contents of each material in each liter of lauric acid ethanol solution were as follows: 250 g CNC suspension, 0.5 ml H2O2, 0.15 g FeSO4, and 30 ml H2SO4. S23. The product of step S22 was centrifuged for solid-liquid separation, and then anhydrous ethanol was added and shaken thoroughly, and then centrifuged again for solid-liquid separation. The operation was repeated three times to remove impurities to obtain hydrophobically modified CNC, referred to as H-CNC; S3. Preparation of foam fire extinguishing agent, specifically comprising the following sub-steps: S31. The alkyl glycoside APG and the H-CNC obtained in step S23 were added to water and stirred magnetically to obtain a mixed solution A, wherein the mass fraction of the alkyl glycoside was 0.6wt% and the mass fraction of H-CNC was 0.1~0.3wt%; S32. Add hydroxypropyl methylcellulose (HPMC) to the mixed solution A obtained in step S31, and stir and mix the mixture in a temperature gradient using a magnetic stirrer, wherein the mass fraction of HPMC is 0.6 wt%.

2. The three-phase foam fire extinguishing agent with high stability and adhesion and its preparation method according to claim 1, characterized in that: Step S1 specifically includes the following sub-steps: S11 obtain cotton straw fiber powder, the natural cotton straw was crushed and sieved to obtain 100 mesh cotton straw fiber powder; S12 configuration of a mixed acid solution, 45ml of sulfuric acid and 15ml of hydrochloric acid were mixed and added with deionized water to a volume of 100ml to obtain a mixed acid solution, wherein the sulfuric acid concentration was 98% and the hydrochloric acid concentration was 36%; S13 using 2g cotton straw fiber powder was added to the mixed acid solution and stirred to obtain a cellulose acid hydrolysis solution; S14. Ultrasonic cleaning machine was used to ultrasonically treat the solution in step S13 for 10 h; S15. The suspension after ultrasonic treatment is neutralized, and an appropriate amount of alkaline solution is added to the suspension; S16. The liquid portion of the solution neutralized in step S15 is removed by centrifugation, and deionized water is added to the obtained solid phase product, shaken and then centrifuged. This operation is repeated three times to obtain CNC; S17. Considering the agglomeration of the CNC obtained in step S16, a second ultrasonic treatment is required. Water is added to the CNC obtained in step S16 and the mixture is thoroughly shaken to obtain a CNC suspension with a mass fraction of 2 wt%. The suspension is then ultrasonically treated for 10 minutes using an ultrasonic cell disruptor. This is repeated three times with an interval of 15 minutes between each treatment to obtain a uniformly dispersed CNC suspension.

3. The three-phase foam fire extinguishing agent with high stability and adhesion and its preparation method according to claim 1, characterized in that: The stirring and mixing in step S22 is carried out at 50° C. for 8 hours.

4. The three-phase foam fire extinguishing agent with high stability and adhesion and its preparation method according to claim 1, characterized in that: The magnetic stirring in step S31 is performed by using a magnetic stirrer for 30 minutes at a stirring temperature of 70°C.

5. The three-phase foam fire extinguishing agent with high stability and adhesion and its preparation method according to claim 1, characterized in that: The temperature gradient stirring and mixing in step S32 is specifically stirring at 70° C. for 30 min, and then stirring at room temperature of 20±10° C. for another 30 min.

6. A three-phase foam fire extinguishing agent with high stability and adhesion, characterized in that: The foam fire extinguishing agent is prepared by the method according to any one of claims 1 to 5.

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