Aerogel foam fire extinguishing agent and in-situ preparation method thereof

Abstract

The invention discloses an aerogel foam fire extinguishing agent and an in-situ preparation method thereof. A template is first added to an ammonia-ethanol mixed solution and heated to dissolve, and then ethyl orthosilicate is added, and hydrolysis and condensation are performed under heating conditions to produce aerogel particles, and then a composite surfactant is added for surface adsorption modification and steric stabilization, and finally a fire extinguishing component is added to obtain an aerogel foam fire extinguishing agent. The preparation method of the aerogel foam fire extinguishing agent of the invention is simple, and there is no need to dry the aerogel particles and then mix and disperse them with the fire extinguishing liquid. The surface tension of the fire extinguishing liquid is greatly reduced under the condition of not containing pollutants such as PFOS, and the fire extinguishing and burning resistance of the foam is improved.

Description

Technical Field

[0001] The invention relates to the technical field of fire extinguishing materials, and in particular to an aerogel foam fire extinguishing agent and an in-situ preparation method thereof. Background Art

[0002] Foam fire extinguishing agent is the most commonly used and effective fire extinguishing agent for Class B fires. Foam fire extinguishing agents can be divided into aqueous film-forming foam fire extinguishing agent (AFFF), protein foam fire extinguishing agent 2 (P), synthetic foam fire extinguishing agent (S), etc. The spreadability, stability and burning resistance of foam on the surface of oil fire are crucial to the fire extinguishing efficiency of foam. In order to improve the stability and burning resistance of foam, solid particles can be added to the foam to form a gas-liquid-solid three-phase foam. After the bubbles are broken, the remaining solid particles are deposited on the surface of the lower foam. With the help of the heat insulation and burning resistance of solid particles and their synergistic effect with surfactants and polymers, the thermal stability and burning resistance of the three-phase foam are improved. Jiang Xinsheng's "Preparation and Stability Research of Compound Ultrafine Powder Three-Phase Foam" and Tang Baohua's "Development and Performance Research of Strengthened Oil Anti-burning Three-Phase Foam Fire Extinguishing Agent" have studied this type of foam, but most of them require the addition of high amounts of solid particles, with a mass concentration of more than 10%, which makes it difficult to prepare and store foam.

[0003] In addition, in order to increase the spreading speed of the foam, scholars prepared AFFF fire extinguishing agent by adding perfluorooctane sulfonate (PFOS) substances. The hydrophobic and oleophobic PFOS substances can greatly reduce the surface tension and quickly spread on the oil surface to form a liquid film to inhibit the volatilization of oil, thereby improving the fire extinguishing efficiency. However, PFOS substances are a kind of toxic organic pollutants that are difficult to degrade. Currently, many countries have imposed strict restrictions on their production and use. Summary of the invention

[0004] The purpose of the invention is to provide a method for preparing an aerogel foam fire extinguishing agent, which has a simple process and is easy to operate.

[0005] Another object of the present invention is to provide an aerogel foam fire extinguishing agent prepared by the above preparation method, which has strong burning resistance and is green and environmentally friendly.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] In one aspect, the present invention provides an in-situ preparation method of an aerogel foam fire extinguishing agent, comprising the following steps:

[0008] (1) Mix NH3·H2O solution and ethanol in proportion and stir evenly;

[0009] (2) adding template A to the mixed solution of step (1) at 60-75° C., stirring until the solution is clear, and then adding template B and continuing to stir until the solution is clear;

[0010] (3) adding tetraethyl orthosilicate (TEOS) dropwise, stirring and reacting at 60-75° C. for 2 h to form a white slurry;

[0011] (4) adding a certain volume of water to the white slurry obtained in step (3) and stirring evenly, heating to 80° C. and stirring for 0.5 to 2 h; after cooling to room temperature, adding a composite surfactant, stirring and dispersing at a speed of 2200 r / min for 5 min, and performing surface adsorption modification on the aerogel particles;

[0012] (5) Add the dissolved xanthan gum solution and stir for 5 minutes, then add polyethylene glycol, ammonium polyphosphate and urea in sequence, and stir at a speed of 5000 r / min for 30 to 60 minutes; seal the sample and let it stand overnight, and take the upper layer of liquid to obtain the aerogel foam fire extinguishing agent.

[0013] Preferably, the mass concentration of the NH3·H2O solution in step (1) is 20% to 30%; the mass ratio of the NH3·H2O solution to ethanol is 1:1 to 1.5:1.

[0014] Preferably, the template agent A in step (2) is one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and fatty alcohol polyoxyethylene ether sulfate, and the addition amount is 0.005-0.01 mol / L; the template agent B is one or more of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, and dodecyldimethylbenzylammonium chloride, and the molar ratio of template agent A to template agent B is 1:(1-3).

[0015] Preferably, the amount of TEOS added in step (3) accounts for 1 to 3 vol% of the white slurry.

[0016] Preferably, the compound surfactant in step (4) is obtained by compounding anionic surfactant, nonionic surfactant and silicone surfactant in a mass ratio of 1:1:0.2, wherein the anionic surfactant is one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate and fatty alcohol polyoxyethylene ether sulfate, the nonionic surfactant is one of alkyl glucoside and lauryl alcohol polyoxyethylene ether, and the silicone surfactant is 8000, 8022, One of 8002, Dow Corning-0193 silicone surfactant and ionic 6950 silicone surfactant.

[0017] Preferably, the amount of the compounded surfactant added in step (4) accounts for 2.1 to 2.3 wt % of the aerogel foam fire extinguishing agent.

[0018] Preferably, the mass concentration of the xanthan gum solution in step (5) is 0.1-0.3%, and the amount of xanthan gum added accounts for 0.02-0.04wt% of the aerogel foam fire extinguishing agent.

[0019] Preferably, the degree of polymerization of the polyethylene glycol in step (5) is 1500.

[0020] Preferably, the amount of polyethylene glycol, ammonium polyphosphate and urea added in step (5) accounts for 1-2.5wt%, 1-3wt% and 0.6-2wt% of the aerogel foam fire extinguishing agent respectively.

[0021] On the other hand, the present invention also provides an aerogel foam fire extinguishing agent prepared by the above-mentioned in-situ preparation method.

[0022] The invention first adds a template agent into an ammonia-ethanol mixed solution and heats it to dissolve, then adds tetraethyl orthosilicate to hydrolyze and condense it under heating conditions to generate aerogel particles, then adds a composite surfactant to perform surface adsorption modification and steric stabilization, and finally adds a fire extinguishing component to obtain an aerogel foam fire extinguishing agent.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The prepared aerogel foam fire extinguishing agent is prepared in situ by reverse stacking through a template method, and is stabilized by charge repulsion and steric hindrance to obtain a foam fire extinguishing agent dispersed with aerogel particles. The preparation method is simple and there is no need to dry the aerogel particles and then mix and disperse them with the fire extinguishing liquid.

[0025] 2. Aerogel particles dispersed in the foam liquid film can support the foam skeleton and improve the stability of the foam. After the bubbles are broken, the aerogel particles in the foam can be deposited on the surface of the lower foam. The nanoscale porous structure in the aerogel particles can effectively inhibit the occurrence of thermal convection, reduce the thermal radiation of the flame to the remaining foam, and delay the further rupture of the foam, so that a very small amount of addition to the foam can greatly improve the burning resistance of the foam and reduce the cost of fire fighting. At the same time, the aerogel foam fire extinguishing agent is obtained by compounding an organic silicon surfactant and a hydrocarbon surfactant. Under the condition of not containing PFOS and other pollutants, it greatly reduces the surface tension of the fire extinguishing liquid, accelerates the spreading speed of the foam on the oil surface, and improves the efficiency of fire fighting. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a physical diagram of the experimental oil pan in the present invention and the aerogel foam fire extinguishing agent prepared in Experimental Example 1. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Example 1

[0029] 0.625L NH3·H2O solution (25wt.%) and ethanol were mixed in a mass ratio of 1:1 and stirred evenly. 0.0075mol sodium dodecyl sulfate was added to the mixed solution at 68°C and stirred until the solution was clear. Then 0.0075mol hexadecyltrimethylammonium bromide was added and continued to stir until the solution was clear. 25mL TEOS was added and the reaction was continued to stir at this temperature for 2h to form a white slurry.

[0030] Add 3.625L water, heat to 80℃ and stir for 0.5h. After cooling to room temperature, add 110g of composite surfactant (50g sodium dodecylbenzene sulfonate, 50g alkyl glycoside, 10g 8022), and stirred and dispersed at a speed of 2200 r / min for 5 min.

[0031] 0.75L of dissolved xanthan gum solution (0.2wt.%) was added, stirred for 5min, then 50g of polyethylene glycol, 100g of ammonium polyphosphate, and 50g of urea were added in sequence, the speed was adjusted to 5000r / min and stirring was continued for 30min. After the sample was sealed and left to stand overnight, the upper layer of liquid was taken to obtain an aerogel foam fire extinguishing agent.

[0032] Example 2

[0033] 1.25 L NH3·H2O solution (25 wt.%) and ethanol were mixed in a mass ratio of 1:1 and stirred evenly. 0.015 mol sodium dodecyl sulfate was added to the mixed solution at 68°C and stirred until the solution was clear. Then 0.015 mol hexadecyltrimethylammonium bromide was added and stirred until the solution was clear. 50 mL TEOS was added and stirred at this temperature for 2 h to form a white slurry.

[0034] Add 3L of water, heat to 80℃, stir for 0.5h, cool to room temperature, add 110g of composite surfactant (50g sodium dodecylbenzene sulfonate, 50g alkyl glycoside, 10g 8022), and stirred and dispersed at a speed of 2200 r / min for 5 min.

[0035] 0.75L of dissolved xanthan gum solution (0.2wt.%) was added, stirred for 5min, then 50g of polyethylene glycol, 100g of ammonium polyphosphate, and 50g of urea were added in sequence, the speed was adjusted to 5000r / min and stirring was continued for 30min. After the sample was sealed and left to stand overnight, the upper layer of liquid was taken to obtain an aerogel foam fire extinguishing agent.

[0036] Example 3

[0037] 1.875 L NH3·H2O solution (25 wt.%) and ethanol were mixed in a mass ratio of 1:1 and stirred evenly. 0.0225 mol sodium dodecyl sulfate was added to the mixed solution at 68°C and stirred until the solution was clear. Then 0.0225 mol hexadecyltrimethylammonium bromide was added and stirred until the solution was clear. 75 mL TEOS was added and stirred at this temperature for 2 h to form a white slurry.

[0038] Add 2.375L water, heat to 80℃ and stir for 0.5h. After cooling to room temperature, add 110g of composite surfactant (50g sodium dodecylbenzene sulfonate, 50g alkyl glycoside, 10g 8022), and stirred and dispersed at a speed of 2200 r / min for 5 min.

[0039] 0.75L of dissolved xanthan gum solution (0.2wt.%) was added, stirred for 5min, then 50g of polyethylene glycol, 100g of ammonium polyphosphate, and 50g of urea were added in sequence, the speed was adjusted to 5000r / min and stirring was continued for 30min. After the sample was sealed and left to stand overnight, the upper layer of liquid was taken to obtain an aerogel foam fire extinguishing agent.

[0040] Comparative Example 1

[0041] Add 110g of composite surfactant (sodium dodecylbenzene sulfonate, alkyl glucosides, 8022), stirred and dispersed at 2200r / min for 5min. Add 0.75L dissolved xanthan gum solution (0.2wt.%), stir for 5min, then add 50g polyethylene glycol, 100g ammonium polyphosphate, 50g urea in sequence, adjust the speed to 5000r / min and continue stirring for 30min. Seal the sample and let it stand overnight to obtain a foam fire extinguishing agent without aerogel.

[0042] Comparative Example 2

[0043] Add 110g hydrocarbon surfactant (sodium dodecylbenzene sulfonate, alkyl polyglycoside) to 4.25L water, stir and disperse at 2200r / min for 5min. Add 0.75L dissolved xanthan gum solution (0.2wt.%), stir for 5min, then add 50g polyethylene glycol, 100g ammonium polyphosphate, 50g urea in sequence, adjust the speed to 5000r / min and continue stirring for 30min. Seal the sample and let it stand overnight to obtain a foam fire extinguishing agent without aerogel.

[0044] The foam fire extinguishing agents prepared in Examples 1-3 and Comparative Example 1 were subjected to anti-burning tests respectively, using a square steel oil pan with a size of 34*34*5 cm, an anti-burning tank with a diameter of 6.5 cm and a height of 5 cm, and n-heptane as fuel. The specific method is as follows:

[0045] (1) Pour 500 mL of n-heptane into the oil pan, ignite and pre-burn for 50 seconds;

[0046] (2) After the pre-combustion phase is over, release foam into the oil pan to extinguish the fire;

[0047] (3) After all the flames in the oil pan are extinguished, continue to apply foam until it is flush with the edge of the oil pan;

[0048] (4) Fill the anti-burning tank with heptane and place it in the center of the oil pan. After 1 minute, ignite the heptane in the anti-burning tank. The time when the oil pan completely reignites is recorded as the 100% anti-burning time. The experimental results are shown in Table 1.

[0049] Table 1 Burning resistance test results

[0050] 100% burning resistance time / s Example 1 1345±60 Example 2 1194±60 Example 3 1134±60 Comparative Example 1 938±60

[0051] As can be seen from Table 1, compared with Comparative Example 1, the anti-burning time of Examples 1-3 is significantly prolonged, indicating that the addition of aerogel particles can effectively improve the anti-burning time of the foam. This is because the aerogel particles dispersed in the foam liquid film can not only support the foam skeleton and improve the foam stability, but also the aerogel particles can be deposited on the surface of the lower foam after the bubbles are broken. The nanoscale porous structure in the aerogel particles can effectively inhibit the occurrence of thermal convection, so that even a very small amount of its addition in the foam can effectively reduce the flame heat radiation and delay the rupture of the foam, thereby improving the anti-burning property of the foam. Figure 1 It is a physical picture of the experimental oil pan and the aerogel foam fire extinguishing agent prepared in Experimental Example 1.

[0052] The surface tension of Examples 1-3 and Comparative Examples 1-2 was tested using an interfacial rheometer (Tracker) produced by French Teclis Company. The experimental results are shown in Table 2.

[0053] Table 2 Surface tension test results

[0054] Surface tension mN / m Example 1 22.80±0.03 Example 2 23.54±0.03 Example 3 24.42±0.03 Comparative Example 1 21.78±0.03 Comparative Example 2 26.64±0.03

[0055] As can be seen from Table 2, the surface tension of Comparative Example 1 and Examples 1-3, which added an organosilicon surfactant, was significantly lower than that of Comparative Example 2, which used only a hydrocarbon surfactant. Although the surface tension increased with the increase in aerogel content, the addition of the organosilicon surfactant significantly reduced the surface tension of the fire extinguishing liquid, and the reduction in surface tension was conducive to the rapid spreading of the foam on the oil surface, thereby improving the fire extinguishing efficiency of the foam.

[0056] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. An in-situ preparation method of an aerogel foam fire extinguishing agent, characterized in that: The following steps are involved: (1) Mix NH3·H2O solution and ethanol in proportion and stir evenly; (2) adding template A to the mixed solution of step (1) at 60-75°C, stirring until the solution is clear, and then adding template B and continuing to stir until the solution is clear; the template A is one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and fatty alcohol polyoxyethylene ether sulfate, and the addition amount is 0.005-0.01 mol / L; the template B is one or more of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, and dodecyldimethylbenzyl ammonium chloride, and the molar ratio of template A to template B is 1:(1-3); (3) Add ethyl orthosilicate dropwise and stir at 60-75°C for 2 h to form a white slurry; (4) Add a certain volume of water to the white slurry obtained in step (3) and stir evenly, heat to 80°C and heat and stir for 0.5-2h; after cooling to room temperature, add a compound surfactant, stir and disperse at a speed of 2200r / min for 5min, and perform surface adsorption modification on the aerogel particles; the compound surfactant is obtained by compounding anionic surfactant, nonionic surfactant and silicone surfactant in a mass ratio of 1:1:0.2, wherein the anionic surfactant is one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate and fatty alcohol polyoxyethylene ether sulfate, the nonionic surfactant is one of alkyl glucoside and lauryl alcohol polyoxyethylene ether, and the silicone surfactant is one of silok®8000, silok®8022, silok®8002, Dow Corning-0193 silicone surfactant and ionic 6950 silicone surfactant; the amount of the compound surfactant added accounts for 2.1-2.3wt% of the aerogel foam fire extinguishing agent; (5) Add the dissolved xanthan gum solution and stir for 5 minutes. Then add polyethylene glycol, ammonium polyphosphate and urea in sequence and stir at 5000 r / min for 30-60 minutes. Seal the sample and let it stand overnight. Take the upper layer of liquid to obtain the aerogel foam fire extinguishing agent.

2. The in-situ preparation method of an aerogel foam fire extinguishing agent according to claim 1, characterized in that: The mass concentration of the NH3·H2O solution in step (1) is 20% to 30%; the mass ratio of the NH3·H2O solution to ethanol is 1:1 to 1.5:

1.

3. The in-situ preparation method of an aerogel foam fire extinguishing agent according to claim 1, characterized in that: The amount of ethyl orthosilicate added in step (3) is 1-3 vol% of the white slurry.

4. The in-situ preparation method of an aerogel foam fire extinguishing agent according to claim 1, characterized in that: The mass concentration of the xanthan gum solution in step (5) is 0.1-0.3%, and the amount of xanthan gum added accounts for 0.02-0.04wt% of the aerogel foam fire extinguishing agent.

5. The in-situ preparation method of an aerogel foam fire extinguishing agent according to claim 1, characterized in that: The degree of polymerization of the polyethylene glycol in step (5) is 1500.

6. The in-situ preparation method of an aerogel foam fire extinguishing agent according to claim 1, characterized in that: In step (5), the amount of polyethylene glycol, ammonium polyphosphate and urea added is 1-2.5wt%, 1-3wt% and 0.6-2wt% of the aerogel foam fire extinguishing agent, respectively.

7. An aerogel foam fire extinguishing agent prepared by the in-situ preparation method according to any one of claims 1 to 6.

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